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MAE 112 Propulsion
Homework Assignment #6
Due: February 26, 2010
1)
Suppose we had two parallel flows, one at a stagnation temperature of 1925
R and
the other at 2900
R.
Each flow had a stagnation pressure of ten atmospheres, a value of
= 1.25, and a value of c
p
= .32 Btu/1bm
R.
The colder flow has twice the mass flow of
the hotter flow. Calculate the total thrust from nozzle expansion in each of the following
two cases.
a)
The flows are mixed adiabatically at constant pressure and then expanded to ambient
pressure of 0.9 atmosphere in one nozzle.
b)
Each flow is expanded to the 0.9 atmosphere ambient pressure through a separate
nozzle.
2) Consider a turbofan engine flying at a Mach number of 0.85 with an ambient pressure
of 0.8 atmosphere and an ambient temperature of 490
R.
The intake has .98 polytropic
efficiency. The air is divided with a bypass ratio of 6 into a primary and a secondary (or
bypass) flow at the exit of the air intake.
The primary flow passes through a fan and
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 Winter '09
 LaRue

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