Vaporization of JP-8 Jet Fuel in a Simulated Aircraft Fuel Tank ...

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Fuel to Air Mass Ratio 0.045 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0 LFL Range Increasing Mass Loading 0 500 1000 1500 2000 2500 3000 Time, seconds M.L.=300 kg/m3 M.L.=31.5 kg/m3 M.L.=0.5 kg/m3 Figure 6.9. Mass loading effects on mixture flammability using the FAR rule [26]; heated tank at sea level with constant ambient temperature and pressure. Le Chatelier's Ratio 1.2 1 0.8 0.6 0.4 0.2 0 Le Chatelier's Flammability Limit Increasing Mass Loading 0 500 1000 1500 2000 2500 3000 3500 Time, seconds M.L.=300 kg/m3 M.L.=31.5 kg/m3 M.L.=0.5 kg/m3 Figure 6.10. Mass loading effects on mixture flammability using Le Chatelier’s flammability rule [27]; heated tank at sea level with constant ambient temperature and pressure. 57
6.2.2 Fuel Tank Under Varying Ambient Conditions The FAR rule and Le Chatelier’s ratio rule were again used to determine the level of flammability for the second example, an initially heated fuel tank exposed to simulated flight conditions. Figures 6.11 and 6.12 show, respectively, the calculated FAR and the calculated Le Chatelier’s ratio, both calculated using the fuel compositions with flashpoints of 115°F and 120°F [21]. From figure 6.11, the mixture was not in the flammable region until the ambient pressure was decreased during ascent. This was due to the fact that the component vapor pressures are functions of temperature only, and although the ambient pressure outside of the fuel tank was decreasing, the component vapor pressures are fixed for the liquid fuel temperature. So in order for the fuel vapors to exert the same pressure on the enclosure at a reduced ambient pressure, more fuel molecules were required to vaporize into the ullage space. Le Chatelier’s rule was again seen to be more conservative than the FAR rule by comparing figures 6.11 and 6.12, so the FAR rule will again be used to assess the effects of fuel temperature and mass loading on flammability for this flight profile test. The liquid temperature effects on flammability are shown in figures 6.13 and 6.14. Three different liquid temperature profiles were used in the model to calculate the FAR and LCR using the fuel composition of the 115°F flashpoint fuel. The original average measured liquid temperature profile is referred to as TLIQ and the other two profiles were obtained by adding 5°F and 10°F to TLIQ and are referred to as TLIQ+5 and TLIQ+10, respectively. Figure 6.13 includes the predicted LFL range using the FAR criterion from reference [26]. It shows that for the conditions tested, the tank ullage was within the LFL range for part of the level flight at 30,000’ altitude. However, increasing 58
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DOT/FAA/AR-TT09/42 Air Traffic Orga
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1. Report No. DOT/FAA/AR-TT09/42 4.
Page 5 and 6:
ABSTRACT OF THE THESIS VAPORIZATION
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DEDICATION This thesis is dedicated
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5.0 RESULTS 32 5.1 Validation Tests
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5.7 JP-8 fuel vaporization at sea l
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LIST OF TABLES Table Page 2.1 Compa
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develop procedures to lessen the li
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When it was determined that a CWT e
Page 19 and 20: 1.3 Objectives of the Thesis The ul
Page 21 and 22: has more additives, such as an anti
Page 23 and 24: equilibrium is dynamic in nature, b
Page 25 and 26: factor in making these calculations
Page 27 and 28: Volume Fraction, % 30 25 20 15 10 5
Page 29 and 30: 0.035±0.004 at 0°C [26]. The publ
Page 31 and 32: Raleigh numbers which were of order
Page 33 and 34: loading of fuel and be subjected to
Page 35 and 36: pressures. The heaters in the pump
Page 37 and 38: Figure 3.1. View of top surface of
Page 39 and 40: the tank and the ullage vapor conce
Page 41 and 42: attempted, but provided inaccurate
Page 43 and 44: pump that could draw samples from a
Page 45 and 46: 5.0 RESULTS When inputting the expe
Page 47 and 48: etween measured and predicted value
Page 49 and 50: 5.1.2 Isooctane Fuel Vaporization T
Page 51 and 52: higher altitudes, as continuous sam
Page 53 and 54: Temperature, Deg. F. 140 120 100 80
Page 55 and 56: Temperature, Deg. F. 70 60 50 40 30
Page 57 and 58: % Propane Equivalent 2 1.5 1 0.5 0
Page 59 and 60: % Propane Equivalent 3 2.5 2 1.5 1
Page 61 and 62: liquid fuel the mass of fuel evapor
Page 63 and 64: In the beginning of the test, the l
Page 65 and 66: 6.2 Flammability Assessment 6.2.1 F
Page 67 and 68: average measured liquid temperature
Page 69: Fuel to Air Mass Ratio 0.05 0.045 0
Page 73 and 74: Fuel to Air Mass Ratio 0.045 0.04 0
Page 75 and 76: Fuel to Air Mass Ratio 0.05 0.04 0.
Page 77 and 78: temperature measurements would be r
Page 79 and 80: Which is appropriate for Raleigh nu
Page 81 and 82: d dt ( mg c pgTg ) = hb Ab ( Tb −
Page 83 and 84: APPENDIX C: EXPERIMENTAL FUEL FLASH
Page 85 and 86: 13. Fuel Flammability Task Group, A
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