Assignment:
The steam from the nozzles of a single wheel impulse turbine discharges with a velocity of 600 m/s at an angle of 20 degrees. The blade wheel rotates at 3000 rev/min and the mean blade radius is 590 mm. The axial velocity of the stream at the exit from the blades is 164 m/s and the blades are symmetrical.
Sketch the annotated velocity triangles and calculate:
a) the blade inlet angle
b) the diagram specific work
c) the diagram efficiency
d) the blade velocity coefficient
e) Show that for symmetrical blading and no friction n_rot = 4(U/V_1)(cos(alpha_1) - (U/V_1)) and determine the optimum blade speed ratio and efficiency. Make a sketch of your results.