Question

03-6: A Pelton wheel is supplied with 1.2 kg/sec of water at 20 m/sec. the buckets rotates on a mean diameter of 250 mm at 800rev/min. The deflection angle is 165° and friction is negligible. Determine the diagram power. Draw the vector diagram to scale and determine Δ v

Answer 1

m_1 = 1.2kg/sec v_1 = 20 m/s Bucket mean dicks d = 250 mm N = 800 rev/min there is no friction therefore 4 remains same u = u_1 = u_2 u = rdn/60 = r times 0.250 times 800/60 u = v_1 - u u = 10.472 m/s Vr_1 = v_1 -u_1 v_r1 = 20-10.42 material implication 9.53 m/s in the absence of friction V_r1 = V_r2 then V_w2 = V_r2 cos 25 - y_2 where Vr_2 s = Vr_1 = 9.53 y_2 s = 10.472 m/s V_w2 = 9.53 cos 25 - 10.472 V_w2 = -1.837 m/s then outlet velocity triangle then V_w2 = 1.837 m/s then diagram power P = m (Vw_1 - V_w2)u P = 1.2 (20 - 1.837) times 10.472 P = 228.2435 watt