1 Due: February 5, 2010 MAE 112 Homework Assignment #4 1. Suppose a particular jet engine had an entrance cross-sectional area of 2.0 ft 2 and an exit cross-sectional area of 6.0 ft 2 . The air-fuel mass ratio is 30 at one particular operating point. The flight velocity is 550 miles per hour and the exhaust velocity is 4000 feet per second. Consider normal octane (n-octane) as the fuel and assume normal atmospheric conditions with perfect expansion at the nozzle exit. (a) What is the thrust? (b) What is the efficiency? fuel with associated rate n consumptio Energy Power Propulsive Here 2. Do Problem 18, Pages 214-5, Hill & Peterson. Note that specific thrust is defined as thrust per unit mass flow of air. It is used to normalize and to be able to compare engines of different sizes against each other. 3. Do a preliminary design on a ramjet engine which produces 10,000 1bf of thrust. Size constraints limit the intake cross-sectional capture area to 1.25 square feet. The engine is
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