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lecture_11

# lecture_11 - 16.512 Rocket Propulsion Prof Manuel...

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16.512, Rocket Propulsion Prof. Manuel Martinez-Sanchez Lecture 11: Radiation Heat Transfer and Cooling Radiative Losses At throat of a RP1-LOX rocket, evaluate radiation heat flux c P 70atm = c D 0.21m = c T 3500K = O /F 2.2 = γ =1.25 M=25 g/mol o c x 0.3 ± 8 1 4 1 2 H O x 0.3 = 2 H x 0.1 ± 2 co x 0.1 ± γ γ− = γ + 1 throat 2 P 1 c P 38.85atm = co P 14.8atm = 2 H O P 12.0 at = m m m 2 H P 5.4at = 2 co P 4.3 at = = = = γ + throat c 2 T T 3111K 5600R 1 Assume slab if thickness L=0.9 t D 0.191m 0.63ft = = ( ) co PL 9.2ftatm = ( ) 2 H O PL 7.5ftatm = ( ) 2 H PL 3.4ftatm = ( ) 2 co PL 2.7ftatm = 16.512, Rocket Propulsion Lecture 11 Prof. Manuel Martinez-Sanchez Page 1 of 14

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CO Fig 4-22 for CO gas only to 2400 R 2 ft atm So, extrapolated to 9.2 ft atm, ( ) 2400R 0.1 ε ± at 2400 R. But ε falls rapidly with T. If we conservatively extrapolate linearly in Log ε (T). co ε would appear to go to ~ 0.005 or so. Hence, even though the gas is CO-rich, radiation by CO is negligible . 2 H O At , PL , Fig 4.15 gives T P 1atm = 7.5ftatm = ( ) 2 H o 5000R 0.18 ε = , and extrapolating a bit to T=5600R, . 2 H O 0.15 ε ± Fig 4.15 gives for o correct for finite and higher , use 4.16. Here, for , there is some significant effect of w ε w T P 0,P 1at = . m T w P T P w P L 7.5ftatm = w T P P 2 + . We have w T P P 12 38.9 25.5atm 2 2 + + = = way beyond the graph.
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