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MAE 112
PROPULSION
MIDQUARTER EXAM
February 10, 2010
Do all three problems in onehundredandten minutes.
Books, notes and calculators can
be used freely. No computers or communication devices are allowed. If tables or charts
are used rather than formulas, identify the source.
1.
Consider a rocket nozzle with initial pressure and temperature of thirty atmospheres
and 5100
R.
The value of
= 1.2 and the value of c
p
= .32 Btu/1bm
R.
The throat area
is 0.5 ft
2
.
The flow is underexpanded to 0.3 atmospheres with the ambient pressure of
0.15 atmosphere.
Assume 100% polytropic efficiency for the nozzle flow. Calculate:
(a)
the characteristic velocity c*, (b) nozzle exit velocity U, (c) the mass flow, (d) effective
exhaust velocity c, (e) the thrust coefficient, and (f) the thrust.
2.
Consider a ramjet in flight at a Mach number of 2.5 with ambient conditions at 270 K
and 0.7 atmosphere of pressure. The air capture area in the free stream is 0.25 square
meter. The inlet design involves first a wedge that deflects the stream by an angle of 20
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 Winter '09
 LaRue

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