NOZZLE
1.
What do you understand by critical pressure ratio? Show that critical pressure ratio for
a supersonic flow through a nozzle is = 0.546, when the steam entering the nozzle is
superheated
2.
Steam at 10 bar and 0.97 after expansion in a group of convergent nozzles to a pressure
of 0.15 bar flows in an impulse turbine which develops 150 kW of power with a steam
consumption of 8 kg / kWh. Determine (a) The pressure at throat, (b) The number of nozzles
required each of which is 6 mm diameter at the throat. It may be assumed that 10 % of the
overall isentropic enthalpy drop reheats the steam in the divergent portion of the nozzle.
3.
Saturated steam enters a converging–diverging nozzle at 3.0 MPa, 5 percent moisture,
and negligible velocity, and it exits at 1.2 MPa. For a nozzle exit area of 16 cm2, determine
the throat area, exit velocity, mass flow rate, and exit Mach number if the nozzle has an
efficiency of 90 percent.