What is meant by the term nominal design in connection with a radial-flow gas turbine rotor? Sketch the velocity diagrams for a 90° IFR turbine operating at the nominal design point. At entry to a 90°IFR turbine, the gas leaves the nozzle vanes at an absolute flow angle, α2, of 73°. The rotor-blade tip speed is 460 m/s and the relative velocity of the gas at rotor exit is twice the relative velocity at rotor inlet. The rotor mean exit diameter is 45% of the rotor inlet diameter. Determine
a. the exit velocity from the rotor;
b. the static temperature difference, T2 - T3, of the flow between nozzle exit and rotor exit Assume the turbine operates at the nominal design condition and that Cp = 1.33 kJ/kg K.