Embed Size (px)
Citation preview
UNIVERSITY OF NAPLES FEDERICO IIDepartment of Industrial Engineering – Aerospace Division
TERMOGRAFIA ALL’INFRAROSSO NELL’AEROSPAZIO
(An Excursus on Some Research Performed with Infrared Thermography at Federico II)
Giovanni Maria CarlomagnoUniversitàUniversitàUniversitàUniversità di Napoli di Napoli di Napoli di Napoli Federico II Federico II Federico II Federico II –––– DIIDIIDIIDII
AIAN ConferenceMay 30, 2018Naples, Italy
RESEARCH TEAM Theresearch teaminvolved in the present work was, over time,primarily composed by:
o Tommaso Astaritao Piergiorgio Berardio Simone Boccardio Gennaro Cardoneo Giovanni Maria Carlomagnoo Stefano Discettio Luigi de Lucao Mauro Galloo Carlo Salvatore Grecoo Andrea Ianiroo Michele Imbrialeo Carosena Meola+ Several Master and PhD students
(who,really, performed most of the experiments)
SCOPE OF THE PRESENTATIONThis presentation reviews some of the experimental and theoretical work carried out, overthe past several years, by the research team the peaker belongs, while employing infraredthermographyin thermo-fluid-dynamicsandNDT for someAerospace applications.Most of the work was performed atUniversity of NaplesFederico II and together with:
Centre d’études aérodynamiques et thermiques(CEAT), Poitiers, FranceCentro Spazio(Space Centre), Pisa, ItalyDelft Technical University, Delft, The Netherlands (prof. Scarano group)Italian Centre for Aerospace Research(CIRA), Capua, ItalyPolitecnico di Torino, Torino, ItalyTokyo University of Agriculture and Technology, Tokyo, JapanUniversidad Carlos III de Madrid , Madrid, SpainUniversità di Pisa, Pisa, ItalyUniversity of Tokyo, Tokyo, JapanPurdue University, West Lafayette, IN, USA
Among others, someextended courseswere given: Lecture Series, Von Karman Institute for Fluid Dynamics,Rhode-St. Genese, Belgium, 1990,
1993 Quantitative Infrared Thermography Courses, aroundEurope andCanada, 1994, 1996,1998,
2000, 2002, 2004, 2006, 2008, 2010, 2012, 2014, 2016 UIT Summer course on “Thermofluiddynamics” for PhD students,Siena, 2003, 2010 Lecture Series on “IR Thermography Principles and Applications”at the University of
Sharjah, UAE,,Sharjah, UAE, 2008 Lecture Series on “Modern research methods in convective heat transfer” at Ural Federal
University Boris Yeltsin,Ekaterinburg , Russia, September 23/25, 2014
Termogramma dello Space Shuttle al rientro (NASA).
All’epoca (early 1980’s), risoluzione spaziale molto bassa.
0.85 kg1970’sNowadays
Handheld
HOW IR CAMERA CHANGED OVER TIME
21,000,000 Lit → ~180,000 €~500 €
(Leeward side)
(1990’s)(early 1980’s)
OUR STARTINGAt the beginning of the70ties, whenwe were first involved with infraredthermography, our research groupstarted withnon-destructive testing.
This are two isothermal lines in asteel slab with a longitudinalcylindical cavity which, initially atambient temperature, wassuddendlyexposed to steamon one side, whileviewed fromthe other one.
Carlomagno GM e Berardi PG,Trasmissione del calore in regime instazionario attraverso lastrepiane con cavità interne, Atti XXIX Cong. Naz. ATI, Florence, Italy, Vol. 1, pp 87-98,1974
CAVITY
AGA THERMOVISION 661
AGA THERMOVISION 661
We started to use the concept of TIME DEPENDENT THERMOGRAPHY
from the Abstract:
The present research was focused on the study of unsteady surface temperature fields to obtain information about the internal physical structure of a thermally loaded system, by discriminating among surface temperature differences
and their time evolution;
in other words, the idea was to adopt the time variablein the place of the depth variable(i.e. the coordinate normal to the observed surface) to recover knowledge about the
“ inside” of the system. (inverse problem)
Quite certainly, this paper introduced the lock-in concept
because we firstly mentioned the specimen harmonic heating.
Unsteady thermotopography in non-destructive testingGiovanni Maria Carlomagno, Pier Giorgio Berardi
Proc. 3rd Biannual Exchange, St. Louis,MO, USA (IRIE ‘76 )Pages 33-40, Available on Research Gate
NON-DESTRUCTIVE TESTING ( Lock-in)
For phase images, the thermal penetration depth is: p = 1.8 µ
Direct estimation of defect depth
f ππππαααα
µµµµ =Thermal diffusivity
Heating frequencyHeat diffusion lenght
Lock-in thermography setup
• a periodic heat flux impinges onthe surface of a sample,
• IR camera monitors the evolutionof sample surface temperature,so as to look for local differencesof phase, and/or ofamplitude, ofthe signal.
s
Defect
Carlomagno GM and Berardi PG, Unsteady Thermotopographyin Non-Destructive Testing, inWarren C ed., Proc. III Infrared Information Exchange, 33-40, St. Louis, MO. USA (1976)
Materials
Composite materials: Carbon Fibre Reinforced Polymer (CFRP), Glass Fibre Reinforced Polymer (GFRP)
Hybrid composites: Fibre Metal Laminates FML (i.e., GLARE®)
Sandwiches CFRP/Nomex® with CFRP skins and Nomexhoneycomb core
Plastics
Metallic alloys (such as for turbine blades)
Masonry structures
Problems
Backing film inclusions in composites
Impact damage in: CFRP, GFRP, GLARE®, Sandwiches
Polyethylene deterioration due to incorrect cross-linking
Fibres misalignement
Residual ceramic in turbine blades
Detection of moisture in sandwich structures
Frescos or mosaics detachments in masonry structures
p = 3mm
The smaller defect of D = 2 mm is missed
p = 1mm
All defects are visible
Glass Fibre Reinforced Polymer GFRP with slag inclusions
Specimens include twosound GFRP layers within between them a thinTeflon insert ofdiameter
D = 2, 3, 4, 6, 8mm
and located atdifferentdepth p
Tests performed with Lock-in thermography and the ThermaCamSC3000
Teflon insert side
19.0 mm12.7 mm6.35 mm
Thickness 0.2 mm
S (mm) 7 6.3 5.6 5.1 4.5 4 3.5 2.6 2.2
Step wedged CFRP with slag inclusions very thin Teflon inserts to simulate inclusions of backing film
Lock-in thermography with ThermaCamSC3000
It is possible, by close-up views, to better visualize
deeper defects and the junction between two stepsAs well as to better outline a defect
DETECTION OF RESIDUAL CERAMIC in serpentine cooling passages of turbine HT blades
Blade surface viewedby the camera
Rotor bladeInternal core (passages for blade cooling)
Meola C, Carlomagno GM, Di Foggia M and Natale O, Infrared Thermography to Detect ResidualCeramic in Gas Turbine Blades,Applied Physics A – Material Science and Processing, 91, 685-691 (2008)
Rotor blade inspection(Lock-in)Phase images for f = 0.65 Hz
Phase
-0.075
-0.011
0.053
0.117
0.181
0.244
0.308
0.436
Phase
-0.430
-0.378
-0.326
-0.274
-0.222
-0.169
-0.117
-0.013
Thephase angle discontinuities(inside the white rectangles)in the first channel fromthe trailing edge (right side) testifythepresence of residual ceramicto be removed.
A04 A13
Meola C, Carlomagno GM, Di Foggia M and Natale O, Infrared Thermography to Detect ResidualCeramic in Gas Turbine Blades,Applied Physics A – Material Science and Processing, 91, 685-691 (2008)
Phase
-0.386
-0.339
-0.292
-0.246
-0.199
-0.152
-0.105
-0.011
residual ceramic
Stator blade inspection(Lock-in) Serpentine cooling passages
Meola C, Carlomagno GM, Di Foggia M and Natale O, Infrared Thermography to Detect ResidualCeramic in Gas Turbine Blades,Applied Physics A – Material Science and Processing, 91, 685-691 (2008)
(Thermographic On-line monitoring and
Non-destructive testing after impact)
We were also interested in
IMPACT EVENTS IN COMPOSITES
Meola C and Carlomagno GM, Infrared thermography to impact-driven thermal effects,Applied Physics A,96, 759-762 (2009).
Meola C and Carlomagno GM, Impact damage in GFRP: new insights with Infrared Thermography,Composites Part A, 41, 1839-1847 (2010)
Meola C, Carlomagno GM, Ricci F, Lopresto V, Caprino G, Investigation of Impact Damage in Compositeswith Infrared Thermography, 6th NDT in Progress, Prague (Czech Republic), Ed. P. Mazal, pp. 175-182(2011)
IMPACT WITH CHARPY PENDULUM
Infrared camera
Specimen
Hammer
Front view Side view
Thermographic images are acquired in a fast time sequence
∆T = T(i,j,t) – T(i,j,0)
The first image T(i, j, t =0) of the sequence (i.e. the ambienttemperature of the specimen surface, before the impact) issubtractedto each subsequent image so as to generate mapsof temperature differences∆T caused by the impact:
DATA ANALYSIS
where: i and j represent lines and columns of the surfacetemperature matrix, respectively.
Therefore, a newsequence of∆∆∆∆T images is produced.
Samples ofGFRP, CFRP andGlare® are tested.
at 300Hz images are composed of 48 lines
HIGH SPEED ACQUISITION OF THERMAL IMAGES GFRPwith FLIR SC3000
at 900Hz images are composed of 16 lines
SEQUENCE OF ∆∆∆∆ΤΤΤΤ IMAGES GFRP, Ei = 19J, taken at300Hz with SC3000
Before impact
t = 0.0033s
t = 0.01s
t = 0.02s
t = 0.40s
t = 0.90s
dC
-2
0
2
1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81
nimg
t = 0.001 s
t = 0.009 s ∆T
TIME EVOLUTION OF ∆T IN A POINT BESIDES THE IMPACT ZONE
GFRP, Ei = 12J, SC3000 at900Hz
Thermo-elastic effect (cooling down)Thermo-plastic effect (heating up)
Meola C and Carlomagno GM, Infrared thermography to impact-driven thermal effects, Applied Physics A, vol. 96, pp. 759-762 (2009).
∆
Initial temperature
Lock-in phaseimage f = 0.14Hzafter impactto detect defects
Raw thermal image takenduring the impact
Fotograph in the visibleof a translucent GFRP, after impact
19 mm
DAMAGED AREA IN GFRP
ACQUISITION WITH THE SC6000 AT 96 Hz∆T image sequence during impact on CFRPat 2.8J
-1.5
1.5
t = 0s
t = 0.001s
t = 0.003s
t = 0.006s
t = 0.007s
t = 0.009s
t = 0.016s
t = 0.020s
t = 0.026s
t = 0.058s
t = 0.171s
t = 0.377s
SEQUENCE OF ∆Τ∆Τ∆Τ∆Τ IMAGES OF GLARE ®
taken with SC3000 at 900Hz, specimen impacted at 2.7J
Meola C, Carlomagno GM, Ricci F, Lopresto V, Caprino G, Investigation of Impact Damage in Compositeswith Infrared Thermography, 6th NDT in Progress, Prague (Czech Republic), Ed. P. Mazal, pp. 175-182 (2011)
°C
Times are much shorterthan before because of higher average thermal diffusivity
Aluminium
GFRP
GLARE®
Appearedon 2017
Much of our work isreported in this book
But, in the 80s, we were forced to mainly switch to:
THERMO -FLUID -DYNAMICS(that was our most proper business)
In fact, the group was affiliated with the Gasdynamics Institute
INFRARED THERMOGRAPHY IN THERMOINFRARED THERMOGRAPHY IN THERMOINFRARED THERMOGRAPHY IN THERMOINFRARED THERMOGRAPHY IN THERMO----FLUIDFLUIDFLUIDFLUID----DYNAMICSDYNAMICSDYNAMICSDYNAMICS
Series: EXPERIMENTAL FLUID MECHANICS Series: EXPERIMENTAL FLUID MECHANICS Series: EXPERIMENTAL FLUID MECHANICS Series: EXPERIMENTAL FLUID MECHANICS - Springer
Tommaso Astarita and Giovanni Maria Carlomagno2013 - 248 p. 119 illus., 47 in color
ISBN 978-3-642-29507-2
ISBN 978-3-642-29508-9 (eBook)
APPLIED & TECHNICAL PHYSICS , MECHANICS
ABOUT THIS BOOKABOUT THIS BOOKABOUT THIS BOOKABOUT THIS BOOK
Information• Introduction into this very accurate surface temper ature measurement method • Examines a significant number of examples and appli cations in detail • Guides both, the experienced researcher and the you ng student
Infrared thermography is a measurement technique that enab les to obtain non Intrusive measurements ofsurface temperatures. One of the interesting features of th is technique is its ability to measure a full twodimensional map of an object surface temperature and, for th is reason, it has been widely used as asurface flow visualization technique. Since the temperatur e measurements can be extremely accurate, it ispossible, by using a heat flux sensor, also to measure convec tive heat transfer coefficient distributions ona surface, making the technique de facto quantitative. This book, starting from the basic theory of r adiationand heat flux sensors, guides, both the experienced researc her and the young student, in the correctapplication of this powerful technique to study convective heat transfer problems. A significant number ofexamples and applications are also examined in detail, ofte n pointing out some relevant aspects.
Table of contents:
Introduction and Historical Groundings - Physical Backgro und - Infrared Scanner - Heat FluxSensors - Restoration of Thermal Images - Some Practical Con siderations - Applications.
MEASUREMENTS OF HEAT FLUXESMeasuring heat fluxesfrom a streamto a surface is one of themain and difficult issues ofthermo-fluid-dynamics.Measuring heat fluxes involves measuring temperatures.
The use of an infraredcamera astemperaturedetector is favourablewhen compared tostandard detectors.
• Entirely two-dimensional detector(allows the evaluation ofheat fluxvariations and/or of errors due totangential conduction within thesensor).
• Non-intrusive detector (avoids errorsas those due tothermal conductionthrough thermocouples, or RTD’s,wires).
The temperature has to be measured inheat flux sensors(generally slabs) by means oftemperature detectors.
The appropriate equation for heat conduction in solids, appliedto the selected sensor model, yields the relationship by whichthe measured temperatureis correlated to theheat transferrate.
THIN SKIN - The thin skin is based on the assumption that athin slab constituting the sensor behaves as anideal calorimeterwhich is isothermal across its thickness.Heat flux uniformly increases the slab temperature with time.
THIN FILM - The thin film is based on thetheory of heatconduction in a semi-infinite wall.Heat flux steadily increases the slabsurfacetemperatureT(t,0).
y
T
y
T(t,y)Ti
Ti(0)
adiabatic
infinite
T(t)Flow
Flow
UNSTEADY HEAT FLUX SENSORS
kc
tQT - T(t,0) w
i 2
πρ
=
sdt
dTcsQw
ρ=
hs/λ 1
CARLOMAGNO GM, Heat Transfer to Linear Bodies in Two-Dimensional Hypersonic LowDensity Flow,Proc. XXth Int. Astronautical Congress, 481-488, Mar del Plata, Argentina (1969)
Qw = Qc - Qr
Qw = const
h T( w-Taw)
s
V
kq& kq&
rq&
rq&
cq&
jq&
HEATED THIN FOIL (STEADY)
aww
ckrj
TT
qqqqh
−−−−
=&&&&
• is theknown Joule heating• are the losses due to radiation• are due to tangential conduction• is convection at sensor back side• h(Tw - Taw) is the convective fluxto
be measured
jq&rq&kq&
y
Tw
Taw ,
flowing streamIf the Biot number is:
Bi = hs/λ << 1
the heated foil can be assumedisothermal across thicknessand measurements may beperformed on either foil side.
The heat transfer coefficienthis inferred from the energyconservation equation:
cq&
It consists ofheating by Joule effect a thin metallic foil(e.g. AISI, 40µmthick), or a printed circuit board, and (by measuring the foil temperature)computing the heat transfer coefficienth between the foil and the stream.
zheated foil
infrared camera
traversing system
manometer
thermometer
plenum chamber
hea exchanger
air supply
needle valve
EXPERIMENTAL ARRANGEMENT FOR IMPINGING JETS (1986)The heated foil consists of about 40µµµµm thick, either AISI 304, or constantan, foil
IMPINGING JETS ( heated thin foil)
heat exchangernozzleof diameterd
Jet impinging on a plate, contours of constant temperature; z/d = 6, Re = 28,000 (1986)To my knowledge, this should be the first thermographic image of an impinging jet
Agema 782100x100 px
Nu
63
1
02
1
41
-4 -2 0 4
y/D
4 2
0
-4x/D
RELIEF MAP OF THE NUSSELT NUMBER OF A JET IMPINGING ON A FLAT PLATE FOR D =10mm, z/d = 2AND ReD = 28,000 (1990)
In a 1990 technical meeting in Kozubnik (Bielsko-Biaɫa, prof. Fisdom), aparticipant asked if these results originated from numerical computations !
NUSSELT NUMBER
k
hDNu =
)( awwc - TThq =&
Agema 782100x100 px
HYPERSONIC FLOW(e.g., heat transfer in re-entry problems; thin film )
De Luca L, Cardone G and Carlomagno GM: Image Restoration in Thermo-fluid-dynamic ApplicationsofIR Digital Imagery, in Lettington A.H. ed., Infrared Technology and Application, SPIE Vol.1320, 448-457,ISBN 9780819403810 (1990)
De Luca L, Cardone G, Carlomagno GM, De La Chevalerie DA and De Roquefort TA , Flowvisualization and heat transfer measurement in a hypersonic wind tunnel, Exp. Heat Transf., Vol. 5, pp. 65-78. (1992)
Cardone G, IR Heat Transfer Measurements in Hypersonic Plasma Flows,QIRT Journal, 4, 233-251 (2007)
The model is suddenly exposed to a high enthalpy hypersonic stream atM = 8.15,To = 800K, αααα = 30° (CEAT, Poitiers) and thermal images of thewindward (bottom) side are recorded as a function of time.(1990)
Several (9) small cylindrical wires (0.5mm high, 0.22mm in diameter andplaced at 5mmsteps) are implanted 30mmaway from the ellipsoid nose.
Flow
M = 8.15 To = 800K
α
(It resembles the Shuttle forepart –thin film )
Temperature map of thewindward sideof a double ellipsoid modelat M = 8.15, To =800K, αααα = 30°, 0.48safter model injection.
Wires wakesare clearly visible withturbulization and subsequentrelaminarization,except for the two central ones which turbulize again.
De Luca L, Cardone G, Carlomagno GM, De La Chevalerie DA and De Roquefort TA , Flowvisualization and heat transfer measurement in a hypersonic wind tunnel, Exp. Heat Transf., Vol. 5,pp. 65-78. (1992)
Flow from left to right
Agema 782100x100 px
FLAT PLATE FOLLOWED BY A RAMP(hypersonic flow with control surfaces; thin film )
Cardone G, IR Heat Transfer Measurements in Hypersonic Plasma Flows, QIRT Journal, 4, 233-251 (2007)
HEAT FACILITYHigh EnthalpyArc-heatedTunnel, Centro Spazio (PISA), Italy
Main characteristics are:
• Blow-down tunnel
• Test duration: 20 - 300ms
• Mach number: 6
• Total Temperature: 300 - 4000K
• Total Entalpy: 0.3 - 6MJ/kg
• Reynolds Number: 104--106/m
• Fluids: air, helium, argon, CO2
FLAT PLATE WITH 15 ° RAMP IN A M = 6 HYPERSONIC FLOW
Leading edge Hinge line
FLAT PLATE WITH 15° RAMP
; Ho= 2.23MJ/kg ; Po= 4.56bar
Leadingedge
Flow from
left to right
Hingeline
0 40 80 120x
0.001
0.01
MO
DIF
IED
ST
AN
TO
N N
UM
BE
R(b
ase
d o
n H
o)
TEST# 08-014FP teory # 08-014TEST# 08-0017TEST #09-002FP teory # 09-002CIRA
Condizioni NominaliHo=1.8 [MJ/Kg]; Po=6 [bar]
x [mm]
CIRA CFD
FLAT PLATE WITH 15° RAMP Nominal conditionsHo = 1.8MJKg ; Po = 6bar
Centerline data
Hinge line
Flat plate
Separation
Reattachment
a)Images of Goertler vortices (at about 2mm pitch) on a 15°ramp in ahypersonic flow atM = 8.15 (thin-film sensor; AGA 780):
a) coarse (acquired, raw) image; b) sensor and camera restoration.
b)
21mm
1990ON THE RAMP
DE LUCA L, CARDONE G and CARLOMAGNO GM : Image Restoration in Thermo-fluid-dynamicApplications of IR Digital Imagery, in Lettington A.H. ed.,Infrared Technology and Application, SPIE Vol.1320, 448-457, ISBN 9780819403810 (1990)
Agema 782100x100 px
PICCOLO TUBE(De-icing of a wing leading edge, heated thin foil)
Meola C, Carlomagno GM, Riegel E and SalvatoF, An experimental study of an anti-icing hot air spray-tubesystem, Proc. 19th Congr. Int. Council Aeronautical Sciences (ICAS), Vol.3, pp. 2345-2351, Anaheim, (1994).Imbriale M, Ianiro A, Meola C and Cardone G , Convective heat transfer by a row of jets impinging on a
concave Surface,Int. J. Thermal Sci.,75, 153-163 (2013)
Standard conditions, no ice
With ice
Ice formation and accretion
Wing de-icing with piccolo tube
AIRPLANE WING
The test article includes theleading edgeofa NACA 0012 wing profile (1.5m chord),stopped at about 1/10 of the chord, withinside a spray (piccolo) tube at 4% of thechord to simulate the de-icing device.
The profile is 0.2m span-wise, made of anAISI foil (40µm thick) and lodged inside twoadaptorsto apply voltage difference.
The infrared camera (CEDIP Jade III, cooledFPA 320x240 InSb pixels, 3.8-5.3µm band,sensitivity 20mK at 300K) views thefoil sideopposite to the jet impingement one, bothfrom thefront and theback.
here, d and p are resp. hole diameter and pitch; φ φ φ φ is the jets inclination
anglewith respect to the wing chord
Holes
Piccolo
Since we are looking at athree-dimensional surface, a geometrical cameracalibration procedure, with the thermal images of the calibration target, isnecessary.
Then the plate is movedback and forth, withinmeasurement domain, toperform a geometricalcalibration.
Therefore, a thermal 3Dimage can be fullyreconstructed.
The target calibration plateis madeof an Al plate, 120x120mm2, with17x17 (289) holes, 2.2mmdiameterand 10mm deep, so to behavealmost asblack bodies.
3D TEMPERATURE RECONSTRUCTION FOR d = 4mm, φφφφ = 30°, M = 1.0 AND p/d= 15:
(a) Wall temperature Tw (with foil heating);
(b) Adiabatic wall temperature Taw (without foil heating).
Taw [K]Tw [K]
Nu = hd/λλλλ
Imbriale M, Ianiro A, Meola C and Cardone G , Convective heat transfer by a row of jetsimpinging on a concave Surface,Int. J. Thermal Sci.,75, 153-163 (2013)
INFLUENCE OF JETS PITCH ON Nu; M =1.0 AND φ φ φ φ = 50°(a) p/d= 5; (b) p/d= 10; (c) p/d= 15; (d) Numean(spanwise) vs. x/c
FLOW IN A ROTATING U CHANNEL(e.g., internal cooling of turbine blades; heated thin foil)
Gallo M, Astarita T and Carlomagno GM , Thermo-fluid-dynamic analysis of theflow in a rotating channel with a sharp U turn,Exp. .Fluids, 53, 201-219 (2012)
FLOW IN A ROTATING U CHANNEL
The effects of rotation, as inturbine HT blades, change stronglythe thermo-fluid-dynamic behavior of the flowin a channel.
This happens becausein a rotating channel with an U turnthere is interaction between the following forces:
• Pressure gradients causing the flow in the main direction
• Coriolis forces
• Centrifugal forces
The resulting flowfield is highly three-dimensional(especiallyin the turns) and this event affects the heat transfer coefficientdistribution.
This is why the problemwas studied with bothParticle ImageVelocimetry(PIV) andInfraRed Thermography(IRT).
EXPERIMENTAL APPARATUS ( WATER )
BY-PASS
CIRCUIT
PUMP
ORIFICE
FLOW-METER
TANK
CHANNEL
ROTATION AXISw
HEAT EXCHANGER
DIGITAL MAGNETIC
PICKUP SENSOR
000,20 ==µ
ρVDRe
Rotation number
Reynolds number
Trailing wallLeading wall
Static case (both walls)
COMPARISONS OF Nu/Nu* DISTRIBUTIONS
y/D
z/D
x/D
IN
OUT
Axis ofrotation
Sketch of the test region
leading wall: z/D = 0
trailing wall : z/D = 1
hD
Nuk
= ; Nu* = 0.024 Re0.8 Pr0.4
Nu/Nu*
0.3 ==V
DRo
ω
ωωωω
Re= 20,000
Leading wall
Trailing wall
Gallo M, Astarita T and Carlomagno GM, Thermo-fluid-dynamic analysis of the flow in arotating channel with a sharp U turn,Exp. Fluids, 53, 201-219 (2012)
0.3 ==V
DRo
ω
Giuseppe Ceglia
qc=���
��� ���
�
�
RaL= ����
�
������
D
L
qc
W
T = const
Vila CS, Discetti S, Carlomagno GM, Astarita T, Ianiro A, On the onset of horizontal convection, Int. J. Thermal Sciences, 110, (2016) 96-108
Main dimensionless parameters
• Prandtl number Pr= � �⁄ ;
• Rayleigh number RaL=Pr·GrL= �� ��
��;
• Aspect ratio A = D/L.
ONSET OF HORIZONAL NATURAL CONVECTION(Variable thermal boundary condition on a horizontal plane)
g
ONSET OF HORIZONAL CONVECTION
Schematic of the experimental apparatus
Vila CS, Discetti S, Carlomagno GM, Astarita T, Ianiro A , On the onset of horizontalconvection,Int. J. Thermal Sciences, 110, (2016) 96-108
A = D/L = 0.5; L = 300mm; Fluid: water
Schlieren visualization of the evolution of flow features for ��� ! ". #$" "%
&/()*+ = 0.2 0.7
1.0 2.0
ONSET OF HORIZONAL CONVECTION
,/-./ = . %0 ,/-./
= . 1
,/-./ = ". ,/-./
= %.
IMPINGING JETS(e.g., for cooling purposes; heated thin foil)
Carlomagno GM and de Luca L, Infrared thermpgraphy in Heat Transfer, in Yang WJ ed., Handbook of FlowVisualization, 531-553, Hemisphere (1989)Violato D, Ianiro A, Cardone G And Scarano F, Three-dimensional vortex dynamics and convective heattransfer in circular and chevron impinging jets,Int J Heat Fluid Flow , 37, 22–36 (2012)Greco CS, Ianiro A, Astarita T and Cardone G, On the near field of single and twin circular synthetic air jets,Int. J. Heat Fluid Flow, 44 (2013) 41-52.Greco CS, Ianiro A and Cardone G, Time and phase average heat transfer in single and twin circular syntheticimpinging air jets,Int. J. Heat Mass Transfer, 73 (2014) 776–788.Carlomagno GM and Ianiro A , Thermo-Fluid-Dynamics of Submerged Jets Impinging at Short Nozzle-To-Plate Distance: A Review, Exp. Therm. Fluid Sci., 58, 15-35 (2014)
ELECTRONIC COOLING
Classical devices to cool electronics:
• Fan and/or impinging jets
• Heat Sink
• High conductivity materials
TOMOGRAPHIC PIV ( 3D-3C)Tomographic PIV is a very powerful research tool.
TomoPIV is an innovative experimental technique, based on amultiple camera system,three-dimensional volume lightingand 3D reconstruction ofparticles velocity fieldwithin the whole measurement volume.
Tomographic PIV experimental apparatus for impinging jets
(transparent)
Discetti S, Astarita T, A fast multi-resolution approach to tomographic PIV, Exp Fluids, 52 , pp. 765-777 (2012)
Re= 5,000
Velocity in red; vorticity in blue
TOMOGRAPHIC PIV ( 3D-3C)Tomographic PIV is atime-resolvedresearch tool.
Besides what is encountered in standard nozzles,chevron nozzlesgenerateazimuthal instabilities,already in the jet shear layer, which induce anincrease of the heat transfer in the impingementregion. The noise they produce is much lower.
The ability to improve mixing of streamwisevortices appears to be instrumental inenhancingimpingement heat transfer with chevron nozzles.
standard nozzle chevron nozzle
RV radial vortices SR streamwise structures
VIOLATO D, IANIRO A, CARDONE G and SCARANO F ,Three-dimensional vortex dynamics and con-vective heat tran-sfer in circular and chevron impinging jets,Int. J. Heat FluidFlow, 37 (2012) 22–36
NuH/D = 4
PIV
IR
NEW PERSPECTIVES: SYNTHETIC JETS
� Zero net mass flow rate.
� Are generated by means ofloudspeaker, or a diaphragmmovement in a cavity.
� Can be used in electroniccooling and flow controlapplications.
Flow control (Amitay M, et al., 1997)
Impinging synthetic jet
(Murray D. B.)
PiezoceramicLoudspeaker
De Luca L, Girfoglio M and Coppola G, Modeling and experimental validation of the frequencyresponse of synthetic jets actuators, AIAA Journal , 52(2014), 1733-1748
SYNTHETIC JETS (FLUID DYNAMICS)
23
456 7
where 7 is a number whose value is 1and 0,16 for plane two-dimensionaland axisymmetric jets, respectively,Re the Reynolds numberand S theStrouhal number(S = Vm/2π f D).
Holman R, Utturkar Y, Mittal R, Smith BL andCattafesta L. Formation criterion for synthetic jets,AIAA J,43 (2005) 2110-2116
Therefore, synthetic jets are produced by the interactionsof a train ofvortices that are typically formed by alternating momentary ejectionand suction of fluid across an orifice(Glezer A, Amitay M , Synthetic jets,Annu.Rev. Fluid Mech,34 (2002) 503-529.
The formation criterion for syntheticjets is:
Greco CS, Ianiro A, Astarita T andCardone G, On the near field of singleand twin circular synthetic air jets,Int. J.Heat Fluid Flow, 44 (2013) 41-52.
Average flow fieldInstantaneous flow field
Phase averaged velocity
SYNTHETIC JETS (HEAT TRANSFER)
Greco CS, Ianiro A and Cardone G, Time and phase average heat transfer in single and twincircular synthetic impinging air jets,Int. J. Heat Mass Transfer, 73 (2014) 776–788.
The synthetic jet heat transfer is found to be comparable with thecontinuous axisymmetric jet andexpected to be betterat high Reynoldsnumber.(Chaudhari M, Puranik B and Agrawal A , Heat transfer characteristics of syntheticjet impingment cooling,Int. J. Heat Mass Transfer,53 (2010) 1057-1069)
Further understanding of theheat transfer mechanisms couldbe accomplished by exploitingtime-resolved measurementsof heat flux, which is theobjective of ongoing research(Astarita, Cardone & Ianiro).
Re= 4,200; z/D = 2
Phase averaged Nusselt number
• Acoustic excitation (Liu & Sullivan 1996);
• Application of swirl (Ianiro & Cardone 2012), or chevron (Violato & al. 2012);
• Introduction of perforated plates between nozzle and target plane (Lee et al 2002).
• Introduction of mesh screens within the nozzle (in particular fractal grids);
Violato et al,
IJHFF (2012)
Popiel, ETFS (1991)
El Hassan et
al, POF (2013)
Carlomagno and
Ianiro, ETFS (2014)
ACTUAL FRACTAL GRID
L0
10mm
t0
1mm
Lr
4
tr
4
Repeat the same pattern several time by scaling its dimensions
t0
L0
t1
t2
L1
L2
Impossibile v isualizzare l'immagine.
tr = t0
t2Cafiero G, Greco CS, Astarita T, Discetti S, Flow field features of fractal impinging jets atshort nozzle to plate distances,Exp Therm Fluid Sci, 78, 334-344 (2016)
Cafiero G, Greco CS, Astarita T, Discetti S, Flow field features of fractal impinging jets atshort nozzle to plate distances,Exp Therm Fluid Sci, 78, 334-344 (2016)
GRID
h
from Hurst & Vassilicos, POF (2007)
Effective meshlength
Grid solidity
REGULAR GRID
M 2.4mm
b 0.4mm
FRACTAL GRID
L0
10mm
t0
1mm
JWG Jet Without Grid
RG Regular Grid
FG Fractal Grid
• Strong HT enhancement
in the stagnation region.
• Cross-shaped Nu map.
• Double peak due to
ring vortices;
• Stagnation point heat
transfer decreases as
the distance increases.
• Multi-channel behaviour
• Several local maxima in
the 9: distribution.
RG
FG
JWG
m&
CONCLUDING REMARKS
• provides a fulltwo-dimensionalinformation• is anon-contact technique• allows a fullycomputerized image processing
Infrared Thermography is an innovative methodology forheattransfer studies, that we can use to either performnon-destructivetesting as well as tomeasure convective heat fluxes, its meanfeatures being:
The presented results were concerned with some significantexperiments carried out during the past several years by theresearch group the presenter belongs to.
Through these results, it is proved thatinfrared thermographyisable to yieldvaluable informationin aerospace applications about:• non-destructive evaluation of materials, markedly composites,• accurateheat transfer measurementsin complex fluid flows,
especially if coupled withPIV.
CERCANDO DI FARLO DA SOLO CERCANDO DI FARLO DA SOLO CERCANDO DI FARLO DA SOLO CERCANDO DI FARLO DA SOLO
Caro Signore,
Le sto scrivendo in merito alla sua richiesta di maggiori informazioni sul mio infortunio ricordandole che, nella casella no. 3 del rapporto di infortunio, io ho scritto come causadello stesso: Cercando di farlo da solo.
Nella sua lettera, lei mi chiede di essere più esplicito e spero che i dettagliriportati di seguito saranno sufficienti.
Io sono un muratore e, alla data dell’infortunio, stavo lavorando da solo sul tetto di un edificio nuovo di sei piani.
Completato il mio lavoro, ho scoperto che sul tetto mi restavano circa 200 chili di mattoni da portar via, calandoli al suolo.
Piuttosto che lungo le scale, ho deciso di calare i mattoni in un bidone, utilizzando una carrucola che, fortunatamente, si trovava su un lato del tetto al di sopra del sesto piano.
Dopo aver fissato la fune a livello stradale, sono andato sul tetto e ho caricato tutti i mattoni nel bidone. Poi, ritornato sulla strada, ho sciolto la fune per calare lentamente i 200 chili di mattoni.
Però, lei noterà che nella casella no. 11 del mio rapporto di infortunio io ho indicato che peso circa 80 chili.
A causa della mia sorpresa per essere stato strattonato dalla strada e per il mio spirito di conservazione, non ho lasciato la fune, tenendola stretta. E’ superfluo dire che ho iniziato a salire celermente lungo il lato dell’edificio.
In prossimità del terzo piano ho incontrato il bidone che scendeva e questo spiega le incrinature del mio cranio e delle mie clavicole.
Un poco rallentato, ho continuato la mia veloce salita fino a che le dita della mia mano destra si son trovate con due falangi incastrate nella carrucola. Questo spiega la mia mano fratturata.
Per fortuna, la mia presenza di spirito non mi aveva abbandonato e sono stato capace di tenere la fune ben stretta, nonostante il dolore.
Tuttavia contemporaneamente, il bidone di mattoni era sbattuto al suolo e il suo fondo si era staccato, facendo uscire tutti i mattoni.
Senza i mattoni, il peso del bidone era diventato circa 20 chili.
Le ricordo che come riportato nella casella no. 11 del rapporto di infortunio, salvo un po’ di sangue versato, io pesavo ancora circa 80 chili. Quindi ho cominciato una rapida discesa sul lato dell’edificio.
In prossimità del terzo piano ho incontrato nuovamente il bidone che saliva. Questo spiega le due caviglie rotte e le lacerazioni sulle gambe e sulla parte bassa del mio corpo.
L’incontro col bidone mi ha rallentato abbastanza per evitare grosse lesioni quando sono atterrato sul mucchio di mattoni, per cui, per fortuna, si sono schiacciate soltanto tre vertebre.
Debbo comunque riferirle che, mentre ero steso lì, dolorante sul mucchio di mattoni, incapace di alzarmi, guardando il bidone vuoto sei piani più in alto, ho perso la mia prontezza di spirito e ho mollato la fune.
Il bidone vuoto pesava più della fune per cui mi è piombato addosso fratturandomi entrambe le gambe.
Spero di avere fornito tutte le informazioni da lei richieste su come è avvenuto l’infortunio.
CERCANDO DI FARLO DA CERCANDO DI FARLO DA CERCANDO DI FARLO DA CERCANDO DI FARLO DA SOLO ?SOLO ?SOLO ?SOLO ?
NO !!!!!!!!!!!!
Meglio avere ottimi collaboratori
(che quì, ovviamente, ringrazio)
The total involved sites
WE ARE OVER
THANKS FOR LISTENING
CHIAO TO EVERYBODY
