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'AD-R122 843 ENGINES/FUELS WORKCSHOP 6-8 DECEMBER 1982 SAN ANTONIO i/iTEXAS(U) SOUTHWEST RESEARCH INST SAN ANTONIO TX ARMYFUELS AND LUBRICANTS RESEARCH LAB D M MANN ET AL. 1982
UNCLASSIFIED AFLRL-164 DAAK70-82-C-0081i F/G 21/4, N
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ENGINES/FUELS WORKSHOP
6-8 December 1982San Antonio, Texas
Sponsored by
U.S. Army Research Office(Research Triangle Park, NC)
DEC 3
and
U.S. Army Mobility Equipment Research andDevelopment Command
(Ft. Belvoir, VA)
Ivor
_ Hosted by
U.S. Army Fuels and Lubricants Research LaboratorySouthwest Research Institute
(San Antonio, TX)
DISChmers
The views, opinions, and/or findings expressed in this document are those of the
authors and not to be construed as official Department of Army positions unless so
designated by other appropriate documentation.
Trade names cited in this document do not constitute official endorsements or
approval of the use of such hardware or software.
Disposition Instructions
Destroy this document when no longer needed. Do not return it to the originator.
ft
1
I
UNCLASSIFIEDSECURITY CLASSIFICATION OF THIS PAGE (When Data Entered)
READ INSTRUCTIONSREPORT DOCUMENTATION PAGE BEFORE COMPLETING FORM
1. REPORT NUMBER 2. GOVT ACCESSION NO. 3. RECIPIENT'S CATALOG NUMBER
AFLRL No. 164 A4. TITLE (and Subtitle) 5. TYPE OF REPORT & PERIOD COVERED
Engines/Fuels Workshop Special, 6-8 December 19826. PERFORMING ORG. REPORT NUMBER
AFLRL No. 1647. AUTHOR(s) S. CONTRACT OR GRANT NUMBER(s)
D. it. Mann, et al. DAAK70-82-C-0001
9. PERFORMING ORGANIZATION NAME AND ADDRESSES 10. PROGRAM ELEMENT, PROJECT. TASKU.S. Army Fuels and Lubricants Research Lab. AREA&WORKUNITNUMBERSSouthwest Research Institute l .BP 0 Drawer 28510, San Antonio, TX 78284
11. CONTROLLING OFFICE NAME ANOADDRESS 12. REPORT DATEU.S. Army Mobility Equipment Research and 6-8 December 1982Development Command, Energy and Water Resources 13 NUMBER OF PAGES292Lab.. Ft. Belvoir, VA 22060
14. MONITORING AGENCY NAME & ADDRESS 15. SECURITY CLASS. (of this report)(i" different from Controlling Office)U.S. Army Research Office, Research Triangle- UnclassifiedPark, NC and U.S. Amy Mobility Equipment Res. is,. DECLASSIFICATION/DOWNGRADINGand Development Cpmmand, Ft. Belvoir, VA SCHEDULE
16. DISTRIBUTION STATEMENT (of this Report)
* Approved for public release: distribution unlimited.
17. DISTRIBUTION STATEMENT (of the abstract entered in Block 20, if different from Report)
18. SUPPLEMENTARY NOTES
19. KEY WORDS (Continue on reverse side if necessary and identify by block number)Diesel Fuel Gas Turbine Engine FuelDiesel Engine Combustion Gas Turbine Engine CombustionDiesel Engines Gas Turbine EnginesAdiabatic Diesel Engine Multifuel Engines continued
20 ABSTRACT (Continue on reverse side if necessary and identify by block number)A basic research workshop was attended by 55 university, government, andindustry personnel on 6-8 December 1982. This conference was sponsoredjointly by the Army Research Office and the Army Mobility Equipment Researchand Development Command. The conference was arranged and hosted by the U.S.Amy Fuels and Lubricants Research Laboratory, Southwest Research Institute.
continued
DD FORM 1473 EDITION OF I NOV 65 IS OBSOLETE1 JAN 73 UNCLASSIFIED
SECURITY CLASSIFICATION OF THIS PAGE (When Data Entered)
UNCLASSIFIED* SECURITY CLASSIFICATION OF THIS PAGE (When Date Entered)
19. continued
Army Mobility Fuels ResearchArmy Ground Vehicle Engines ResearchArmy Aviation Turbine Engine ResearchEngines/Fuels InterfaceAlternative FuelsFuel Properties
20.) continued -
Whe objectives were to identify engines/fuels development technicalresearch barriers. The results of enthusiastic group participation
in the conference deliberations provided substantial guidance forestablishing priorities for Army basic and applied research.
K P,
II
SECURITY CLASSIFICAIO OF THIS PAGE (when Date Enteredi W
Foreword
This document comprises a collection of advance information provided by theindividual workshop authors/presenters. Abstracts and copies of visual aids (asprovided by the authors) are reproduced for use by workshop participants and otherinterested parties. It has been prepared under Contract No. DAAK70o-2-C-0001
-- with Mr. F. W. Schaekel, DRDME-GL, serving as Contracting Officer'sRepresentative. Funds were provided jointly by the U. S. Army Research Office andthe U. S. Army Mobility Equipment Research and Development Command.
To facilitate and stimulate free and open discussion during the workshop, no recordsother than this document will be made. Acknowledgment is given to Dr. D. W.Naegeli for assistance in initial planning of the workshop. Mr. S. 3. Lestz and Dr. W.D. Weatherford, 3r. handled the details of planning the workshop and communicatingwith participants. Ms. Beatrice Moreno provided the physical arrangements.
Special acknowledgment is given to Dr. D. M. Mann, DRXRO-EG, and Mr. M. E.LePera, DRDME-GL, for their participation, encouragement, and suggestions duringthe planning and implementation of the workshop. Publication of this documentwould not have been possible without the cheerful and efficient editorial assistanceof Ms. Rebecca Sears and Mr. 3. W. Pryor.
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AGENDA AND TABLE OF CONTENTSAROIMERADCOM ENGINESIFUELS WORKSHOP
Time Page No.
Monday, 6 December 1982
4:00-6:00 p.m. Registration Menger Hotel6:00-7:00 p.m. Social Hour Menger Hotel
Tuesday, 7 December 1982
7:45 a.m. Bus transportation from Menger Hotel to SwRI8:00 a.m. Registration Southwest Research Institute ----
Opening Remarks
8:30 a.m. Welcome:Lt.Gen. A. W. Betts (ret.),
Senior Vice President, SwRIR. D. Quillian, Jr., ----
Vice President, Energy SystemsResearch Division, SwRI
8:50 a.m. Overview of Workshop: D. M. Mann, ixEngineering Sciences Division,U. S. Army Research Office
Session 1: U.S. Army Programs
9:10 a.m. Chairman: S. 3. Lestz, U. S. Army Fuels & Lubricants 1-1Research Laboratory, SwRI
9:15 a.m. "Army Mobility Fuels Research and Development Program" 1-3M. E. LePera,* Fuels & Lubricants Division, U. S. Army
Mobility Equipment Res. & Dev. Command9:35 a.m. "R&D Strategy for Ground Vehicle Engines" 1-39
P. C. Glance, U. S. Army Tank-Automotive Command9:55 a.m. "Army Aviation Turbine Engine/Combustion Research" 1-53
E. Mularz, U. S. Army Aviation Res. & Dev. Command10:15 a.m. "Army Mobility Engines/Fuels R&D Interface" 1-73
S. 3. Lestz, AFLRL/SwRI10:35 a.m. Coffee Break
*Presented by F. '. Schaekel, USAMERADCOM
V
" • _ . . _ r ' nlI~m R~a¢Rm i~a h~ b m lll) I lla 'V
Time Page No.Session 2: ARO Combustion Research
11:05 a.m. Chairman: D. M. Mann, ARO 2-111:10 a.m. "Transient Catalytic Combustion" 2-3
R. 0. Buckius and R. I. Masel, University of Illinois-Urbana11:30 a.m. "Basic Studies of Catalytic Combustion" 2-5
P. 3. Marteney, United Technologies, Research Center11:50 a.m. "Turbulence-Combustion Interactions in Laminr and Turbulent
Premixed Methane-Air V-Flames" 2-17T. Y. Toong, Massachusetts Institute of Technology
12:10 a.m. "Preignition Oxidation Characteristics of Hydrocarbon Fuels" 2-29R. S. Cohen and N. P. Cernansky, Drexel University
12:30 p.m. Lunch Break
Session 3: ARO Diesel Engine Research
1:40 p.m. Chairman: P. C. Glance, TACOM 3-11:45 p.m. "Diesel Sprays" 3-3
N. Chigier, Carnegie-Mellon University2:05 p.m. "High Pressure Atomization and Thick Sprays" 3-11
F. V. Bracco, Princeton University2:25 p.m. "Wall Effects on Combustion in an Engine" 3-21
F. E. Fendell, TRW Systems2:45 p.m. "Diesel Engine Cylinder Heat Flux andGas Analysis" 3-43
G. L. Borman, University of Wisconsin-Madison3:05 p.m. Coffee Break ----
Session 4: ARO Combustion Research
3:35 p.m. Chairman: E. Mularz, AVRADCOM 4-13:40 p.m. "Ignition and Flame Propagation in Sprays" 4-3
W. A. Sirignano and S. C. Yao, Carnegie-Mellon University4:00 a.m. "Mechanism of Combustion of Hydrocarbon/Alcohol Blends" 4-13
K. Seshadri, University of California-San Diego4:20 p.m. "Acoustic Signature from Flames as a Combustion
Diagnostic Tool" 4-21W. C. Strahle, Georgia Institute of Technology
4:40 p.m. "Combustion and Microexplosions of Water/Oil Emulsions inHigh-Pressure Environments" 4-31C. K. Law, Northwestern University
6:00 p.m. Bus transportation from SwRI to Menger Hotel
vi
vi
Time Page No.Wednesday. 8 December 1982 4
7:45 a.m. Bus transportation from Menger Hotel to SwRI --
Session 5: Fuels/Engines Tedmology
8:15 a.m. Chairman: F. W. Schaekel, MERADCOM 5-18:20 a.m. "tARO Basic Study of Fuel Storage Stability" 5-3
F. R. Mayo and B. Y. Lan. SRI-International8:40 a.m. "AFLRL Basic Research on Fuel Storage Stability" 5-7
G. H. Lee and L. L. Stavinoha, AFLRL/SwRI9:00 a.m. "AFLRL Fire-Resistant Diesel Fuel Mechanisms
Basic Research" 5-13W. D. Weatherford, 3r. and D. W. Naegeli, AFLRL/SwRI
9:20 a.m. "Synopses of Other Related Basic Research at AFLRL/SwRI" 5-25T. W. R III, 3ohn 0 Storment,Ed C. Owens, and Lee G. Dodge, SwRI
10:00 a.m. Coffee Break
Session 6: Discussion Groups
10:30 a.m. Relocate to Designated Conference Rooms 6-110:35 a.m. Reciprocating Engines/Fuels Discussions
Discussion Leader:S. S. Lestz, Penn State University
10:35 a.m. Turbine Engines/Fuels DiscussionsDiscussion Leader:
A. M. Mellor, Drexel University12 20 p.m. Lunch Break -.-
1:-30 p.m. Continuation of Discussion Groups2:30 p.m. Break2:50 p.m. Reports by Discussion Leaders3:10 p.m. Recapitulation ,--
D. M. Mann, ARO3:30 p.m. Transportation from SwRI to Airport or Menger Hotel --
vii
Lpro
wmiNTODcTIoNOVERVEW OF WORKSHOP
David M. MannEngineering Sciences DivisionU. S. Army Research OfficeResearch Triangle Park, NC
This Engine/Fuels Workshop comes at a critical time. The Army is inthe process of developing strategy for employment of its forces in the nextN century. Central to this strategy is rapid movement and high mobility ofair and land components. Coupled with the projected fuel requirements ofArmy systems, increased mobility will bring staggering fuel logistics problems.These difficulties are being compounded by the predictable decline in fuel"iquality" as non-conventional fuels came into use. Basic research can pro-vide the directions for the new technologies needed to meet the Army's futuremobility requirements.
The purpose of the title "Engine/Fuels Workshop" was to call attention tothe fact that we are dealing with a coupled problem. Current, "well engineered"combustion systems deliver high combustion efficiency when operating at theirdesign point on their design fuel. Most suffer serious degradation in otheroperating regimes or with other fuels. The challenge is to develop the under-standing of the interactive fuel and combustion processes which will allow thebroadest range of operation and fuel utilization. Additionally, the availa-bility of reliable models of the combustion process will allow less hardwareand test-intensive engine development and provide initial designs closer tooptimum. Of course, the fundamental goal is not juA. combustion efficiencybut rather energy efficiency, the conversion of fuel -stored energy intouseful mechanical energy. In this respect, compound engines, for examplethe turbo-compound adiabatic diesel, provide promise for real efficiencygains but also provide challenges for combustion optimization.
At this workshop, researchers have been asked to describe their currentwork and to give their perspectives on the pressing issues in this area. Thediscussion sessions which follow these presentations will allow us to focuson the major issues and define critical research needs. Participants areencouraged to present both evolutionary and revolutionary thoughts as bothare needed to meet the challenge.
ix
1-1
Session IU. S. ARMY PROGRAMS
Chairman: S. 3. LestzU. S. Army Fuels and Lubricants Research Laboratory
Southwest Research InstituteSan Antonio, TX
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U.S. ARMY MOBILITY FUELS
P R&D PROGRAM
BYM. E. LEPERA
U.S. ARMY MOBILITY EQUIPMENT R&D COMMANDFUELS AND LUBRICANTS DIVISION
ENERGY AND WATER RESOURCES LABORATORY
PRESENTED AT THE ARO/MERADCOMENGINE/FUELS WORKSHOP
7-8 DECEMBER 1982
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ARMY MOBILITY FUELS PROGRAMMAJOR THRUSTS
6.1 BASIC RESEARCH
* 0 FIRE-RESISTANT FUEL MECHANISMS (OPTIMIZATIONPURPOSES)
* HETEROATOM /COMPOSITION EFFECTS ON DEPOSITS/WEAR
* 0 FUEL DETERIORATION ADDITIVE INHIBITIONMECHANISMS
6.2/6.3A DEVELOPMENT
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0 FIELD-EMERGENCY FUELS CAPABILITY
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1-39
Engine Research,Development, and
Acquisition Strategy for U.S.Army Ground Vehicles*
Paul C. Glanceand Richard Munt
U.S. Army Tank-Automotive CommandWarren, MI
Ir
THE US ARMY CONDUCTS RESEARCH, promising at any given time. Consequently,Development & Acquisition programs on a there is need for a management strategy bywide variety of tactical and combat vehicles which the US Army Tank-Automotivetypes. The spectrum of possible engines for Command (TACOM) can more effectivelyuse In these vehicles is very broad (Figure 1). direct Its R&D resources to those programsAvailable resources for the research and which will provide the greatest benefit to thedevelopment (R&D) of candidate engines, overall effectiveness of the Department ofhowever, are far more limited and, further, Defense (DOD).
* not all of the possibilities are equally Faced with this challenge, TACOM has
ABSTRACT
The US Army conducts Research, engines wherein there are no cost-effectiveDevelopment & Acquisition programs on a commercially available engine options. Thewide variety of tactical and combat vehicle second part of the strategy is the developmenttypes. Available resources for the research of an objective, quantifiable methodologyand development (R&D) of candidate engines, which Integrates the highest priority goals intohowever, are far more limited. Consequently, an overall evaluation of the cost/combat (orthere Is need for a management strategy by operational) effectiveness of candidatewhich the US Army Tank-Automotive engines.Command (TACOM) can more effectively The methodology exploits the historicdirect the limited Department of Defense ma.4r goals of the R&D program which are(DOD) R&D resources to those programs which reviewed in detail. This methodology will bewill provide the greatest benefit to the overall further developed and considered as aneffectiveness of the DOD. evaluation screening tool to determine
objectively the most promising engineIn response to this need, TACOM has alternatives warranting further development,
evolved an engine R&D two-fold strategy. test and evaluation as well as to determine theThe first part of the strater is the limitation reL lve significance of the various R&D goals ,of TACOM's R&D efforts to that range of and their specific targets.*Manuscrlpt submltted to AE for publication.
1-40 ENGINE CANDIDATES
CEHET CNE N S
E BlowI ENORIE OTOCRE DES REANINE SIRNSYTMSETTO ENGINE S NGIYE
T 79XLEUNNT HRBSNEENIS E
FIg. 1N- ERlIne Candidtes
evolved a two-fold engine R&D strategy. This R&D goal because it is only through thepaper traces the evolution of this strategy attainment .of these goals that a candidte
*with first a discussion of the Army's highest engine can show up well in the evaluation.priority pround engine R&D goals. These goals This paper shall, therefore, explain first,hav, been quantified by a series of parametric .the critical engine R&D goals and then thetrend charts, an understanding of which leads two-fold engine Research, Development, and
*to an appreciation of the first part of the Acquisition strategy which followsCstrategy, the limitation of TACOMCs R&D
efforts to that range of engines wherein there PROPULSION SYSTEM GOALS
are no coat effective commercially availableengine option.. The paper then introduces the Figure 2 summarizes TACOM's highestseond part of the strategy, namely the priority Propulsion System goals. The Army isdevelopment of an objective, quantifiable interested in developing and procuring conmtmethodology which integrates the highest effective engines which provide gocd overall
. ..0 Ioity goals into an overall evaluation of the "mission fuel economy, wide fuel tolerance and,cost/combat (or operational) effectiveness of in combat vehicles, high power density andanmdidte engines. This approach to engine rapid acceleration. Additionally, the enginesseletion potentially can provide the Army must be reliable, durable and maintainablewith a simple, quick evaluation leading to the with the minimum resources, (money andelimination of the less desireable alternatives, manpower). All this must be achievable at theThe methodlogy is applicable to the best possible overall cost. These goals, of
*evalti~on of both commeriaflly-avalable and course, are often competing and the finalto Ar'my-developed engines. Of importance, engine design will be determined by the -
• thomugh, is the fact that this methodology relative weighting assigned to each goal,determines the relative importance of each TACOM has conducted parametric
IGIININIIN CCE
PROPULSION SYSTEM GOALS ENGINE 20 suFIC cost 1-41
g. LOW UFE CCLECOST --
p91.EUINSIY- SMALL COMPACT PROPULSION SYSTEM
ERFORMANCE* HIGH PERFORMANCE. EFFICIENT, WIDE FUEL I I ITOLERANCE -i
EAy:D -RELIABLE. AVAILABLE. MAINTAINABLE. DURABLE -ill i i -Fig. 2- Propulsion System Goals
studies which quantify the values of thes Fig. 3 - Engine 20 Yea Life Cycle Cost-goals for various engine classes. The results .of these parametric studies of the cost, powerdensity, performance and RAM-D goals are i'II I ," Odicse pe* NE ROCU'REMENT COST 11VEL
The DOD defines "Life Cycle Cost : - - i a t(LCC)" to-be the summation of the costrequire develop and test (R&D cost), I'I-L
procure (acquisition cost), and operate andsupport (O&S) for the life of the system --(including overhaul cost, if any). The life of l cvicmost weapon systems is 20 years and I,.--,. I _.O ._atherefore, the cost of operating and supportingI - wa3the system for 20 years is usually the largest --
element of life cycle ast. IThe LCC of vario i engines which the 0 MIT
SUS Army has in operation is shown in Figure 3. N - -
The first five engines shown, which cost .. uI 6/50I 11111approximately $250 per horsepower for 20 r i--- I I
ye s of life, are com m ercial engines. T he g ;6 7 6 0 ISIII*,o . 161
last two engines are the Main Battle Tank - _ - --- ",(special military) engines which have LCC Fig. 4 - Engine Procurement Cost Levelslevels of approximately $500 per horsepower
. for 20 yars of life. These LCC date. are notdiretUy comparable between vehicles since These procurement cost data are not directlythe use and mileage of each vehicle cass comparable between engines since the
4 varies. Note that the R&D costs typically are production rate, time frame, and accessoriesa small element (less than four percent) of the 0"T aiw for each engine procurement.total LCC. Nonetheless, these types of parametric cost
Each cost element of LCC can be Jata can be used to estimate the cost ofanalyzed to determine parametric engine design candidates which have not yetrelationships for the various clames of entered production and are often useful inengines; for example, Figure 4 . of preliminary evaluations.engine procurement costs and2eWSome A significant conclusion drawn fromparametric cst trends for five classes of Figures 3 and 4 has prompted the formulationengines and five procurement cost levels, of the first aspect of the TACOM R&Dcommercial passenger car high production rate strategy. It is apparent that commercialgaioine engine ($7/HP), commercial truck engines are less expensive than military-medium production rate diesel engines designed ones. There are a variety of reasons
O($0/HP), military (tank) Jiesel engines for this: lower procurement cost, lower R&D($60/HP), military (tank) regenerative gas est, but principally lower O&S cost. Thetulbie engines ($90/HP), and military lower O&S cost of the commercial engineshetlicoter gas turbine engines ($100/HP). arises largely from the lower maintenance
I -42costs, as fuel costs per horsepower are roughly horsepower. Figure 5 presents the engineequal. It follows then, that it is more cost specific weight as a function of design power.effective for the Army to procure commercial Each engine class (turbine or diesel) is seen toengines whenever possible (with military form a separate curve. The lowest lineadaptation, as necessary). Only when there represents the simple cycle turbines andare no suitable commercial options (as occurs demonstrates the very low specific weight ofIn the very large engines), should a purely that type of engine. Of course, this is themilitary engine be considered. reason that simple cycle turbines are selected
in aircraft and helicopter applications. ThePOWERDENSITY recuperated and regenerated gas turbine
engines have considerably higher specificPower density is a measure of the ability weights. The weight penalty here is
to package the engine or power unit in a small associated with the heat exchanger and thevolume with minimal weight. This feature is rquI ctlng. There is a distinct break inparticularly important to combat vehicles the at the low-power end representingwherein excessive volume committed to the regime of the automotive gas turbine. Thepropulsion greatly exacerlibates the vehicle reason is two-fold; first, the heat exchangerweight problem through the extra armor is, thus far, a rotating regenerator whichprotection required to house the unit. Vehicle provides greater effectiveness with a smallerweight, in turn, is a significant consideration volume and weight (but is limited to lowerbecause of Its adverse effect upon pressures); and, second, the volumetric andperformance (fuel economy and acceleration), weight constraints are imposed more severlycost, and air transportability, upon automotive applications than on trucks.
Power density is described quantitatively Diesel engines, except for the adiabaticin terms of specific weight and specific diesel, tend to have higher specific weightvolume, that is, the weight or volume per values than the turbines. The diesels fall into
ENGINE SPECIFIC WEIGHT VS GROSS HORSEPOWER
*LOT S
D333C -N '"C250
tENOT 6733.530 41
UITSU 19
320
=6e VSJl /T~
04-531 E0 79v03 AVS19
A.,
VW
I G I A IAWN 1 3 0
0 2 4 6 8 10 12 14 16
GROSS HORSEPOWER GHP x 1000 Fig. 5 - Engine Specific Weight
ADIABATIWAINEL AW CHGSIMPLETUIMN
T-700
1-43four separate classes. The first includes air combat vehicle occupies approximately 40% ofcooled diesels of exclusive military design and the under-armor hull volume. Of that, only ause. The second is the range of truck, portion is taken up by tha bare engine; the restconstruction equipment, and militarized fs occupied by ancillary equipment such ascommercial diesels that span the low-to-high radiators, air cleaners, induction and exhaustoutput diesel range. The third is the adiabatic ducting, transmission, and fuel Fuel isdiesel that shows well here because of its considered here in the volumetric study asIghly efficient extraction of input energy at there may well exist a Lade-off betweenlittle penalty in weight or volume (the engine size and elficiency on one hand andturbocompounding device). The fourth, and mission fuel required on the other. Forlast, Is the automotive-sized diesel In the example, the AGT-1500 gas turbine engineautomotive-sized diesels (less than 200 HP), used in the M1 Abrams Tank has a recuperatorthere is a break in the trend represented by w~ich imposes a volumetric penalty of about 5the band of conventional low-to-high output ft , but in doing so providas a 40% reductiondiesels. This again represents the special In the average mission fuel eee e y. .. ,constraints imposed by automotive design on Figure 7 suramarizes the volumethe weight and volume, even at the possible breakdown of the propulsion package in a tank.expense of the extraordinary durability Note that if the engine sLze alone is reducedattributed to the truck dieseL by one-half, the total propulsion system
Figure 6 presents the specific volume, volume is reduced by only 1'/ %. If however,which Is the second measure of power density. an adiabatic en:vine were successfullyThe trends and arrangements here are similar developed for combat vehicles, not only wouldto those in Figure 5 and one may draw the the engine size be ceduced by 50%, the coolingsame conclusions. Comparisons such as these system would be reduced by 66%, and the fuelhowever, do not provide a complete picture. system by 40%, for a total system propulsionThe propulsion system in a typical fielded systems volume reduction of 39%. Dramatic
ENGINE SPECIFIC VOLUME VS. GROSS HORSEPOWER0 LOT 45
KNOT 67O NNC 250
06-4-71o
037200
WI LOS 46503-53
* NI~RC 4000 W)
4 ~L 818 * Vf
:,,
11W01
312 4 6 10 12 14 16GROSS HORSEPOWER GHP x 100
Fig. 6- Eaiglne Specific Volume
AUTO . .
01
1-44 PROPULSION SYSTEM SIZE ENGINE SPECIFIC VOLUME
TYPICAL FIELDED VEHICLES POWER
PROPULSION SYSTEM -40% Of ARMOR VOLUME
EN"M
-. 0- WN tayT.. _. --- e- -ma..
Fig. 7 Propulsion system Size, Typical "-, J ii .-... WINIOUIEOS OP NOISPOWER
Fielded Vehicles Fig. 8 - Engine System Specific Volume
reductions In the size of advanced rotary and better than the regenerative gas turbine orgas turbine powerplant installations also are air-cooled diesel systems. At lower powerspossible. Nonetheless, the major reduction of (below about 900 HP), the rotary systemsome sizeable ancillary equipment and fuel volume becomes superior even to that of theneds In the adiabatic diesel give that engine a liquid-cooled diesels, a fact attributable to itsmajor boost toward meeting TACOM's power flat slope on the curve implying a uniformdensity goal. By comparison, the gas turbine sealing with size. As a system, the adiabaticengine's inherently good power density is diesel looks much better than it did as a baresomewhat offset by twe factors. First, the engine alone because of the absence of arecuperated gas turbine engine today does not cooling - system and the reduced fuelpoess a fuel economy (a performance requirement.parameter) equal to that of a good diesel, and Due to the impact of power density on sohence, greater fuel capacity is required for a many features of importance to militarygiven range. Second, the gas turbine today vehicles (performance, cost, andprovides less work per pound of air, and hence, transportability), this goal assumes majorrequires higher air flow, which leads to proportions in the development of futuregreater air induction, filtration, and exhaust engines as well as in the selection of existingvolumes than are required by the diesel engines for near-term systems. For future
One approach to exploring the power engines, Figure 8 projects some expectationsdensity of the propulsion system as a whole is of what might be attained. To achieve thispresented in Figure 8. This portrays the power density, close integration of thespecific volumes not of bare engines, but of engine/transmission system will be required.engine systems. Many of the data points areestimates based upon empirical rules PERFORMANCEformulated from previous experience.Included in the volume count are engine, There are three performance parametersengine cooling, if any, induction/exhaust, air that TACOM considers as prime: Vehiclefiltration, and fuel for a 275 mile cross- acceleration, fuel economy, and multifuelcountry cruise. Auxiliary Power Unit (APU) capability. Acceleration, useful to combatfunction,- if separate, and transmission vehicles for survivability, can be , lewed involumes are not included. A comparison terms of the vehicular horsepower t-weightbetween Figures 6 and 8 reinforces the ratio. Figure 9 shows this ratio for a varietyvalidity of treating the specific volume of the of vehicles. Note that current tanks, such asentire system, rather than that of the bare the M60 and the Russian T-64, are at 14engine. First, the present regenerative gas horsepower per ton power level. The newturbine system at high power is seen to be only combat vehicles, Ml and M2, have largercomparable in volume to that of the military, powerplants which produce approximately 25air-cooled diesels (e.g., AVCR-1360 vs AGT horsepower per ton. For reference, passenger1506) and largerthan could be expected from car power level is approximately 75liquid-cooled diesels extrapolated to these horsepower per ton. The relationship betweenpower levels. Second, the Wankel or rotary power-to-weight ratio, acceleration, andengine system at a high power level is no survivability is seen in Figure 10. This
1-45ENGINE HORSEPOWER VS VEHICLE GROSS WEIGHT.
PASSENGER CAR HORSEPOWER TREND I T72.0375 HP/LB = 75HP/TON BASE I
1. NORM ASP. DIESEL 002. STRAT. CHG. OTTO -RECIP.
1U 9011 3. STRAP CHG. OTTO. ROTARY I O IW 4. UC. OTTO. ROTARY
S. TURBO CHGD DIESELUA7. STIRLING 000000 .+,/,m s.U., otto RECl,
8. INGLE SHAFT TURBINE - BRAYTON _ ___
. FREE SHAFT TURBINE RATON113
wz ,,- -,,,K00 ma'n I
1 2 4 B LB LB U M 40T M0 TOS
I IS- GROSS VEHICLE WEIGHTFIg. 9 - Engine Horsepower vs Vehicle Gross
Weight
SURVIVABILITY VS. DASH DISTANCE example utilizes the Army's mobility andLO threat models to compute the probability of
survival as a function Qf exposur'e dstance to* a typical weapon for ae22-ton tracked vehicle
U- CURRENT UMP ThREAT AT THR~EAT RANGE with, first, a 500 HP engine and, second, vl(650 HP engine. The shorter exposure time
• over a given distance by the more rapidly
91 .
= u accelerating, hiher powered vehicles llows65 H less reaction, tracking, and reloading time by
i • tie threat weapon.o.4,A Fuel economy is important to both
tactical and combat vehicles becase of its
_Y ........... impact on LCC and logistics. In adldition, for' combat veildes, fuel must be placed largely,
or better yet, exelusively under armor
*: protection. Thus, the more fuel needed for a, • • ' v' v• i given range requirement, the heavier and more
* O 0 300 400 NO 600 costly the tank.DISTANCE (METERS) Fuel economy in an engine is, of coarse,
usually measured by the brake-specific fuelFf. 10 - Survivability vs Dash Distance consumption (BSFC). Figure 11 presents the
1-451-45 BSFC OF ENGINES. m20
.1
U3226 HRS 0 . 4153 GALto00 TOTAL In lo0 TOTAL
so+. b 30, 40 0, o o o. , 100-I40 "T C PERCENT POWER PERCENT POWER
.gO" 'l" ,!,, T.C. DlSELl
I -.. o(ReCY, MI ANNUAL PEACETIME USAGE
,.T. Aav Om fIn Fig. 12 - MI Annual Peacetime Usage
.30.30 S&Sum" (Rem
AMhAIc at each power point of the cycle. Thus, theidle and low power engine fuel economy is
o- very important in combat vehicle applications.The improvement in low power fuel
economy is achieved by the use of a free.- -power turbine, variable geometry to maintain
a high Turbine Inlet Temperature (TIT) at lowpower and adequate regeneration. For the
kI wo a6 ilo 2,500 F. lIT just suggested, a recuperatoroorPERCENT POWER regenerator capable of operation at 2,000 F.
Fig. 11 - BSFC of Engines at idle may be needed. This Introduces theneed for ceramic materials, such as Siliconcarbide or Silicon nitride. Considering the
typical 6SFC curves as a function of percent possible pressure ratios (15:1) that may bepower for a variety of engine types. These involved to achieve acceptably low airflows,data are from Reference (1) and army the use of ceramics in a recuperator becomessources. Note that the simple cycle gas a major technical challenge. Several otherturbine that stood out so well in Figure 6 mechanisms, both thermodynamic andbecause of its excellent power density, now mechanical, have also been proposed tostands out for its very high fuel consumption: improve low power fuel economy for gasSpace gained in small engine volume will be turbines, but will not be discussed in thistaken by fuel Consequently, this type of paper.engine is not suitable for ground vehicles. In The third aspect of the research andthe middle range are a variety of diesels, development performance goal is thegasoline reciprocating, rotary, regenerated achievement of multifuel capability. Thefree-turbine and single-shaft gas turbines. national defense depends on a guaranteedThe bottom line shows the demonstrated fuel energy supply, in particular, a guaranteedconsumption for the adiabatic diesel engine, supply of liquid hydrocarbon fuels.This engine is the most fuel efficient ground Alternatives are needed that are domesticallyvehicular engine in the world. It represents a controllable; consequently engines must besevere challenge to the gas turbine. To be developed to operate on those alternate fuels.competitive, the gas turbine will have to The DOD is committed to a long-rangeoperate at a hjgh turbine inlet temperature, program to achieve an orderly transition toperhaps 2,500 F, and be highly recuperated synthetic hydrocarbon fuels in the 1985 toand poesiblM intercooled. While this will 2010 tlmeframe. In support of this policy, theprovide high efficiency at high power, there Army has initiated an alternative fuels R&Dstill remains the problem of low efficiency at program that is expected to yield commericallow and idle power for as Figure 11 shows, engine modification kits, thereby allowing thethere s a dramatic increase in the BSFC of all US Army ground tactical vehicle fleet theengines at sufficiently low power. In aircraft flexibility of operating on a wide range ofand line-haul trucks, this is less a concern as conventional and synethic fuels.their duty cycles are predominatly at higher The ideal multifuel engine is defined forpower. FigL 12 shows the peacetime annual Army purposes as: "An engine with the abilityduty cycle foV Army Combat vehicles. Other to operate on a wide range of alternaterelevant cycles are the 24 and 48 hour hydrocarbon fuels (from gasoline to diesel,battlefield cycles. Shown also in Figure 12 Is including shale oil or coal derived fuels, with athe fuel consumed by the AOT-1500/M1 tank wide spread of octane and cetane tolerance) in
-1-47
mdlitary vehicles without requiring physic FUEL cE-rNE a vImosfrv RAME
.,djustment in the field or eompromisn.engine performance or life." An emergency _"__
ruel, as opposed to the alternate fuelsdescribed previously, is one with which anengine can be made to operate wel enough for 4.
the basic purpose to which it was designed, butwith which the engine can be expected to ,E IT. wq isuffer some degradation in performance and , . M.A.
life. 4N I fwFigure 13 displays the distribution of .... . ,.--
fuels of interest according to cetane number . "iI . im i S ll m uI -
and viscosity which largely govern the fuel , .nerformanee in internal combustion engines. .'here are other fuels properties, such as U 4 , ,* .
lubricity, which also must be considered. ,e I
viscosity, but not the cetane number, affects -W -,Zthe combustion of gas turbine engines. The Fig. 13 - Fuel Cetane and Viscosity Rangeimportant points to understand here are, firstof all, that the DOD multifuel definitionencompasses a very large range of conditions,,nd second, that 100% alcohols are not within ENGINES VS. ALTERNATIVE FUEL SUITABILITYthat range, although alcohol blends may be.
Figure 14 summarizes the multifueliotential of various engine types. Two typesof engines have inherently poor multifuel S.-k saprnon S,,ratd Sidt!apabiities: Gasoline spark ignition engines _ __ m Ch" am
.ecause of their octane sensitivity and dieselopen-chamber compression ignition engines aM o 000 0 000 000because of their relative cetane sensitivity. am ON 000 000 000For those reasons, conventional ope-chambered engines will be phased-ut of the . .0 000 000-Army inventory and replaced by wide fuel 0M 00 0 00 0
tolerant engines in the 1985-2000 tlmeframeGas turbines. and Stirling engines are Ai" 00 0 00 000potentially good multifuel engines becausethey are continuous combustion engines. Hmf 0 0 0
The three performance considerations OOTvc..icdT- ma phdiscussed here do not exhaust those of interest 0 0 v,,.*,to the Army. Two others are worth -
Aighlighting. The first is cold-start capebility. Fig 14 - Alternate Fuel Suitability of Engines.he Army requirement is for start-up within
one minute using only the vehle batteries.'ith DF-2 fuel at an ambient 20 F., and DF-1 ENGINE TORQUE CHARACTERISTICSat an ambient -25 F. I
The second is the torque characteristic i -
and output RPM of the engine. The4,ignificance here, for existing systems, is the mvailability of a suitable off-the-shelf *
transmission. For new systems, the.ignificance is the ability to tailor -thetransmission for minimum size. In this latter4ituation, the benefit accrued is measured interms of the power density, if that term isdefined to include the transmission (as it wasnot in Figure 8). Figure 15 shows torque vgutput speed examples of three engines, a
liesel, a rotary, and a free power turbine gasturbine. The gas turbine, in this case, couldimpaet both size and efficiency of thetramlsion by elimination of the torqueconverter that is required for the other n 40 Wengines shown. Furthermore, the typically %0~n11igh output speed of the power turbine might Fig. 15 - Engine Torque Characteristics
1-48
also be used to advantage by providing the MEAN TIME BETWEEN (CRITICAL) FAILURESgear changing at high speed and thus, lowtorque. This also could materially reduce the _ - 'transmission size, although with, perhaps, a WIA A
minor compromise in efficiency. Torque and
total power together do not completelyaddress the acceleration requirement, ofcourse. Engine response time to power 4ftdemand must also be addressed and, indeed, • "-
can be of considerable impact on gas turbineand highly turboeharged diesel performance. 3.-
In summary, then, the principal z • ', •tperformance requirements for the Army areacceleration for combat vehicles, fuel --
economy, and multifuel capability. Thesecharacteristics impact survivability, LCC, and 1--,00availability. Ancillary considerations of cold tstart torque impact availability and power -
density, both of which affect the combat 0 ,_effectiveness. ,. w 7 ices .,.. ,,
GROSS HORSEPOWERFig. 16 - Mean Time Between Critical Failures
RAM-DTACOM RESEARCH, DEVELOPMENT, AND
RAM-D is the acronym for reliability, ACQUISITION (R,D&A) STRATEGYavailability, maintainability, and durability.The impact of these collective considerations As a consequence of the previouslyhas a heavy influence on the utility of an discussed goals and parametric trend studies, aengine to the Army. Excessive maintenance, strategy has evolved for the management ofeither scheduled or unscheduled, impacts the engine R,D&A efforts, which involves twonumber of vehicles available for duty at any parts. The first is the concentration of R&Dgiven time. Additionally, reliability impacts efforts to that range of engines wherein nothe conduct of a battle by further reducing the satisfactory commercially available enginenumber of vehicles succeeding in the exists. The second is the development of anexecution of the required missions. RAM-D objective, quantifiable methodology whichalso impacts the LCC significantly as one of integrates the highest priority goals into anthe major components (with fuel) of the overall evaluation of the cost/combat (oroperations and support costs. Thus, operational) effectiveness of candidateimprovements in this area have a marked engines.impact on both sides of the cost-effectivenessequation. RANGES OF ENGINES
Figure 16 shows the historical Army datafor the mean time between critical failures Motivated by its limited resources and a(MTBCF) for typical engines. Note that the requirement to provide engines for a largebest commercial and military diesels achieve variety of tactical and combat vehicle types,600 hours between critical failures. The TACOM has developed a management strategyRAM-D experience of gas turbines in the to concentrate the limited DOD resources toaircraft field has been remarkable. the highest priorities. There are three sizeNonetheless, the ground vehicular application regimes: Below 500 HP, 500 to 1,000 HP, andIs somewhat different and the RAM-D cannot over 1,000 HP. Each of these regimes isbe expected to be entirely similar. The characterized by a particular relationship toArmy's experience with the AGT-1500 gas the availability of commercial alternativesturbine engine in the M1 tank has been too which can be exploited.short, as yet, to provide mature RAM-D data Below 500 HP, because of the lowerthat do not reflect the learning trials of both procurement cost, ready availability andthe user and the manufacturer. proven cost effectiveness of commercial
The Army goal for future combat engines, the Army will use commercial-baseengines is 1,000-hours MTBCF and 2,000-hours engines, in some cases, however, the Armylife. Achievement of this goal will have a must develop modification kits to meet specialmarked impact on the LCC and on the combat DOD goals, such as wide fuel/synthetic fuelor operational effectiveness of the vehicle capability while maintaining high efficiency.trough improved availability and reliability in By combining stratified-charge and adiabaticthe fild, technology into commercial engines, it
1-49appears that these goals can be achieved. ENGINE R&D STRATEGY
Because of the desire to exploit commercialengines, the engine options are generally Soo HP
limited to diesels in this power range. In the500 to 1,000 HP range, the Army can use 0 USE COMMERCIAL BASE ENGINES AND TOOUNGeither a highly modified commercial engine or. DEVELOP MODIFICATION KITS FOR
- WIDE FUEL/SYNTHETIC FUEL CAPABILITY
a military-designed engine, depending upon the - NIGH EFFICIENCYavailability of a suitable commercial engine tomodify. Modifications may be extensive or IcRGED/, ADIABATIC,
minor, but in the case of a diesel engine, CHEGD
higher power is often achieved through 500- 1000 HP
Increased turbocharging and, in future cases, 0USE. HIGHLY MODIFIED COMMERCIAL ENGINE
converting the engine to some degree of ORadiabaticity. . MILITARY DESIGN ENGINE
Increasing the level of turbocharging I- ' Imay require, in addition to reduction of the i o,-compression ratio, redesign of the load-carrying parts such as the pistons, rods and > 1000 HP
bearings to accommodate the higher load. DEVELOP MILITARY DESIGN ENGINEAgain, in this size range, only a fewcommerially designed gas turbine truck I ' ' ' I[o..engines are currently available. Gas turbine
engine higher power can bo achieved, within Fig. 17 - Engine R&D Strategystructural and aerodynamic limits, byincreasing the compressor/turbine speeds andthe TIT. Beyond that, resizing of the air pathis ncessary, nd finally, increased cooling or GAS TURBINE DEVELOPMENT STRATEGYdifferent materials to accommodate a much T ", nu €I.Increased TIT. These are major revisions to ga M .the engine. 4 £10,. I1 $10-HO
In the over-l,000 HP range, commercial , Z.-
engines for vehicle application are nonexistant -W
and the Army must develop unique militaryengines. The appplication here is tracked
combat vehicles, and in particular, the Main 7a11nm9um [WWI A"?
Battle Tank. In the past, gasolinereciprocating engines have been used, to be
-: replaced later by diesels. Most recently, a mm 11110 " a4C,,.
recuperated gas turbine, the AGT-1500, has IIIt IA
been employed. For the next generation MainBattle Tank, gas turbine, adiabatic, and rotary afm K,.I #IITI Im.engines are all strong candidates. Figure 17 mMUIuIN rsummarizes the above discussion andgraphically displays the three power ranges Fig. 16- Ga Turbine Development Strategy
inherently in the first aspect of TACOM's£.D&A engine strategy.
Consistent with this "power range"stratgy, Pigure 18 shows how gas turbine ADIABATIC DEVELOPMENT STRATEGY
Sngines may be applied to a range of military TYPCALvehicls. Commereial gas turbines such u the CM NM WoRAOM APPA INo (To%GT-401 and GT-404 turbines could be adapted ..for military application with slight . ai Adifi.Uon, in the 300 to 600 HP rangewhieh would have application to the vehicles Aihown on the right. These commmerical gas .UjIL9 9.turbines could be up-rated to 700-1,000 HP Ku
and applied to a range of military vehiclesshown on the right. In the 1,500-2,000 HP - ,. - LffrlL-rage, an entirely new gas turbine would have KO' Mto be developed for the future Main Battle "Tank. A- AWMsAICm- -
Figure 19 shows how adiabatic diesel -
4 elno may be applied to a range of military -1 vehicles. Starting with a commercial 250 HP F 19 - Adiabatic Development Strategy
eP
: .I . -. - . . . . . , . " - . • -. '. . . . . ' . ,
1-50engine, which is in the 5-ton truck, an shown that its performance and dependabilityunooled, turboeharged version of this engine are such that its selection results in a higherincorporating some ceramics could be applied number of combat vehicles successfullyto 5- and 10-ton trucks. By adding a completing the prescribed mission. Thus, theturbocompound system and more insulation, it approach to evaluating the cost/combatis technicaUy feasible to build a 500-700 effectiveness of two or more engineadiabatic engine, again based on a commercial candidates is to fix the total budget allocatedengine block. In the Main Battle Tank to the vehicle fleet (for each enginecategory, the adiabatic diesel engine must candidate) and then compare the missionbegin with an all new design to be competitive success of the candidates. This is done bywith the good power density of gas turbine and first determining the number of vehicles, withrotary engines, each type of engine, that can be purchased,
operated and maintained for a fixed totalCOST/OPERATIONAL EFFECTIVENESS dollar Investment (this descends directly fromMETHODOLOGY LCC analysis), then calculating and comparing
the number of combat vehicles that willThe second part of TACOM's engine survive with these engines, giving
R,D&A is the employment of a standardized consideration to the propulsion systemcost/operational effectiveness methodology performance, availability, and reliability. Thiswhich integrates the previously discussed goals concept of effectiveness and a methodologyinto an objective quantification of the relative for computation are described in details invehicle benefits afforded by each engine Reference (2). The essence of the procedurecandidate. is discussed below.
For a combat vehicle, operational Presented in Figure 20 is a flow charteffectiveness becomes combat effectiveness summarizing the principal steps involved inand one propulsion engine candidate is judged computing and comparing the cost/combat
* to be more effective than another if it can be effectiveness of combat vehicle engines. The
COST/COMBAT EFFECTIVENESS METHODOLOGYPROPULSION SYSTEM
i Ip, 5 p.(nIonl muu UNIT AND
c MAINTAINED F
(NoONA CT/CU)S
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- .. Methodology -
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1-51
branch on the left computes the number of vehicle and engine. Such a result is shown invehicles available for combat, NA, with each block 10. A similar methodology for tacticaltype of engine for a fixed budg allcation, vehicles exists but is not discussed in thisCr, and the branch on the right computes the paper. The above methodology, whenp ilty of successfully completing the employed to evaluate engines for vehiclemission, PSS, for the combat vehicle applications provides guidance for the R&Demploying each candidate engine. These two efforts by identifying the factors which bestparameters, number of engines available, NA, promote overall vehicle cost/combatand probability of success, PS, are multiplied effectiveness. in turn, the results of theseIn Block 8 to yield the number of vehicles evaluations provides management with the(with each type of engine) successfully documentation needed to justify the allocationcompleting the combat mission, Ns. The last of R&D resources to those areas indicating thestep (Block 9 or 10) shows how the results can highest return on R&D investment.be presented comparing two different enginecandida4es, A&B. This comparision is the CONCLUSION"bottomine" result being sought for decision-making purposes. Because of this importance, The US Army Tank-Automotiveit is useful to discuss these results in detail Command (TACOM) has developed an engine
The graph on the left in Block 9 presents research , development, and acquisitionthe number of vehicles successfully strategy that is intended to better focus thecompleting the combat missions as a function limited DOD resoures and to complement theof the vehicle exposure distance (i.e., distance research and development of otherbetween protected defilade positions), a key organizations. This strategy is two-fold: Firstengagement parameter. For illustrative while continuing to monitor and utilize, aspurpose, the graph shows that the eost/imbat appropriate, other engine research, TACOM iseffectiveness of the two engine candidate concentrating its limited R&D resources oncrosses over as distance increases. This high power (2- 500 HP) regenerative gas turbinehappens because the probability of survival is and adiabatic diesel engines using a1.0 for small distances and therefore, the commercial base, if possible. TACOM willnumber of surviving vehicles is controlled by continue to exploit commercial engines withNA, the number of available vehicles. NA in slight military modifications, as necessary, fortmA'n, is affected by engine availability and low power (,c 500 HP) ground vehicle
" unit life cycle engine (vehicle) cost, as shown applications.In the Blocks 1,2, and 4. The second part of the strategy is a
At longer exposure distances, the propulsion system methodology which has beenprobability of successfully completing the developed to evaluate the enhancement ofcombat mission, PS, dominates over the vehicle cost/combat effectiveness afforded byeffects of the number of vehicles available for candidate engines. The methodology providescombat, NA. The probability of successfully for the identification of some of the majorcompleting the mission is affected by the goals for the research and developmentacceleration and resulting velocity for each of program. This methodology will be furtherthe two candidate systems. The effect of developed and used as an evaluation screeningother engagement parameters, such as threat tool to determine objectively the mostweapon, range or defensive tactics, also affect promising engine alternatives warrantingthe probability of survival of each system. further development, test and evaluation.
The graph on the right in Block 9 showsthe effect of budget allocation on cost/combat ZFRUUWCEBeffeetivenenss offered by each enginecandidate. In this graph the distance traveled 1. M. Dowdy and A. Burke, "Automotive'Is fixed and the number of vehicles (with eachengine) socessfully completing the combat Technology Projections, SAE paper 790021,missions, N8 is computed as a function of thebudget allocation, CT.bary, 1979.
An alternate method of presenting theresults s to calculate the ratio of N /C (for 2. P. Glance and H. Cohen, "Evaluation
*'. a fixed distance) for engine candidates I andB divided by the value of Ns/CT for the of Engine Designs SAE paper 6 presented
" beline vehicle with a baseline engine. It hasthe advantage of indicating the relative at ta 1982 SAE International Congress andImprovement in. cost/combat effectiveness ofeach candidate in comparison to the base Exposition, February 22-26, 1982.
' .
1-53
COMBUSTION FUNDAMENTALS RESEARCH FOR GAS TURBINE ENGINE
EDWARD J. MULARZ
Head, Combustion Fundamentals SectionNASA Lewis Research Center and
* Propulsion Laboratory, USART.
The combustion research and technology programs that areconducted and managed by the NASA LeRC Combustion Branch covera wide spectrum of activities, from fundamental studies ofcombustion phenomena to applied research efforts on gas turbinecombustors. The focus of these programs is to provide thefundamental information, analytical models, and genericinformation to designers of future gas turbine engines.
The combustion research portion of the AVRADCOM PropulsionLaboratory research program is completely integrated into theNASA research program, providing both personnel and resources.
Over the last few years increased emphasis has been placedon fundamental and generic research at LeRC with less systemsdevelopment efforts. This is especially true in combustionresearch where the area of combustion fundamentals has grownsignificantly in order to better address the perceived longterm technical needs of the aerospace industry. The mainthrusts for this combustion fundamentals program are as follows:
Analytical Models of -ombustion ProcessesAnalytically characterize the governing physical phenomenawhich occur during combustion and in the fluid dynamicprocesses associated with gas turbine combustors.
Model Verification Experimen'tsProvide benchmark quality data to assess the accuracy! ofanalytical models and to identify model deficiencies.
Fundamental Combustion ExperimentsAchieve a more complete and basic understanding of thefundamental aerodynamic and chemical processes occurring inchemically reacting flows.
Advanced Numeric TechniquesImprove computer codes in terms of efficiency, numericalaccuracy, and display of results.
In each of these areas there are several research projects,including grant activities, contracts, and in-house projects.A review of these projects was recently held at LeRCl and a
* conference publication with project summaries will be* published. This presentation will give an overview of the
program with several projects highlighted as examples of theprogram.
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ARMY MOBILITY ENGINE-FUELS R&D INTERFACE
S. J. Lestz
U. S. Army Fuels and Lubricants Research Laboratory
Southwest Research Institute
San Antonio, Texas
ABSTRACT
This presentation discusses the engine-fuel interface as related to present andfuture Army mobility equipment systems. Improved engine-fuels utilization is notonly an Army/DOD objective, but a national energy goal. To achieve this goal in amost effective manner requires an interdisciplinary understanding by both fuels andengines developers. The Army is concerned with development of more fuel-tolerantengines (a long-term goal), and improved fuels' availability (a short- to long-termgoal). Both problems require cooperative efforts on behalf of the engine and thefuels developers. This presentation looks at ways in which Army fuels and enginesresearchers interface as they work towards improved engine-fuels utilization.
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1-88TABLE 4-Fuel effects on spark-ignition
TABLE 1-Primary quality factors for performancemobility fuels
Performance problem Probable fuel-related causesFuel Engine tye
quality Spark- Compression- Excessive engine wear High sulfur contentfactor Ignition ignition Turbine Dirt (silicon) contamination
Poor combustion Inadequate octane numberCombustion Octane No. Cetane No. Luminosity Hayed otmnto
Heavy ends contaminationVolatility Startup and Low temp. Nozzle Preformed gum impurites
driveability fluidity operation Poor cold starting Improper volatility controlWater contamination
Cleanliness Particulates Particulates Particulates Hot fuel problems Improper volatility controlDeposits Water and Trace metals Carburetor/induction Heavy ends contaminationEmissions sediment. Surfactants system fouling High sulfur content
Water Prelormed gum impuritiesSoluble metal contaminants
Filter plugging Water contaminationTABLE 2-Fuel properties needed for Dirt (silicon) contaminationacceptable performance Spark plug louling High aromatics content
Fuel Property controlled for given fuel type TABLE 5-Fuel effects onperformance Automotive Diesel Turbine compression-ignition performancerequired gasoline fuel fuel
Handling and Volatility Flash point Flash point Performance problem Probable fuel-related causesstorage Vapor press. Viscosity Viscosity
Contamination Conta.nination Contamination Poor combustion, Low cetane number(water sedi.) (water/sedi.) (watertsurfac.) smoking Water contaminationCopper corr. Copper corr Particulates Improper cloud point
Cloud and Microbiological Lighter/heavier fuel contaminationpour point growth Igtrhairfe otmntoExcess cylinder wear Fuel dilution
Combustion Octane No. Cetane No. Luminosity High sulfur contentDistillation Distillation Hydrocarbon Dirt (silicon) contamination
range range composition Injector nozzle Soluble metal contaminantsGravity Gravity Thermal stab. plugging/wear Heavy end impuritiesHydrocarbon Heat of Heat of Peformed impuritiescomposition combustion combustion .Preformed gum impurities
Injector pump High sulfur/hetero-atom contentCleanliness Sulfur Carbon resid Trace metals fouling/slicking Heavy ends contamination
during use Existent gum on 10% btms Distillation Gasoline contaminationStability Ash Sulfur Low fuel viscosity
Sulfur Existent gur Filter plugging Water contaminationStability Stability Fuel impunties
Improper cloud pointThermally-reactive hydrocarbons
Excess engine Heavy ends contaminationTABLE 3-Fuel quality affecting engine deposits Low cetane numberperformance High sulfur/hetero-atom content
TABLE 6-Fuel effects on turbineFuel development and use performance* Changes in refinery feedstock/product slate0 Incorporating variable quality specification concepts
a Use of emergency fuel specification Performanc problem Probable fuel-related causes*- Use of waiver/of-specification product Poor combustion Low luminometer number
* Controlled product contamination (i.e., blending pipe line Low smoke pointinterfaces) High aromatics content
a Use of substitute fuels High carbon residue values
Heavier fuel contaminationEnvironmehtal factors Excess linertblade High fuel viscosity4 Product delerioration deposits, hot end Low hydrogen content5 Uncontrolled product contamination distress High sulfur/hetero-atom content0 Ground water leakage High aromatics contentSoluble metal contaminantsa Insdequate housekeeping procedures Nozzle plugging/wear High particulate contamination0 Microbiological growth Solble metal contaminantsa Unusual ambient temperature Heavy end impurities* Changes in storage environment Marginal thermal stability
High sulfur contentFuel control system High sulfurlhetero-atom content
Extracted from: "Fuel Properties Vs. malfunction Heavy ends contaminationThermafly-reactive hydrocarbonsEngine Performance" by M. E. LePerL, Low fuel viscosity
Hydrocarbon Processing, 3anuary 1982. Marginal lubricityFilter plugging Water contamination
Surfactant contaminationMicrobiological growthFuel impuritiesImproper freeze pointThermally-reactive hydrocarbons
1-89
400-Lof .g trip economy
Carturetor icing
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300-
VaporlockDilution
DepositsHot Gum
War-u Plug fouling
Acceleration & power
100 j*------------Smoothness-_ ___
r __ ------ Short trip economyCold starting
0 10 20 30 40 50 80 70 S0 g0 100% Evaporated
Fig. 1 -Relation of gasoline distillation range to engine perfor-mance.
TABLE 7-Fuel tolerance of Army engines(Listed In order of decreasing tolerance, I.e.,Increasing order of sensitivity)
Engine type Representative engine
Gas turbine, recuperated AVCO-Lycorring AGT-15004-Cycle. liquid-cooled. divided Continental LDT-465
chamber, mufltuel4-Cycie, liquidi-cooled, indirect Caterpillar 3206
iniection4-Cycle, liquid-cooled, direct Cummins NHC 250
injection4-Cycle, air-cooled, direct Continental AVDS-1790
injection2-Cycle. liquid-cooled, direct Detroit Diesel 6V53-T
injection
* TABLE 6-Uniqu, requirements for Armyfuels
e Survivability by reducing or eliminating fuel fire hazards0 Commonality of fuela: NATO standardization, inleroperabilitya Enhanced storage stability
* C Multipurpose use-low* and high ambient temperaturese Specific fuel inhibitors0 increased combustion elfficiency and high energy potential0 Potential for emergency fuel applications
-Extracted from: "Fuel Properties Vs.* Engine Performance" by M. E. LePera,
Hydrocarbon Processing, January 1982.
D-R122 843 ENGINES/FUELS WORKSHOP t-8 DECEMBER 1982 SAN ANTONIO 21f 1TEXAS(U) SOUTHWNEST RESEARCH INST SRN ANTONIO TX ARMYFUELS AND LUBRICANTS RESEARCH LAB D M MANN ET AL. 1982
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Sesi jAOCOMBUSTIoN RESEARCH
Chairman: D. M. MannU. S. Army Research OfficeResearch Triangle Park, NC
2-3
ABSTRACT
TRANSIENT CATALYTIC COMBUSTION
Richard 0. BuckiusDepartment of Mechanical and Industrial Engineering
Richard I. Masel
Department of Chemical Engineering
University of Illinois at Urbana-ChampaignUrbana, IL. 61801
Considerable attention has been recently given to the use of catalysts indiesel engines. The objectives of the present effort are to determine kineticdata for hydrocarbon fuels for various catalysts and to model heterogeneousreactive fluid mechanics from a transient viewpoint. Experimental data obtainedto date indicates that the kinetics of formaldehyde can be modeled as decomposinginto CO and H2 on the surface of the catalyst and then CO and H2 burn as though
no formaldehyde is present. The data for the formaldehyde can be fit by amechanism where the rate determining step is the'dissociative adsorption offormaldehyde onto the catalyst. The analytical effort to date addresses thetransient oxidation of CO and H2. The heterogeneous reactive flow over a flat
plate subject to various boundary conditions have been considered. Both "light-off" and "shut-off" solutions have been evaluated. Results of these transientcalculations will be presented and discussed.
". . -. . , , . ° , • . . -o . .
a1 2-5
Basic Studies of Catalytic Combustion at UTRCP. . Marteney
United Technologies Research CenterEast Hartford, CT
ABSTRACT
The catalytic combustion program at UTRC is aimed at determining specific surfacereaction rates of hydrocarbon fuels in the catalytic combustor. Theusually-competitive, gas-phase reactions are suppressed by a low reactiontemperature. The surface reactions, plus transport of heat and mass, are treated inan analytical model. Studies to date have yielded the reaction rate of CO (which isan intermediate in the hydrocarbon oxidation) and the rates of reaction of a numberof lighter hydrocarbons. Current emphasis is on the system of two-fuel mixtures andon mixed-component surfaces such as platinum-family metals supported on rareearth oxides. An important finding in two-fuel mixtures is that methane, which isusually very slow to react, is substantially oxidized in mixtures of methane andpropylene or ethylene.
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2-17
TURBULENCE-COMBUSTION INTERACTIONS IN
LAMINAR AND TURBULENT PREMIXED METHANE-AIR V-FLAMES
Tau-Yi Toong
Massachusetts Institute of Technology
The main objective of this study is to examine the mechanisms of turbulence-
combustion interactions in premixed V-flames stabilized behind a cylindrical
flameholder. Instantaneous temperatures have been measured across the flame brush
by the use of 25 pm-diameter Pt/Pt-10 Rh thermocouples at different equivalence
ratios and different distances from the flameholder. Turbulence-generating grids
of different mesh size have also been used in order to investigate the effects of
turbulence scale and intensity.
As the thermocouple is moved across the flame brush from the unburned side,
temperature fluctuations start to appear with accompanying increase in the mean
temperature. Within the flame brush, fluctuations of larger amplitudes and higher
frequencies are observed. In the burned gases, however, fluctuations are
essentially absent, implying the importance of chemical reaction rate within the
reaction zone in triggering and sustaining these fluctuations.
By the use of two thermocouples spatially separated at a fixed distance, it
is possible to detect the movement of the flame brush at rather low frequencies.
This movement could be due to the presence of large-scale eddies or wrinkling,
resulting possibly from hydrodynamic instability.
The presence of turbulence-generating grids at the burner exit leads to large
amplitudes of the high-frequency fluctuations within the flame brush. The main
difference between laminar and turbulent flames seems to be in the relative
amplitudes of these fluctuations. This effect is more pronounced with coarser
mesh size of the turbulence-generating grids.
Near the flameholder, the amplitudes of the temperature fluctuations across
the flame brush are rather small. As the observation station is moved farther
downstream, the flame brush becomes thicker with accompanying increase in the
amplitudes, suggesting the development of instabilities due to chemical reaction
within a flame kernel as it moves downstream from the recirculation zone behind
the flameholder. This effect becomes more significant as the equivalence ratio
approaches the stoichiometric value.
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2-18
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THERMOCOUPLE
THERMOCOUPLESUPPORT
FLAME BRUSH
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BURNER EXIT
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TURBULENCE GRID
FUEL AND OXIDIZER
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MEAN AND RMS TEMPERATURE PROFILES - LAMINAR FLAME
FS.1
2-24
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4 mesh grid Tv = 3, 35, 50, 70 mm
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MAN AND RMS TEMPERATURE PROFILES ACROSS THE FLAME BRUSH - TURBULENT FLAME;4 MESH GRID AND 10 MESH GRID
2-25
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0ID0 20 40 60 80DEVELOPMENT OF MAXIMUM RMS TEMPERATURE FLUCTUATIONS (ALL-PASS AND HIGH-PASS)
FOR LAMINAR AND TURBULENT FLAMES WITH DIFFERENT MESH SIZES OF TURBULENCE-
GENERATING GRIDS r.. 5
2-27
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2-29
PREIGNITION OXIDATION CHARACTERISTICS OF HYDROCARBON FUELS
Richard S. Cohen and Nicholas P. CernanskyDepartment of Mechanical Engineering
Drexel University, Philadelphia, PA 19104
Program Summary
Ignition is a complex process involving preignition reactions
which lead up to the point of hot ignition. It is the preignition
behavior of the system which determines whether or not ignition occurs.
An understanding of the global preignition oxidation mechanisms, the
associated heat release rates, and the controlling fuel and physical
factors will become essential when synthetic and poorer quality petro-
leum fuels come into wider use.
Consequently, in April 1980, a study of the preignition behavior
of hydrocarbon fuels was initiated under the sponsorship of the Army
Research Office (ARO Numbers: DRXRO-EG-16957; DAAG 29-80-C-0112).
The specific objectives for the study are:
(1) to determine the quantitative and qualitative factors important
to ignition delay for a variety of fuels; and
(2) to determine the global oxidation mechanisms and heat release
rates for these fuels during the preignition reaction process.
The experimental program utilizes gas chromatographic profiling and
analysis techniques to qualitatively and quantitatively assess the
reactants, products, and stable reaction intermediates during the preig-
' nition oxidation process. These species are being followed in time up
to the point of hot ignition in a static reactor test facility exercised
over a range of operating conditions. Analysis and interpretation of
these data will lead to attainment of the above objectives.
Work to date has focused on developing and verifying the experimental
and analytical systems and on carrying out exploratory and preliminary
measurements in the system. Reproducibility of the system has been
established and anticipated effects of temperature and pressure have been
* confirmed. The ability to follow the distribution of products and stable
intermediates over the course of reaction has been demonstrated. Currently,
additional verification work is underway and detailed testing of pure
fuels and pure fuel blends, with and without additives, will commence
shortly.
2-30
PREIGNITION OXIDATION CHARACTERISTICS
OF HYDROCARBON FUELS
RICHARD S. COHENNICHOLAS P. CERNANSKY
DEPT. OF MECHANICAL ENGINEERINGDREXEL UNIVERSITY
PHILADELPHIA, PA. 19104
.',4
UO
2-31
PROGRAM TO STUDY THE PREIGNITION OXIDATION
CHARACTERISTICS OF HYDROCARBON FUELS
OBJECTIVES
. TO EXTEND AND COMPLIMENT PREVIOUS WORK
-DEVELOP SPECIES INFORMATION DURING PREIGNITION
PROCESSES
-INCLUDE HIGHER CARBON NUMBER FUELS
-EXAMINE THE EFFECTS OF FUEL MIXTURES AND ADDITIVES
• TO DETERMINE GLOBAL OXIDATION MECHANISMS AND
HEAT RELEASE RATES
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2-37
SUMMARY AND CONCLUSIONS
* A STATIC REACTOR FACILITY AND A CHROMATOGRAPHIC
PEAK PROFILING SYSTEM HAVE BEEN DEVELOPED FOR STUDYING
THE PREIGNITION OXIDATION BEHAVIOR OF HYDROCARBONS
* PRELIMINARY TESTING HAS BEEN CARRIED OUT
-SYSTEM OPERATES REPRODUCIBLY
-TEMPERATURE PROFILES ARE CONSISTENT WITH THE
EXPECTED BEHAVIOR IN THE COOL FLAME REGION
-INCREASING INITIAL PRESSURE AND TEMPERATURE PRODUCLEi
THE EXPECTED SHORTENINI OF THE INDUCTION PERIOD
-THE DISTRIBUTION AND NUMBER OF STABLE REACTION
INTERMEDIATES AND PRODUCTS ARE AFFECTED BY OPERATINGCONDITIONS AND CAN BE FOLLOWED DURING THE COURSE
OF REACTION
U[-
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P.7
2-38
CURRENT AND FUTURE WORK
* QUANTIFICATION OF SURFACE EFFECTS
* MODIFICATIONS TO PERMIT THE USE OF LIOUID FUELS
* DETAILED TESTING OF PURE FUELS AND PURE FUEL BLENDS,
WITH AND WITHOUT ADDITIVES
* IDENTIFICATION OF IMPORTANT SPECIES AND
DETERMINATION OF MECHANISMS
3-1
Session 3ARO DIESEL ENGINE RESEARCH
Chairman: P. C. GlanceU. S. Army Tank-Automotive Command
Warren, MI
DIESEL SPRAYS
Norman Chigier
Department of Mechanical EngineeringCarnegie-Mellon University
Pittsburgh, PA 15213
The main objective of this research is to establish the basic mechanismsof atomization and vaporization in pulsed diesel sprays. Characterizat.ionof diesel sprays requires measurement of particle size distribution andparticle velocity as a function of space and time. High speed cinematographyprovides visualization of global features of the spray as it penetrates intothe air flow field. Laser induced fluorescence will allow study of motion
* of sections of the spray and of individual drops. A major problem is todifferentiate between the presence of drops in a dense spray and the pre-
sence of bulk liquid, ligaments and large agglomerations of drops. Becauseof the high density of the sprays, laser light obscuration can be of theorder of 90%, causing great difficulty in using pulsed laser imaging techni-ques and laser interferometric methods for particle sizing and velocity
measurement.The Malvern instrument yields measurements at laser light obscuration
as high as 90% but calibration and interpretation of the measurements isrequired due to multiple scattering and interference effects. X-rays andultraviolet radiation would allow greater penetration through the densesprays; the feasibility of extending flash imaging techniques to these regionsof the energy spectrum needs exploring.
a The diode arrays in the Malvern instrument are multiplexed as the inten-sity is measured in each diode sequentially. This sequence of events is
*too long for measurements to be made in diesel sprays with lifetimes of the*order of 10 ins. By simultaneous recording of time histories from each diode,a for several pulses of the spray, the light intensity distribution can be
reconstructed to yield drop size distributions as a function of time, afterstart of injection, at a particular location in the spray. Initial attemptsat making such measurements have demonstrated the feasibility of using the
V
' 3-4
Diesel SpraysN. Chigier
Malvern for drop size measurement in diesel sprays but further development
- is required to improve accuracy.
Trajectories of individual drops determine the location of depositionof fuel vapor and hence the distributions of local fuel vapor/air ratios.
* Since soot formation is promoted in fuel rich regions with high temperature
* . gradients, knowledge of profiles of temperature and gas concentration enablethe identification of soot forming regions within the spray flame. Since
* . soot burning is promoted in regions of lean mixture ratio with high tempera-ture and residence time, knowledge of temperature and gas concentration pro-files also enable identification of soot burning regions within the spray
- . flame.
A high pressure, high temperature chamber has been designed to studydiesel sprays injected into air environments simulating conditions in the
engine cylinder prior to ignition. An electromagnetically controlled injectorhas been acquired from GM for controlled injection of fuel into the chamber.
A Malvern particle sizing instrument has been purchased and is undergoing
calibration. A High-cam, high speed motion camera is available for visualiza-
tion studies.
,3-5
OBJECTIVES
FUNDAMENTAL STUDY OF ATOMIZATION OFPULSED DIESEL SPRAYS
CHARACTERIZATION OF DIESEL SPRAYS BYDETERMINATION OF DROP SIZE AND VELOCITYDISTRIBUTIONS
ESTABLISHMENT OF TRAJECTORIES OFINDIVIDUAL DROPLETS OF VARYING SIZE ANDMOMENTUM WITHIN SPRAY
MEASUREMENT OF RATE OF VAPORIZATION OF rDROPLETS AS A FUNCTION OF AMBIENTTEMPERATURE, PRESSURE, AND FUEL VAPORCONCENTRATION
DETERMINATION OF LOCAL FUEL-AIR MIXINGRATIOS AND THE EFFECT ON SOOT FORMATION
r '1CA
• "7 ". L• .I ,lm~m d
3-6
FUNDAMENTAL QUESTIONS
WHAT IS THE LIFETIME OF LIQUID FUEL DROPLETSIN DIESEL ENGINE CYLINDERS.
HOW DOES ATOMIZATION INFLUENCE SPRAY
CHARACTERISTICS AND VAPORIZATION.
TO WHAT EXTENT DO LIQUID PARTICLES IMPINGE
ON SOLID SURFACES.
HOW DO VARIATIONS IN LOCAL VAPOR FUEL/AIRRATIOS AFFECT SOOT FORMATION ANDOXIDATION.
3-7
INSTRUMENTATIONII
HIGH SPEED SCHLIEREN MOTION PICTURE
PULSED LASER PHOTOGRAPHY AND HOLOGRAPHY
LASER DOPPLER ANEMOMETER ANDINTERFEROMETER
LASER DIFFRACTION PARTICLE SIZER
X-RAY FLASH RADIOGRAPHY
MICROTHERMOCOUPLES
- . V
.°7
3-8 Injector
~ ** Dilute Low VelocityF . ~ ~:* *Tail and Periphery of Spray
4.1'1
Dens Core
Al Moderate Velocity11 10 ms-i
Ver Hig Velocit
Liaet VeyHgMeoirttAl Front of Spray
100 ms-i
SCHEMATIC DIAGRAM OF ZONES OF TYPICAL SPRAY PULSE
3-9
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3-11
ARO/MERADCOM Engines/Fuels WorkshopSouthwest Research Institute
San Antonio, Texas, Dec. 7-8, 1982
Atomization and Thick SpraysDAAG 29-81-K-01 35
F.V. BraccoPrinceton University
ABSTRACT
Sprays are considered from single cylindrical orifices under the cor:-ditions of direct fuel injection in internal combustion engines.
The main conclusions of earlier measurements pertaining to the 40L breakup process are summarized first (p.2). From them it is possible to computethe spreading angle of the spray at the nozzle exit and the average size ofthe drops formed by the break-up of the outer surface of the jet near thenozzle exit.
Measurements are then reported of the axial component of the drop velo-city 2 to 12 cm from the nozzle. The measurements were made by LDV undervarious conditions and at several radial and axial locations (pp.3 -5).
Starting from the initial angle and drop size at the nozzle exit, thedownstream drop velocities were then computed with an advanced spray model andcompared with the measured ones (pp.6-8).
A brief summary follows of our current understanding of the structure ofthese sprays (p.9 ).
Finally, this and related studies led us to some questions about engineflows and combustion that are put forth as our contribution to the generaldiscussion (p.10).
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.3-12
ta8 1 1/2ta - (Pg/P)(1
x iC a/P (2)V t g inj
JET BREAKUP
The break up of the outer surface of the jet occurs on the time scale ofmicroseconds and therefore is quasi steady with respect to the changing engine
* conditions [1). This breakup starts in the immediate vicinity of the orificeexit. Aerodynamic interaction between the liquid surface and the gas induces
* rapid and selective growth of perturbations that originate .thin the nozzle[2]. The initial angle of the spray is thus set and found to depend moststrongly on the nozzle design and the gas-to-liquid density ratio as shown in
* Eq. (1) in which A is a constant for a given nozzle design (3]. The initial* size of the drops formed by the breakup of the outer surface of the jet is
determined by the Weber number and is insensitive to the nozzle geoemtry asshown in Eq. (2) in which i is the volume-mean drop diameter and C w 10 (4].
The mechanism by which the nozzle geometry influences the breakup of theouter surface of the jet and the mode of break up of the inner core of the jetare not known at present.
7!1
3-13
Pg pg/pt Ap Vin j Nozzle X/D
(KPa) (HPa) (m/s) d 0m) L/D
1.48 0.0256 11.0 127 127 4.0 300,400,600,800
4.24 0.0732 11.0 127 127 4.0 300,600
4.24 0.0732 26.2 194 127 4.0 400,500
1.48 0.0256 11.0 125 76.2 1.0 300,500
4.24 0.0732 11.0 125 76.2 1.0 300
Liquid: n-hexane pp - 665 kg/m3
Gas: nitrogen Ul - 3.2x10-4 N.s/m2
at 1.84 x 10-2 14/m
Table 1
DROP VELOCITY MEASUREMENTS
Using an LDV system, radial distributions of the axial drop velocitieswere measured at several axial locations within steady, isothermal sprays,including regions with very high drop number densities () 1011 m-3) and velo-city gradients (up to 5 m/s per mm). The LDV system consisted of: an argonion laser at 514.5 nm; dual beam, 900 scatter mode; 0.2x0.2x0.7 mm3 probevolume; 6.17 Um fringe spacing; no frequency shift; counter signal processor.The minimum distance from the nozzle was 300 nozzle diameters (2.3 cm). n-hexane was injected into cospressed nitrogen at two injection velocities (127and 194 m/s) and through two single-hole round nozzles of different diameter
*(127 and 76.2 lm) and length-to-diameter ratio (4 and 1). Two ratios of thegas density to the liquid density were used (0.0256 and 0.0732). The test
"| conditions are summarized in Table 1.
rp
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3-14
wipe& @11,I 300 @11,01 C44 |
11 11.0o\• 1. 40
• 2 4.2440 142.4 1.464 O no
IAB 11 J4 0-4 ...4 * m .jet > .4 Incomprelble jet
.2 .2
0
o o0 .5 1 1.5 2 2.5 3 0 .05 .1 .15 .2 .25 .3
FIG. I r/r FIG. 2 r/x
1 1
Nozle I o (f ,fVlnI) - o.o256o (f'g/f lnJ) - 0.0732
.8 2 (PV/eN) - 0.0256Nozzle 2
0 0 (Pg/Pinj) - 0.0732
6*
4)
Nozzle 1 0 (fV lD - 0.05-• * 0 (fgflnJ) - 0.0732
.2 * Nozzle 2 (P/LVlnJ) - 0.0250z (f J/flnJ) - 0.0732
0 1 J 1J -2 26 2 4 6 a 10 12 14 10 10FIG. 3 x (cm) FIG. 4 X/d
The measured radial distributions of the mean and fluctuating componentsof the drop velocity were found to be very similar in trends and magnitudes tothe corresponding distributions of the fluid velocity in the far field ofincompressible jets (Figs. 1,6-8). Thus the drop velocity field tends to theuniversal fluid velocity field of incompressible jets. However, whereasincompressible jets achieve their self preserving configuration, some 50diameters from the injector [5], the drop velocities achieve a similar con-figuration more than 300 diameters from the injector in these dense, non-vaporizing sprays (Figs. 2,3).
1i
3-15
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0 (fpl/fi) - 0.0732
Noze (V f, J) -M o4o7"
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1(i 1-- N ' '* I) I~ I I I
1 2 2
8. .2
10 120 .5 1 1.5 2 2.5 3FIG. 5 d)FIG. 6r/r
5 12
4 10 Z 4 1,0 14 Ou4 lJ 4.24 -4600 11.I 10 11
5 " • eie -§ IA1
4- I q_ i I
0~ .5 16 value5 I I
2 2
-1-
09
0 .5 1 1.5 2 2.5 30 .5 1 1.5 2 2.5 3FIG.? 7r/r FIG. 8 "/N
The greater is the density of the injected fluid with respect to that ofthe environment, the slower the decay of the jet velocity and the faster thepenetration (Fig. 4). It is as if the axial scale of the jet is stretchedproportlonally to (pt/pg)n where n tends to 1/2 in the far field [61, to Inear the injector (7] and may be close to 3/4 in the range of our measurements(Fig. 5). Details of these measurements are in 110].
21 .r 7
3-16
VAPOR MASS FRACTIONVELOCITY AND DROP PARCELS AND GAS TEMPERATURE
YV....................................... iii ii,t= I ms t 1.2 ms
T
.............. .....................i Yv
t:2 ms t =.2.4 ms
T
Yv
t:3 ms t :3.6 ms
T
FIG.9 b)
DROP VELOCITY COMPUTATIONS
Having the initial angle and drop size, computations can be made of thesubsequent development of the spray and the computed downstream results com-pared with the corresponding downstream measurements. The initial drop sizeis randomly selected from a distribution with mean value given by Eq. 2, andthe initial angle of the drop velocity is randomly selected from a distribu-tion between zero and that given by Eq. 1.
3-17
o COMPUTED DROP0 9 MEASURED DROPA& COMPUTED GAS
22
a 0 400X/D
- aa
00
0 40 00 X/D
0 02 0.4 0.6 08 LO 12
RADIAL DISTANCE (cm )
The model is for fully coupled two-dimensional unsteady two-phase flowsand attempts to account for the effect of gas volume fraction on mass momentum
and energy transfer rates between the two phases, for drop collisions and
coalescence, and for turbulence effects on drops and gas (81. Typical com-puted spray structures are shown in Fig. 9: a) drop parcels and gas velocityof a non-evaporating spray; b) gas temperature and vapor mass fraction con-tours of a vaporizing spray 19].
Comparisons of computed and measured quantities are shown in Figs. 10-16.The parameters of this spray are given in the first row of Table 1. The con-puted mean axial velocity of the drops agrees reasonably well with the measured
-* one at all radial and axial locations (Fig. 10). Correspondingly there is
7- r
3-18
o COMPUTED DIIOPe MEASURED WnOP
& COMPUTED GASa C OPUTED DROP0 MEASURED OOP 0
600 00
000.
2 3 200 400 GOD GooI0FIG. II 66.) FIG, 12 m/D
I @W;01 300 X/D300XD + .400 X/DS4010 400 K/DO KO Wdo goo 0 X/t
00l N4 4ob . ,
Vtt
COMPUTED MEAN AXIAL GAS MELOWY 0 COMPUTED MEAN XIAL. O bELDCITY0 or 0 __
1 2a I,
FIG. 13 FIG. 14
3 30C .1
& 300J / O400 X/K
0 0 n 0 OO X/O 0 K
To ItoN I
to t t
COMPUTED FLUCTUATPiN OF Tef AXIAL GAS ViCITY COMPUTED FLUCTUAT04 OF TE AXIAL DROP1 1 EL.OCVTVr
FIG. I5 2 .5 1t~r.. FIG isr
good agreement also in the centerline velocity decay (Fig. 11) and the sprayhalf-width (Fig. 12). In the computations, as in the experiment, the meanaxial velocity of the drops achieves a self similar profile (not imposed apriori) and so does the mean axial velocity of the gas (not measured). Themean values of the drop and gas velocities are computed to be nearly equal(Figs. 10, 13, 14) even though no restrictions were imposed on them a priori.Fig. 15 shows that the computed turbulent fluctuations of the axial componentof the gas velocity are close in distribution and magnitude to those measuredin the far field of incompressible jets (a k-e model for the gas turbulence isused in the model). But the computed fluctuations of the axial component ofthe drop velocity are about a half the measured ones (compare Fig. 16 and 6). -
,U i .. - -i I '. i"- . . .. . ..i .. .. .......... .. .. . . .. ..... ..-.... .
-j3-19
-C CONCLUSIONS
The breakup of the outer surface of fuel jets in Diesel-type conditionsstarts in the immediate vicinity of the injector and yields initial sprayangle and drop sizes that can be estimated with acceptable accuracy. The modeof breakup of the core of the fuel jet is still unknown.
A non-vaporizing steady spray attains the typical self preserving struc-ture of turbulent jets some 300 nozzle diameters, i.e. 3 to 12 cm, from theinjector probably because at that distance most of the jet mass is entrainedmass. Mean drop and gas velocities are then nearly equal but their fluc-tuating components are very large (- 30%) and not necessarily in phase.Vaporizing sprays should develop closer to the injector since the axial lengthscale decreases with decreasing (effective) density of the injected fluid.Even so, the development region remains the one of prime interest in engineapplications, particularly since the properties of the ambient gas changeduring the propagation of the spray.
A recently developed model for transient sprays has reproduced satisfac-tory all measured downstream steady mean properties but not the fluctuation ofthe axial component of the drop velocity. The steady far field was obtainedintegrating through the transient and the development region. The goodagreement with the steady farfield does not prove that the transient and thedevelopment regions themelves are reproduced accurately, but it lends supportto such possibility. Moreover earlier comparisons with nearfield tip penetra-tion rates and far field drop size measurements in different conditions werealso satisfactory [7). In all, so far the model has performed above expec-tations, but the discrepancy in the fluctuation of the drop velocity points tothe need for refinements.
3-20
REFERENCES
I. Reitz, R.D. and Bracco, F.V., "Ultra-High-Speed Filming of AtomizingJets", Physics of Fluids, 22, 6, pp. 1054-1064, June 1979.
2. Reitz, R.D. and Bracco, F.V., "On the Mechanism of Atomization of aLiquid Jet", Physics of Fluids, 15, 10, pp. 1730-1742, October 1982.
3. Reitz, R.D. and Bracco, F.V., "On the Dependence of Spray Angle and OtherSpray Parameters on Nozzle Design and Operating Conditions", SAE Paper790494, February 1979.
4. Wu, K.-J., "On the Structure of Sprays from Cylindrical Orifices", Ph.Thesis, Department of Mechanical and Aerospace Engineering, PrincetonUniversity, in preparation.
5. Wygnanski, I. and Fiedler, H., "Some Measurements in Self-PreservingJet", J. Fluid Mechanics, 38, 3, pp. 577-612, 1969.
6. Kleinstein, G., "Mixing in Turbulent Axially Symmetric Free Jets", J.Spacecraft, 1, 4, pp. 403-408, August 1964.
7. Kuo, T.-W. and Bracco, F.V., "On the Scaling of Transient Laminar, Tur-bulent and Spray Jets", SAE Paper 820038, February 1982.
8. O'Rourke, P.J. and Bracco, F.V., "Modeling of Drop Interactions in ThickSprays and a Coparison with Experiments", The Institution of MechanicalEngineers, Stratified Charge Automotive Engines Conference (Publication085298-469), London, England, November 1980.
9. Kuo, T.-W. and Bracco, F.V., "Computations of Drop Sizes in PulsatingSprays and of Liquid-Core Length in Vaporizing Sprays", SAE Paper 820133,February 1982.
10. Wu, K.-J., Coghe, A., Santavicca, D.A. and Bracco, F.i., "LDV Measure-ments of Drop Velocities in Diesel-Type Sprays", 15th DISC Meeting, GMR,March 1982, to be submitted to the AIAA Journal.
QUESTIONS
1) Could cavitation contribute to smoke?
2) What of swirl is useful?
3) Is swirl really necessary?
4) Should hollw-cone sprays be reconsidered for open chamber Diesels?
5) Shouldn't ignition be controlled?
7
3-21
WALL EFFECTS ON COMBUSTION IN AN ENGINE
F. E. Fendell
TRW, Inc., Redondo Beach, CA 90278
ABSTRACT
Previous work quantified that flame quenching occurs near a cold wall,
whereas rapid conversion of reactants to products occurs near a hot wall.
Simple modeling and laboratory experiments are again used to elucidate
aspects of flame-wall interaction in an intermittent-burning ICE.
In a premixture, compressive heating of the residual charge may cause
so rapid homogeneous combustion (instead of smooth flame propagation) that
spatially inhomogeneous pressure occurs ("end-gas knock"). Analysis sug-
gests that augmented heat transfer from the end gas precludes explosive
burning, though a larger fraction of the charge than often envisioned must
be regarded as "end gas." Recent emphasis on chamber shape in reciprocating-
piston engines is well taken, since knock-free operation of production car-
buretored engines at compression ratio of 12.5 has been demonstrated.
Also to be presented are temperature and fuel mass fraction measurements
obtained by laser Raman spectroscopy for sidewall quenching (placing a cold
plate perpendicular to a burner-stabilized, planar, premixed flame). These
measurements indicate the (1) residual fuel near the cold sidewall is rapidly
oxidated (so crevice-type quenching is the predominant source of exhaust
. hydrocarbons), and (2) there is sufficient sensitivity to quench-surface
material and to hydrocarbon species that simplistic aerothermochemical models
4 afford only qualitative guidance.
These two studies suggest that, by design for heat transfer and chamber
geometry, smooth yet complete charge burn-up seems attainable.
r(p
I! . i. • " ' . ...
3-22
zz
0
Lr
z
-4
w "~ xK U 0 I
<W <z L)
w
lipZ
i U
h-4~f.4
OWE-4 uz~ C0
w 0 zU
u oOin
1-4 Z
r344 64 C
Ca-E-a-4ca
04-
E-4 tca4n
3-24
- 0
4-)4
4~S Cm 0-4
u 0
H Z E- H'-4
1-4 H
E- 4 Cmz z
u~c 0,~ 0
toi 01I ='-H
0a 0 a~
8 >olo
00 >a wa Fa0acn 0-
H. -4J 0 0n
14- to4g ca O
14 On
V H
0k 1 0 H
0
H 0 t
3-25
SIDE-WALL BOUNDARY/EIGENVALUE PROBLEM
o DIRECT ONE-STEP IRREVERSIBLE REACTION (0 - OXYGEN, F * FUEL, P - PRODUCT)
VO0 + VFF - vpP (ARRHENIUS KINETICS)
o MOLECULAR WEIGHT OF MAJOR SPECIES COMPARABLE
o UNIVERSAL BINARY DIFFUSION COEFFICIENT
o LEWIS-SEMENOV NUMBER UNITY
o ISOBARIC LOW-MACH-NUMBER FLOW (NO MECHANICAL DISSIPATION)
o CONSTANT UNIVERSAL SPECIFIC HEAT
o SIMPLE VARIATION OF TRANSPORT PROPERTIES WITH THERMODYNAMIC STATE
o DECOUPLING OF THE DYNAMICS AND ENERGETICS (APPROXIMATION OF FLOW FOR
CONVECTIVE TRANSPORT OF HEAT AND SPECIES)
p e
3-26
HOMOGENEOUS EXPLOSION OF A PREMIXTURE
ADOPT
v 0 0 + vF F * PRODUCTS
LEWIS NUMBER UNITY
FUEL-LEAN OR STOICHIOMETRIC (01 1)
Qf m YFuT =Tu* * .F
1 -T + ----- , m,, 0 l0 + mF Fcp mF vm
":~ Yu/Y~u
•*2 *__e * uu t
[HFvF/mOO D'e *
T = , *. TO = w , "EIGENVALUE"TffTu Tf Tu
1 [i +TO-] [(1 - ) + (1 +T O - T] e -
T(O)=-TO . T(tf) = 1*, T
SEEK TO SUCH THAT T 2 C * =0 T*
80
TAYLOR: TO - 0(1000 K)
*0
2.4C
3-27
USE OF POLYTROPIC LAW TO MODEL HEAT TRANSFER
c dT + p - q a RATE OF HEAT ADDITIONT -t (PER UNIT MASS)
IDEAL GAS:
d in T ( n di i ~
IF q -E C T , CONST.
din (p/pY). ; ., Pdt
-P exp (-ct)dt py POY
IF (p/po) - exp (lit) DURING COMBUSTION,
I.E., IF exp (-Et) (p/o ,
THEN
'Y Y >
.. , HEAT LOSSES CAN BE MODELLED VERY CRUDELY, BUT VERY ADEQUATELY FOR
CURRENT PURPOSES BY USE OF A y WHICH IS LESS THAN C /c
ap
3-28
THERMODYNAMI CS
INVERSE FUNCTION: p,(p
BULK GAS (0 < 'P< 92) END GAS (*2 <p< M)
UNBURNED GAS (p> T):
P P (P/p0)l/ p /PD (P/po)l/I
h u/ho (p/po), y1- h u/AD (p/po)o 0 B I -
JUST-BURNED GAS (' T
hJB/hO (P/po)c + (H/h0) h;B/h; (p/p0)6 (H/h0)
p/p0 'p/p 0
PJ-B' ~ H PJ-B/P0 a H+ _0~ +p0 e
BURNED GAS('
= ( 1 / 11K ... ): 0'(iI
h _.L
+ 0
3-29
SIDE-WALL ELLIPTICAL PARTIAL DIFFERENTIAL EQUATIONS
O x xt 0 z L
L* + y (32y 32 .2 yVF[ 1 r ( 1ax az 3V" X2 a)Z2 )
pu~+Vj Lx kz 2 L - 0) + oYJ expL I. -E( T)J
ax \az X2 2 L
v F+v 0 1 -V 0 -m* 0* D* YFu O exp(-) • +V I ) r(vF+ I)]
z
pu SPECIFIED; pv *- Pu dz
0
o.I
°.p
3-30-_
BOUNDARY CONDITIONS
x 0: pu C, pv O, TT 0 , Y - T WHERE I >> T > 0
32T =a2Yx ASxt: =a- =3ax- 0
K(u XaX axyaxZ L * T = pv = 0 FOR TWO-WALL DUCT
dY d 2y T 2 rC dY -2 T1 V [1-* + .Jxp (I-4Cl T)] FO R
OONE
WALL,Y Y AT x SSO; - 0 AT x - xt; T + Y L> >1
Y
Z0: T Tu WHERE 1 ?T w )TO , - 0 FOR ISOTHERMAL NONCATALYTIC WALLw azaT aY7T 0 FOR ADIABATIC NONCATALYTIC WALL
T - T0 , Y I 1 - T0 FOR ISOTHER4AL POROUS WALL
.. --
.,-i
3-31
PISTON-CRANK RELATIONSHIP
PISTON DISPLACEMENT FROM INITIAL POSITION
y(t) = D(O) - D(t)
O(t) =-R +r 1-cos e+Ra - [i , (A J }
CLEARANCE DISPLACEMENT FROM CLEARANCE
AT TDC AT TDC
B = CRANK ANGLE= 27nt + 0 n =RPM
r = CRANK RADIUS
Ra = £/r , 2 = CONNECTING-ROD LENGTH
CR = COMPRESSION RATIO
1 '
Ui ..
-- 2 T - . i .
3-32
EQUATIONS
FLAME-PROPAGATION RELATION ([f(O) *0):
CONTINUITY OF UNBURNED MASS:rL
p u J A(x, t)dx E*2
42 i(t) ~ ~~~x vt
up J~ A~dx m~d = a Y)XftXff~t)
GLOBAL CONTINUITY [V(t) V 0-~t]
v(t) d +- +v(t) A J LPB p(t) 0 wPt p?
0 ~sr(B/2) B *BORE
3-33
0
0
u0 *4I-0I..
ag U *to a.0~L E 4-..
04-3~t . -~0 4- -rD.. jL 4-- 0)ZJ . a)'D
I - E- in A
Z< 0 C4-)z c0 CA Qi.cc~ CC .
LU 0 -
0 Z I ro- c -
Z c0 1.4 U
0 L0 icLLU +J 4) 1 C
z 0 r-00a
C-J z 4J. r
30 0 inZ
w. 4 4U 0C
0/ 0u LLCL LU EU
S3r 00-41 to 0
0 *.0 Li in
o 1 EU 4- 4
Cli 0
' 0 0 E
Lj LAJ 4 C 41 4
zx Z N U09
44 - Cfa4
01 - 0 0
.0 C.4'
La. i.4 0 ]
4-11
FAWE AT t sv4 FL/.A.E AT ri#4( t
'j ~ ~ ~ ~ u 4inu ? O%7 I cCMp4 ~A a I N T A L h S T
A~~c~)= AH91~r CsS-f~O APLt 0PRI
* P r/
6R= '
t N W4
11ii
p 1
3-35
EN THA P Y -PRO'FZ L rS
-imE t~ tI>*O It .12bS'~ 0a) 'PtEsm
(SPECJPX~C HArT
t)M t)O
WI
i6'(tts L
3-36
Lu Ln
K.. LL L
LC)
CL.LA
CD co 0D-, DCCDCoDC
LO 00C=0- C; CN
uiI
0~0Cl-0E LA
NN
JLA%
0D 00 a]
a; 71
3-38
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3-41
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CD 0 0
0
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cr
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3-42
Li
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.. ........ ...... .. ....... ...... ..... ....... ..
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**0100ST 0 OS? 1 010001 olosz 0do o0 .09Z
3-43
"Diesel Engine Cylinder Gas-Side Heat Flux
to a Ceramic Surface"
G. L. Boman
University of Wisconsin - Madison
Contract No. OAAG29-81-K-0082
The research effort consists of two projects. The first project isto measure instanteous rates of heat transfer from the cylinder gas to aceramic surface in a fired diesel engine. The second project is tofabricate and test an instrument which is to measure either the totalinstanteous heat transfer or only its radiation component in a fireddiesel. Both projects will be carried out on a TACOM-LABECO singlecylinder, open chamber engine.
The heat transfer measurements will utilize a specially fabricatedhead which contains a very large instrumentation plug. The cylinderside surface of this plug is designed to accept plates of variouscandidate ceramic materials. The two materials to be tested are hotpressed zirconia and a surface sealed layer of porous zirconia. Todate, the engine head has been fabricated and is now under preliminarytest. Methods of instrumenting the ceramic surfaces have been investigatedboth in our own lab and from commercial sources. It appears that eitherthin film thermocouples formed by overlapping films or a platinumresistance film can be used. While the head was being fabricated andthe transducer being investigated, a series of base line heat transfermeasurements were conducted using a metal head and thin film thermocouples.Methodr of recording and processing the data have been developed.
The special heat transfer instrument will utilize a thin filmthermocouple to measure either total convective and radiative heattransfer or only the radiative component. When only radiation is to be
ad measured, a timed jet of heated air is directed over the surface thermo-couple. Engine testing of the device for feasibility is currentlyunderway.
U
. .. . .. . -. .o . ..° .. ., . .- . . . ; : -. .. . . i / . •
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3-44
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3-46
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3-48
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3-49
z ........
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C~~~~~J~ 00'-~CJc~ O \co w 0
'~ ~ t t (J 'J cJ -L
H >< 0D.
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3-52
Ci) iAIGINE ,'1-r~D BLOCK.
®PLLJ
40 C~tvtAC PLArE.5 CREMS To HoLo THlE pLATE ON THlE SiDE.
'TIAE EOLIAQ& VIEW=o "NS 'T\, OV PhRT ig S SP)40 BELOW:P
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4-1
A. O COMBUSIO RESEARCH
Chairman: E. Mularz0 U. S. Army Aviation Research and Development Command
U. S.Am-eerhadTehooyLbrtr
Clvlad OH
4-3
FLAME PROPAGATION IN SPRAYS
byS.C. Yao, W.A. Sirignano, S.K. Aggarwal, and N. Ashgrizzadeh
Carnegie-Mellion University* Pittsburgh, PA 15213
A joint experimental - computational study is underway on flame propagation in
* sprays. The purpose is to identify the prominent physical, dynamical and chemical
mechanisms involved in the burning of sprays and to develop a predictive capability
via computation.
An experimental apparatus has been designed, fabricated, and tested which allows
separate control of key parameters such as droplet size, fuel type, mixture ratio,
distance between droplets, droplet velocity, and air velocity. This ability to vary
independently several parameters allows a critical evaluation of any theoretical
A piezo-electric crystal is employed to pulse the volume in a fuel reservoir
immnediately behind a multi-orifice fuel injector plate. The orifice size, pulsing
duration and amplitude, and time between pulses controls initial droplet size, spa-
cing, and velocity. Air flow is carefully distributed across the spray by perforated
tubes. A wedge-shaped flame is held by a thin flameholder so that locally the flame
approximates a one-dimensional structure.
A one-dimensional model predicts that the flame is not perfectly steady. Some
* vaporization and mixing of fuel vapor with air occurs before the flame.
With sufficiently volatile fuels, a flammnable mixture results for a deflagration
* to result which does not rely on further vaporization. The liquid fuel droplets
entering the flame may or not complete vaporization before they leave the flame.
Droplet burring has been seen to occur well beyond the flame-front. Since flame
* thickness can be smaller than average distance between droplets, an unsteady situa-
F .
0
Iii 4-4
E'. tion arises. The degree of unsteadiness would increase as the fuels become less
i~m volatile, the distance between droplets increases, and the droplets become larger.
-" - In the future, experimental diagnostics and further theoretical modelling are
r intended to study this phenomenon more carefully.
4-5Suction
~ed. * *
46:4 49 L
of
/h~ eg ,4 am
,o A A.Ai Air.4..~
Fuel wa. Ejector*h
Tub 1Scemaico the SprayGenerator
4-6
N
50-
40-
30-
20-
10
100 140 180 220 260 300 340 380 420
d~m
17 FIG.2 Generated Droplet Spectrum
..- ..... . . .....
4-7
S 00
U0
F I G ( B E J E C T E D R P E S N A H E E A O L T
" 0 Oo ..S
12. • •
• ,,
-
.. ,. 0 •
. (A) DISPERSED DROPLETS IN SPRAY:
0 0
0o
0 O"
o -0
SI
!'. FIG. 3. (B) EJECTED DROPLETS NEAR THE GENERATOR PLATE -.
4-8
FIG.4 Blue Flame of Hexane Spray (150, 14m)
4- 9
r
FIG.5 (b) name of the Hexane Spray (300Alm droplet dia.)
4-10r
F
FIG.6 Flame of the Toluene Spray (300Mm dia.)
4-i1
0 0C0 0 0o 0 q. C o
0 0
0t -
6.. >.
00
0 0 1 L
E 0
it (• o 0 W%*]00
l]~ o< 0 0 I
00
-~~ L
000 00
S0 00' ' 4.' C, ,,0
• i . ,,...,. _ . , ... @. 0 6 10..... ........ . . . 0 ....
A7 D-Ai22 843 ENGINES/FUELS W~ORKSHOP 6-B DECEMBER 1982 N007TEXAS(U) SOUTHWIEST RESEARCH INST SAN ANTONIO TX ARMY
7FUELS AND LUBRICANTS RESEARCH LAB D M HANN ET AL. 1982
UNCLASSIFIED RFLRL-164 DAAK78-82-C-BBBi F/G 21/4 M
I"
1.8
1111IL2EMHIII II. I il 0 12
MICROCOPY RESOLUTION TEST CHARTNATIONAL BUREAU OF STANDARDS-1963-A
S " q
V _ .. - :-.- . . .- .. . .. . . . . . . .... . . . .-.
4-13
MECHANISMS OF COMBUSTION OF
HYDROCARBON/ACOHOL FUEL BLENDS
K. Seshadri
ABSTRACT
An experimental and theoretical study concerning the mechanisms of
combustion of alternate fuels has been initiated. The fuels to be considered
are homogeneous solutions of alcohols in liquid hydrocarbon fuels. A
thin, steady, laminar diffusion-flame in a counterflow configuration will
be established in the laboratory above pools of heptane/toluene/methanol,
heptane/toluene/ethanol, heptane/toluene, heptane, toluene, methanol and
ethanol. The ratios of the concentration of heptane and toluene in the
solutions will be chosen to approximate the ratios of aliphatics to
aromatics in commercial fuels (e.g. gasoline, diesel and shale oil).
Concentration profiles for stable species in the gas phase above the burn-
ing fuel surface will be measured by use of gas sampling and gas chromato-graphic analysis. Temperature profiles in the gas phase and in the fuel
will be measured by use of thermocouples. Critical conditions of flame ex-
tinction will also be measured. Theoretical analysis will be based on an
asymptotic theory in the limit of a large ratio of the activation energy
to the thermal energy in the flame. The mechanisms of combustion of fuel
blends will be compared with its components. Results to be obtained include
(1) quantitative comparisons of the relative reactivities of the fuels, (2)
quantitative values for the overall activation energies and the overall
preexponential factors for the gas phase oxidation of the fuels and (4)
chemical kinetic mechanisms for fuel pyrolysis. We anticipate that this
study will aid development of alternate fuels obtained from nonpetroleum
sources for use in automotive engines.
4-14
METERED OXIDIZER AND INERT GAS' ENTRY
BAFFLE
SCREENS
FLAME __________ FUELFUEL LEVEL INDICATOR
WATER OUT
WATER JACKET FOR - IWATER JACKET FORCOOLING EXHAUST GASES COIGFE U
WATER IN-
WATER
SUCTIONOUEXHAUST SCALE
WATER IN FULEL IN FLIEL OVERFLOW DRAIN
- 4-15
CC
> _ d
*> 4A 0 4AC
044 =
40
00
00
CD0
4-16
CC
(D00>
CC
2>
IM)
'90
t3,M)
4-17
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ii I
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. I* .-- -r: .
________________________________________
4-18
or
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(No 38 V3dA.WVJ3iVV
4-19
n
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4-21
Acoustic Signature from Flames as a
Combustion Diagnostic Tool
Warren C. Strahie
School of Aerospace Engineering
Georgia Institute of Technology
Atlanta, GA 30332
Experiments and analysis are described on the problem of using
combustion noise output as a non-intrusive diagnostic of the combustionr
process in gas turbine combustors. The acoustic noise output is analytically
linked to the heat release rate fluctuation distribution in the combustor;
* consequently, appropriate listening to the noise can yield the heat release
rate distribution. The experiments use multiple microphones and cross
spectral densities between microphone pairs as the imput to the theory to
extract heat release rate. Verification is performed by ion density
measurements in the combustor. Speed of sound distribution, which is
needed in the theory, is also measured by an acoustic technique. Prior work
on an open jet flame is also discussed.
4-22
FLAME BRUSH
BURNERMICROPHONES
ANECHOIC/ CHAMBER
I
POWER B lkK 2604
SSUPPLIE.S AMLIFIE.a .
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4-23
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0 0.5 110DISTANCE FROM BURNER PORT
FLAME LENGTH
Heat release fluctuation function andlight emission function vs. length -along flame axis for the *-0.8 :f lame at 300 Hz.
V 4-24
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4-31
COMBUSTION AND MICRO-EXPLOSION OF WATER/OIL
EMULS IONS IN HIGH-PRESSURE ENVIRONMENTS
C. K. Law
Northwestern University
Water/Oil (W/O) emulsions hold potential for soot reduction, multi-fuel
capability, and self-extinguishment upon spillage and incendiary ignition.
The present program aims to study the combustion characteristics of W/O emul-
sion droplets in general, and their behavior in high-pressure environments in
particular. Of special interest is the exploration of an explosive droplet
combustion phenomenon termed micro-explosion, which may be responsible for
much of the potential benefits of emulsion utilization.
The experiment involves injecting a stream of equally-spaced and mono-
:'.oerse droplets into a co-flowing hot oxidizing gaseous stream. The drop-
lets subsequently ignite and burn. Their combustion behavior are studied via
direct photography and sampling. W/O emulsions, alcohol/oil solutions, and
miscible fuel blends have been studied.
For the reference case of pure component droplets, we have observed
significant temporal variations of the flame-front standoff ratio in accord-
ance with our previously postulated concept of fuel vapor accumulation in the
* inner region to the flame. Flame extinction also spans a substantial period
* contrary to the assumption of gas-phase quasi-steadiness.
For two-component fuels with sufficiently different volatilities, a flame]
* shrinkage phenomenon was observed indicating the occurrence of significant
droplet heating as the droplet composition becomes more concentrated with the
4-32
less volatile, higher-boiling-point, components. Severe situations of shrink-
age can even lejd to droplet extinction.
For three-component fuels consisting of a surfactant, two flame shrink-
ages occur. Micro-explosion usually take places at the end of the second
shrinkage when the droplet becomes highly concentrated with the surfactant.
Preliminary results for pressures up to 5 atmospheres seem to indicate
that the occurrence of micro-explosion is enhanced with increasing pressure,
although more detailed studies are needed.
Increasing water content up to 30% by volume intensifies micro-explosion.
By changing from our macro-emulsions to the Army's micro-emulsion, the explo-
sion intensity is somewhat weakened and the explosion frequently occurs in two
stages.
.07-
4-33
COM5USTION A14D UTILIZATION o W/0 EmU/SiOS
-ARMYS INTERESTS•
I. Flow- RASISTMT FURL
2. COMBUSTION CHARACTERISTICS IN ENfINES
*"EN&INE TOMTI* RESUL.TS:
_|. REUCTION IN SooT mt, NO ,
2. INCREASED CO AN HC EMISSIoNs
3. EFFECTS ON FUEL EcoNoMY INCONCLUSIVE*6l
U;
UI
*!
~. . . . . . . . . .
4-34
OBTECTIVIRS OF Pgru&ow PRo*rAHj
o UNDERPSTAND nil coMBUsTIoN MIeCHANISM&
OF SIN*I* DRWOPLATS OF WIO 9MUL41619 AkNDMULTICOMPOI*NT FUR.L B&L&Nbs.
*TO FURNISH INFORMATSON4 ON OpTIfMIZATION OF
FUEL FORMULATION FOR FIRE WESISrENCY AND~ENGINE combusTION.
*EmPfHAS ES:
1BASIC GrASIFiCATION 5OEGANIeS2.Memo- ErPLOSIOW
3. HIGH PRESSURE EFFECTS4. ALCOHOL bLENDIN*
5SOOT FORMATIOW.
4-35
&ERoIMENTAL Mir-ToDOLO*Vy
SPECIFICATIONS OF COMIUSTION CHNAMBER:
CONTINUOUS Loii-SPEct P~owMAXIMUM PRESSURE :20 ATMMAximum Temp. :1000 *K
VARIABLE OXV*rEN COCURTO
HOT COMBUSTION ENVIRON MENT PRODUCEID
7THRou~rH EmathER PEisTIvF HEATiNert ORAsCOMBsusTIowNo RfUt oM FlAT FI.AMS BURNeR.
*DtoPi.ET PROwUCE By tNec ltEr PRMINoTieciNIQUE : oo.*U <do < .9OO)am .VARlAsI..
-SpoiCI* ,Re <(I
*QUANTITATIVE DATA ACQUIRED THROMM~DIRECT PROOWRApHY 4 SPIMPUt~dr.
4-36
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5-1
Session 5FUELS/ENGINES TECHNOLOGY
Chairman: F. W. SchaekelU. S. Army Mobility Equipment Research and Development Command
Fort Belvoir, VA4 p'
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iw
S
5-3
HOW GUM AND DEPOSITS FORM IN HYDROCARBON FUELS
by
Frank R. Mayo and Bosco Y. LanSRI INTERNATIONAL
The object of this research is to determine how and why soluble gum and
deposits appear in jet turbine and diesel fuels and thus how to predict and
prevent their formation. Oxidations were carried out in air at 130*C. To
focus attention on inherent stabilities of fuels and to avoid effects of
previous storage, all fuels were distilled in vacuum before use and stored
under nitrogen at -12*C. Oxidation is required for gum or deposit formation.
The hydroperoxides formed cause step-wise coupling of fuel molecules to
heavier products. Whether these remain in solution depends on the solvent
properties of the fuels. Since our work was reported to the Division of
Fuel Chemistry at the March 1982 ACS Meeting, experiments with dodecane and
a jet turbine fuel have shown how small proportions of indene or N-methyl-
pyrrole greatly increase rates of gum formation (and are thereby soon
exhausted), with either an increase or a decrease in the rate of oxygen
absorption.
The major remaining problems are the effect of oxygen concentration on
gum formation, determination of which fuel components lead to stability andinstability, and the relative importance of gum formed on storage and by
very rapid oxidation and condensation in hot engine zones.
I
5-4HOW GUM AND DEPOSITS FOR' IN HYDROCARBON .UELS
Frank R. Mayo and Bosco Y. Lan, SRI International
Object: To determine how and why soluble gum and
deposits appear in jet turbine and diesel fuels, and
thus how to predict and prevent their formation.
SLTUARY 0 PREVIOU7S WORK AT SRI INTERNATIONAL
Rates of oxidntion and gum formation (new method)were 7nersured in cir at 1300C.
Gum is foxned by sterwise condensetion of oxida-tion products of fuel by hydroperoxides.
Whether gum formation leads to deposit formationdepends on the solvent properties of the fuel.
Pmong different fuels, there is no correlationbetween deposit formation and rate of oxidation.
In different oxidations of the same fuel, gumformation is proportional to rate of oxidation.
RATE OF OXIDATION (M/hI
lu 0
C0
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-o=0 "
,m
2nC
~1 5-5OXYGEN ABSORBED 1-ro 11 ~
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50
40 2 0 1
(NMPI IM)
FIGURE INITIAL. RATE OF OXIDATION OF FUEL A AND O.O0BC^NE WITH IWIF AT 1300
OXYGEN ABSORBED lpmIoIB/ INuI)
so U
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- 5-6
OXYGEN ABSORBED &umole/g fuel)
8.-mVo.
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90;-
CONCLUSIONS
Gum and deposits are closely associatedwith oxidation of fuel.
Gum r-nd deposits incorporate the fuel componentsthat are most susceptible to oxidation andPre consumed rapidly.
The reactive components usually increase gum forma-tion, but they may increase cr decrease the rateof oxygen absorption, depending on their propor-tions in the fuel.
SOI:E RMAINING PROBL.IAS
W ;hat con ponents most affect fuel stability?
WhPt is the effect of oxygen pressure ongut and deposit formation?
Do derosit3 on hot engine parts come mostly Ifrom u-2 formed in storage or from.sudden oxidetion near the hot metpl? 4
How applicoble ere our results and con-clusions at 1300C to service conditions?
Do soluble 'ietnls end rmetpl surfaces playimportant parts in gum and deposit formation?
'r
-
. -::"..: ,• ..
...
AFLRL Basic Research on Fuel Storage StabilityG. H. Lee
L. L. StavinohaU. S. Army Fuels and Lubricants Research Laboratory
Southwest Research InstituteSan Antonio, TX
ABSTRACT
This program was started as a 3-year study under 6.1 funding by USAMERADCOM inOctober 1981. Its major objective is to determine the primary chemical reactionmechanisms causing "insoluble" particulate matter and adherent gums to form inneat and additive-treated middle distillate fuels. Reaction kinetics and variationsin chemical composition of the degradation products are being determined throughaccelerated aging at 650, 800, and 950C in both large (30-gallon) and small (200 cc)containers. The weight of "insoluble" particulate matter per liter of fuel isdetermined as a function of time using ASTM D 2276 techniques. The rate ofparticle growth will be determined using instrumentation capable of measuring in
. the 0.5- to 90-11m range.
Characterization of the chemical functionalities constituting the particulates andgums is being studied, following chromatographic separation, by infrared
,. spectrophotometry, mass spectrometry, nuclear magnetic resonance, and othertechniques as appropriate.
5
D5-7
AFLRL DISTILLATEFUEL-RELATED ACTIVITIES
BASIC RESEARCH -___ *MECHANISM OF DEGRADATION AND ADPITI VE INHIBTON*FUEL CONTAINER/FUEL STABI~LY INVLVEMENT
TEST TECHNIQUE e FIELD TEST QUALMTYDEVELOPMENT TECHNIQUES I* PREDICT FUTURE QUALITY
o LABORATORY TEST I QUALITY, PREDICTIONTECHNIQUES *--- -. • FUEL STEM DEBRIS
IDENTIFCATION, WORLD WIDE FUEL • INJECTOR FOUUNGQUAL"I Y ASSESSMENT BENCH TEST
LABORATORY * SPECIFICATIONS,SURVEY FUEL.S REFINERY - METHODS FIELD MANUALS, ]
* 'r-FERENCE/REFEREE FUEL CORRELATION ETCi.>: | / DEFINITON
BETC TEST TECHNIQUE *__ SURVEY AND TECHNIQUE OPTIMIZATION (COMPLETED)
! DEVELOPMENT o SYNTHETIC FUEL STABILITYDEOMT SOURCE OF FUEL STABILTY INFORMATION & TESTING
-... DOE, SPRO, CRUDE AND -eSTATE OF THE ART REVIEW (COMPLETED)* PRODUCT STORAGE * QUALITY ASSESSMENT (COMPL.D)
AS'ITM 0-2. E-V a• SYMPOSIUM (STP751 (COMPLETED)STABIU AND o METHODS DEVELOPMENT:. .CLEANUNFSS le APPENDICES TO SPECIFICATIONS .
I * YUMAA PG TEST (U)MITIED) AND POMCUS TEST (COMPLETED)ADTVSR MARINE CORP. NTPS TESTADDITIVES FOR LETTERKENNY ARMY DEPOT (PROPOSED), DEPOT USE DOD-S STABILIZER ADDITIVE SPEC.
~ VOLATILE CORROSION INHIBITORS FOR FUELS/FUEL TANKS IN VEHICLE (PROPOSED)
" I*FORT HOOD* FORT RILEY
FIELD PROBLEM ----- * PATRIOT MISSILE (WHITE SANDS) pSURVEILLANCE " FORT POLKI ARY DEPOTS, ETC.
VHLFE*SAE J-905 TEST RIG DEFINITIONVEHICLE FUEL FIELD UMTNG VALUES (PROPOSED)FILTER LABORATORY-FIELD CORRELATION (PROPOSED)
* ASTM COMMITTEE D-2* MAINTENANCE COUNCIL OF AMERICAN
PUBLC/TECHNICAL TRUCKING ASSOCIATIONRELATIONS e DARCOM CORROSION GROUP
* CONFERENCESo DTIC PUBUCATIONS
5-8
5-9
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71
5-10
OBJECTIVE:TO INVESTIGATE THE MECHANISMOF MIDDLE DISTILLATE FUELDETERIORATION THROUGH CHEMICALCHARACTERIZATION OF THEMATERIALS INVOLVED AFTERAPPLICATION OF VARIOUSACCELERATED AGING TECHNIQUES
0V
5-11
APPROACH:
1. REVIEW AND ASSEMBLEPERTAINENT LITERATURE ARTICLES.
2. SELECT APPROPRIATE TEST FUELS.3. AGE THE CHOSEN TEST FUELS
(WITH AND WITHOUT ADDITIVES)USING PROVEN METHODS.
4. COLLECT AND CHEMICALLY ANALYZE"SOLUBLE" AND "INSOLUBLE"DEGRADATION PRODUCTS.
5. FROM THE CHEMICAL STRUCTURES(CLASSES) DETERMINED, FORMULATEVIABLE DETERIORATION MECHANISMSAND COMPARE TO THOSE SUGGESTEDIN LITERATURE.
S
V
. "-V
5-12
PLANS FOR DEVELOPMENT
OF AH51FG (3)
BEGIN FY82 LITERATURE SURV'EYSELECTION OF STUDY FUELS
65'C-s80C-95"C VEHICLE STORGE
NEAT FUEL ADDITIVE TREATED DETERMINATION AND PROBLEM AREAS IDENTIFIEDAPPUJCATION OF APPROPRIATE UNDER OTHER ON-GOING
ANALYTICAL TECHNIQUES PORM
* RATE OF M FORMATION
IOF MTERI COSIINRAL
PARTICLE~ORR GRONT OUDDEEACOF ~~ IETC DERDARNORDUTGSLCTDCOPNET
ONCE ~ ~ ~ ~~BEI DEYTAVEFRMDMOIENRMNETION~mS
MATEIALENTAIND O LAORAOF VERIFYA POSMUAITONS
OFND FELRDATOLTERODICPTSIONTE OPOETOFC SAEY KAOS FILTRMTET RIG)EMNSMLRIIS
ESTABLISH ACTUAL MECHANISMSOF GUM FORMATION
END FY 84
FINDINGS
1. Solubility of filterable particulates changes with time after filtration.
2. Benzene solubles appear to have ester character.
3. Pyridine solubles are probably nitrogen containing,non-ester compounds.
4. The major products appear to be salts such as sulfatesor sulfonates even though GPC appears to indicate MW'sof up to approximately 1500.
5. Adherent gum formation does not occur Qn "large" scale aging)until after insoluble particulates form. This is not necessarilytrue in small scale aging.
6. The sum of adherent gum weight and insoluble particulate weightappears to increase at the same rate as the insoluble particulatesprior to adherent gum formation (large scale).
7. Degradation products appear to be very similar thus beingindependent of the source or additive.
I1
5-12A
-. . .-~_- 1
5-13
BASIC RESEARCH ON FIRE-RESISTANT DIESEL FUELW. D. Weatherford, Jr.
D. W. NaegeliU. S. Army Fuels and Lubricants Research Laboratory
Southwest Research InstituteSan Antonio, Texas
ABSTRACT
Measurements of flammability limits of diesel fuel vapors in air diluted with variousamounts of water vapor have established that such mixtures containing more thanabout 24 vol% water vapor cannot burn.
Vapor pressure measurements confirmed that FRF systems containing 10 vol% waterare blanketed by equilibrium vapors containing at least 24 vol% water for liquidtemperatures greater than about 70 0 C. Moreover, the same ratio of surfactant towater yields the same equilibrium vapor water content with FRF containing eithermore or less than 10 percent water.
Vapor pressure measurements indicate that FRF blends containing 6 vol% surfactantand between about 2 and 10 vol% water are true microemulsions which exertequilibrium water partial pressures significantly less than that of pure water. Whenthe water content is less than about 1 vol%, these systems appear to be micellarsolutions with even lower equilibrium water partial pressures.
The flash points of DF-2-type FRF blends containing 10 vol% water were about thesame as those of the neat fuel when the flash point was less than about 70 0 C. Whenthe flash point of the base fuel exceeded 700C, a flash point for the FRF was notdetectable. For these FRF blends at temperatures above 700C, the partial vaporpressure of water is higher than the 24-percent vapor phase composition limit forflammability.
Horizontal flame channel experiments indicate that the lowest water content whichprevents vapor burning in dynamic (i.e., nonequilibrium) situations is between 0.5and 5 vol% in the liquid.
A special apparatus was developed to measure liquid-surface evaporative coolingand liquid-surface-flow heating effects in the vicinity of a simulated flame on theFRF surface. The results confirmed that evaporative cooling effects are signifi-cant, but that they are not responsible for the self-extinquishing properties of FRF.In fact, the data indicate that the surface-flow effects in front of the simulatedflame (Marangoni effect) provide sufficient surface heating to generate the greaterthan 24 vol% water vapor composition needed for self-extinguishment even whenthe bulk liquid FRF is much cooler than 70 0 C.
*
5-4
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5-25
SYNOPSES OF RELATED BASIC RESEARCH AT SwRI
T.W. Ryan, IIIDepartment of Fuels and Lubrication Technology
Southwest Research InstituteSan Antonio, Texas
ABSTRACT
Four areas of basic research which are currently being addressed within theEnergy Systems Research Division of SwRI are:
* injection and atomization in diesel engines;* combustion of fuels in diesel engines;
0 spray and evaporation of fuels in turbine engines;0 injection and atomization of two-phase fuels.
o Work in these areas require extensive facilities, including various specialized engines,bombs and flow devices, as well as state-of-the-art diagnostic systems including the
* latest in laser and real-time computer technology.
* . Four different SwRI projects, one in each of the areas listed above, are describedbriefly. The emphasis in most cases is placed on a description of the facilities beingused in the particular project. Examples of the experimental results from each projectare presented.
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LILLU a-
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ILWB zo!~ 2 c
00
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w UUU 0
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5-49
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5-50
COMPARISON OF FUEL INJECTION BETWEENNEAT DIESEL AND 20% MOGUL L SLURRY, 174 PSIG, 80°F
(50 to 600psec)BASE FUEL
NEAT DIESEL TIME, isec 20% MOGUL L SLURRY
50
100
150
200
250
300I
350
400
450
500
550
6001
"...-'..-'-,.:.... .,.- ... . . . " .. . ... ". . .. ..--.-. *. -. . . -
5-51
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IL U j. L. LL,
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INC-
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A6-1
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Session 6DISCUSSION GROUPS
on* Reciprocating Engines/Fuels
Leader: S. S. LestzPenn State UniversityUniversity Park, PA
* Turbine Engines/FuelsLeader: A. M. MellorDrexel UnivesityPhiladelphia, PA
;iI
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