Velocity Triangle for Centrifugal Pump

Velocity triangle for centrifugal pump is shown in Figure 9.18.

Figure 9.18 Velocity Triangle for Centrifugal Pump

Here,

• N is speed of impeller in rpm;
• D₁, D₂ are diameter of impeller at inlet and outlet, respectively;
• u₁, u₂ are tangential velocities at inlet and outlet, respectively;
• V₁, V₂ are absolute velocities of water at inlet and outlet, respectively;
• V_r1, V_r2 are the relative velocities of water at inlet and outlet;
• α is an angle made by absolute velocity V₁ at inlet with direction of motion of vane;
• θ is an angle between V_r1 and the direction of motion of vane;
• β, ɸ are the corresponding angles of α and θ at outlet;
• The water enters the impeller radially, therefore α = 0, V_ω1 = 0; and
• Work done per unit weight of water by impeller. Work done by impeller on water per second = ρQV_ω2u₂