The velocity of flow through the impeller is constant and equal to 2.5 m/s. The vanes are set back at an angle of 400 at outlet. If the outer diameter of the impeller is 500 mm and width at outlet is 50 mm, determine: i) Vane angle at inlet, ii) Work done by impeller on water per second and iii) Manometric efficiency.

Given:

$N = 1000 \hspace{0.05cm} rpm, H_m = 40\hspace{0.05cm}m, V_f = V_{f1} = V_{f2} =2.5\hspace{0.05cm}m/s\\ \phi = 40^\circ, D_2 = 500\hspace{0.05cm}mm = 0.50\hspace{0.05cm}m\\ D_1 = \frac{D_2}{2} = 0.25\hspace{0.05cm}m, B_2 = 0.05\hspace{0.05cm}m$

Solution:

$u_1 = \frac{\pi D_1N}{60} = \frac{\pi \hspace{0.05cm}\times\hspace{0.05cm} 0.25\hspace{0.05cm} \times\hspace{0.05cm} 1000}{60} = 13.09\hspace{0.05cm}m/s$

$u_2 = \frac{\pi D_2N}{60} = \frac{\pi …