Derive the following expression for the critical pressure ratio (rc) in a steam nozzle where steam enters with initial velocity and the flow is accompanied with friction:
Where :
C1 = Initial steam velocity
r1 = Initial steam pressure
h = small stage expansion efficiency = hn
n1 = actual exponent of expansion
v1 = initial steam specific volume
(ii) Show the effect of variation of back pressure on distribution of pressure and velocity all along in a convergent-divergent nozzle.