BRIEF OVER VIEW OF THE MINIMUM PERFORMANCE STANDARD FOR ENGINES describes geometry for a fixture loosely representing an aircraft engine nacelle describes

•BRIEF OVER VIEW OF THE MINIMUM PERFORMANCE STANDARD FOR ENGINES•describes geometry for a fixture loosely representing an aircraft engine nacelle•describes process to produce a representation of the current level of safety protecting these spaces•puts halon through an “obstacle course” looking for a specified performance•upon achieving the specified performance, pull out the halon and iterate to a quantity of a replacement repeating the same performance as halon•quantify replacement

•DISCUSSED SIMULATOR CONFIGURATION AND PROVIDED CURRENT SIMULATOR STATUS•provided schematic view of the simulator•discussed hot plates; plate heating configuration resolved, still need to get plate into the core section•discussed heating the air flow stream; will do it in 2 steps, one heat addition at the inlet and second heat addition from the heated surface of the simulator core•presented curve characterizing flow capacity of simulator; @65°F, range of 2-11 lbm/s and 15-80 compartment changes per minute•1-2 months remain to completion

•DISCUSSED HALONYZER DISCREPANCIES•fire testing in 1998 indicated fire test data timeline did not correlate with Halonyzer II timeline for distribution•performed in-house testing to evaluate nature and magnitude of discrepancy•determined the key discrepant factor was the transport of the sample through the sampling probe (tube to transport sample from the sample point to the transducer)•resulted in selecting a smaller probe•correction closely matches a near-square wave trace with a twenty foot long probe trace

•DISCUSSED HFC-125 SIMULATION OF HALON 1301 DISTRIBUTION•showed April 1998 test data•showed recent simulator test pairing; concentration magnitudes discrepant•attribute discrepancy to inconsistent weight measurements on the scale used to determine agent quantities•additional work during simulator distribution set up is planned•technical note is in editorial review soon to be published Douglas Ingerson

Federal Aviation AdministrationW.J. Hughes Technical CenterAtlantic City Int’l Airport, NJFire Safety section, AAR-422

Dimensions of Various Cross Section for the Nacelle SimulatorRo or H Ri or W area area comment

in in in^2 ft^2A - - - - transition ductB 11 0 380 2.64 exhaust nozzle cross sectionC 17.5 0 962 6.68 exhaust nozzle cross sectionD 24 12 1357 9.42 test section aft endF 24 12 1357 9.42 test section middleG 24 12 1357 9.42 test section inletH 21 6.51 1252 8.69 inlet diffuser middleJ 18 1.02 1016 7.06 inlet diffuser entranceK 18 0 1018 7.07 approach ductL 18 0 1018 7.07 straightening grillM 18 0 1018 7.07 straightening grill entranceN 35 35 1225 8.51 tube bank heat exchanger shellP 18 0 1018 7.07 transition ductQ 24 17.5 420 2.92 blower outletR - - - - supply blower, 3 hp, 22" dia. inlet

Douglas IngersonFederal Aviation Administration

W.J. Hughes Technical CenterAtlantic City Int’l Airport, NJFire Safety section, AAR-422

Nacelle Simulator Status

•Working on heating the core surface

•Need to mount hot plates

•Need to install two duct heaters at inlet

High Bypass Ratio Turbofan Nacelle Simulator






Nacelle Simulator AirFlow Characterization (3hp fan)

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mass flo, 23Oct98

mass flo, 27Oct98

mass flo, 9Nov98

mass flo, 24Nov98

air chngs, 23Oct98

air chngs, 27Oct98

air chngs, 9Nov98

air chngs, 24Nov98




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Conceptual Airflow Temperature Profile

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Comparing Analyzer Response for5% V/V Halon 1301, Varying Probes


Douglas IngersonFederal Aviation AdministrationW.J. Hughes Technical CenterAtlantic City Int’l Airport, NJFire Safety section, AAR-422

• Given the compartment ventilation rate (changes/min) in the nacelle is related to that of the analyzer probe.

• Variables given are describing : Q = volumetric flow rate V = internal volume of probe or nacelle A = internal cross sectional area of probe or nacelle L = length of probe or nacelle x dot = average gas flow velocity in probe or nacelle f = factor relating the two air change rates subscript “E”, related to engine nacelle subscript “T”, related to analyzer probe (tube)

• Formulation illustrates air change rates are dependent upon ratios of (neglecting complex flow interactions): lengths of the probe and nacelle gas stream velocities

For true “real-time” history, the transducer must see the gas flow at the same velocity the nacelle sees; the factor of {f * [LE / LT]} must approach 1.

One can treat the nacelle event as a source (as in source/sink relationships) because the total sampling volume from the nacelle flow is negligible; the factor {f * [LE / LT]} can be set to approach zero; therefore capturing the event with inconsequential time dilation considerations.

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Gas Concentration Data Disagreement with Fire Test

Data




The trace from the 1/8”ODx20 ft

long probe is approximately a

pure time displacement of the near-square

wave forms shown.


HFC-125 Simulation of a

Halon 1301 Distribution, April 1998



















HFC-125 Simulation of aHalon 1301 Distribution in the FAA

Nacelle Simulator, 20April1999



•Halon 1301 curves are translated along the time axis for clarity.

•the agent weights transferred to the fire extinguisher was not in accordance with the procedure to correctly simulate Halon 1301 with HFC-125.

•Generally agreeable qualitative behavior is still observed

Documents

BRIEF OVER VIEW OF THE MINIMUM PERFORMANCE STANDARD FOR ENGINES describes geometry for a fixture loosely representing an aircraft engine nacelle describes