MAE 112 PROPULSION FIRST MIDQUARTER EXAM February 7, 2008 Do all three problems in eighty-five minutes. Books, notes and calculators can be used freely. I. Consider a liquid-propellant rocket engine where one hundred kilograms per second of liquid oxygen plus 110 % of the stoichiometric amount of liquid hydrogen flows into the combustion chamber at 30 atmospheres of pressure. The liquids, hydrogen and oxygen, are introduced at their boiling points: 20 K and 90 K, respectively. Hydrogen has a heat of vaporization of 451.9 joules/ gm; assume its vapor has a specific heat at constant pressure of 14.2 joules / (gm o K). Oxygen has a heat of vaporization of 212.9 joules/ gm; assume its vapor has a specific heat at constant pressure of 0.920 joules / (gm o K). The average specific heat at constant pressure for gaseous H 2 O can be taken as 2.09 joules/(gm o K). The gaseous flow through the combustor has a very low Mach number. (a) Establish
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