A small rocket engine has the area-ratio- nozzle of the text ( , ) and a chamber pressure

PHYSICS · Multi-part · Fermi University Physics · Fluids & Continuum Physics · Waves, acoustics and compressible flow · Waves, acoustics and compressible flow

Signal Speeds in Fluids, Ch Oblique shocks, expansion fans and blast waves

Problem

A small rocket engine has the area-ratio-

2

nozzle of the text (

M_{\rm e}=2.20

p_{\rm e}=0.0939p_0

) and a chamber pressure

p_0=7.0\ \mathrm{bar}

. Treat the exhaust as a perfect gas with

\gamma=1.4

and the jet as two-dimensional. ((a)) At sea level,

p_{\rm b}=1.013\ \mathrm{bar}

. Find

p_{\rm b}/p_{\rm e}

and say whether the jet is over- or under-expanded. Find the lip-shock angle

\beta

, the inward turn

\theta

, the Mach number

M_2

behind the lip shock and

\theta_{\max}(M_2)

, and decide whether the shocks reflect regularly on the axis. ((b)) Higher up,

p_{\rm b}=0.40\ \mathrm{bar}

. Which wave stands at the lip? Find the fully expanded Mach number

M_{\rm j}

and the outward turn of the jet boundary. ((c)) Describe how the pattern of diamonds changes as the rocket climbs from sea level through the height at which

p_{\rm b}=p_{\rm e}

Browse the problem library