4. For the subsonic axial-flow air expander specified, calculate the stagnation and static pressures and temperatures and the Mach number at the rotor-inlet plane (figure). Also find the rotor rotational speed and the nozzle-inlet blade height for constant-outer-diameter blading. Sketch the form of the complete turbine expansion on an enthalpy-entropy chart. The axial velocity will be constant at this design point. Mass flow, m= 2 kg/s Nozzle-inlet stagnation temperature, Toni 400 °C. Absolute nozzle-inlet stagnation pressure. Po.al=3 bars(= 3 x 105 N/m²) Mean diameter, d. 0.25 m. Blade height at rotor entry, I = 0.1d (= 1/2[d, - dnl). Flow angle at nozzle exit, a, 70° to axial direction. Drop in stagnation pressure in nozzle, Apo= 0.05 bar Rotor peripheral speed at mean diameter, = 0.5x (component of nozzle outlet velocity, Ca..). dsh dnb dm (N 3 4

Gas dynamics

5. For the subsonic axial-flow air expander specified, calculate the stagnation and static pressures and temperatures and the Mach number at the rotor-inlet plane (figure P2.5). Also find the rotor rotational speed and the nozzle-inlet blade height for constant-outer-diameter blading. Sketch the form of the complete turbine expansion on an enthalpy-entropy chart. The axial velocity will be constant at this design point. Mass flow, m = 2 kg/s Nozzle-inlet stagnation temperature, Tuni = 400 °C. Absolute nozzle-inlet stagnation pressure, Po,ni = 3 bars(= 3 x 105 N/m²) Mean diameter, dm = 0.25 m. Blade height at rotor entry, 1 = 0.1dm(= 1/2[ds - dn]). Flow angle at nozzle exit, a₁ = 70° to axial direction. Drop in stagnation pressure in nozzle, Apo = 0.05 bar Rotor peripheral speed at mean diameter, um = 0.5x (component of nozzle outlet velocity, Ce,1).

Each stage of an axial flow compressor is of 0.5 reaction, has the same mean blade speed and the same flow outlet angle of 30 degree relative to the blades. The mean flow coefficient is constant for all stages at 0.5. At entry to the first stage the stagnation temperature is 278 K, the stagnation pressure 101.3 kPa, the static pressure is 87.3 kPa and the flow area 0.372 m. Using compressible flow analysis determine the axial velocity and the mass flow rate.