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Q5. Steam flows through one stage of a pressure compounded impulse turbine at the rate of 1.5 tonne/hour. The steam enters the nozzle with a velocity of 170 m/s and a pressure of 30 bar, 400℃ respectively

The nozzles are set at 20° to the plane of rotation and expand the steam with an isentropic efficiency of 95% to a pressure of 15 bar. The blades have an exit angle 10° less than their inlet angle and a velocity coefficient of 0.9.

(a) Calculate the absolute velocity of the steam leaving the nozzles. (4)

(b) Draw the stage velocity vector diagrams to a scale of 1 mm = 5 m/s.(6)

(c) Determine EACH of the following for the stage:

(i) The diagram power; (2)

(ii) The axial thrust; (2)

(iii) The diagram efficiency. (2)

Note: Blade speed ratio =   cos⁡α_i/2