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IgnitionEnergyEPSolnLect18ME525Sp2011

# IgnitionEnergyEPSolnLect18ME525Sp2011 - 1 Example Problem...

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1 Example Problem Ignition Energy Lecture 18 ME 525 SP2011 Prof. Lucht Turns 8.16. How many times more ignition energy is required to achieve ignition of a fuel-air mixture at an altitude of 6000 m where P=47,166 Pa and T=248 K than at sea level with T=298 K? Discuss the implications of your calculation for high-altitude relight in aircraft gas turbine engines. Assume: Chapter 8 theory applies, p c constant , b T constant , 1 up k P c  , use empirical correlations of Metghalchi and Keck to calculate L S , assume that the fuel is isooctane.  , , 12 . 1 u LL r e f d i l ure f re f T P SS Y TP      Where , 2 ,2 298 , 1 2.18 0.8 1 0.16 0.22 1 f f Lre f M M dil TK P a t m SB B Y fraction of diluent in fuel air mixture    For isooctane, 2 1.13, 26.32 / , 84.72 / MM B cm s B cm s  For low-altitude conditions, 298 , 1 u P a t m , the flame speed for stoichiometric isooctane air: 22 ,, , 26.32 84.72 1.00 1.13 24.9 0 1 2.1 24.9 f M M dil u r e

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IgnitionEnergyEPSolnLect18ME525Sp2011 - 1 Example Problem...

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