user
If i have a simple centrifugal pump 10cm in diameter going 2000 rpm, what would the velocity of water flowing out be?
alphonsio

The velocity is ~10.471975511965978 m/s

To estimate the velocity of water flowing out of a centrifugal pump, we primarily consider the tangential (peripheral) velocity at the outer edge of the impeller, since the water is flung outward due to centrifugal force.

Given:

  • Diameter of impeller = 10 cm = 0.1 m
  • Radius rr = 0.05 m
  • Rotational speed NN = 2000 RPM

We’ll first convert the rotational speed to angular velocity ω\omega, then compute tangential velocity.

Step 1: Convert RPM to radians per second

ω=2πN60=2π×200060≈209.44 rad/s\omega = \frac{2\pi N}{60} = \frac{2\pi \times 2000}{60} \approx 209.44 \, \text{rad/s}

Step 2: Calculate tangential velocity at the tip of the impeller

v=ω⋅r=209.44×0.05≈10.47 m/sv = \omega \cdot r = 209.44 \times 0.05 \approx 10.47 \, \text{m/s}

Conclusion:

The theoretical velocity of water exiting the pump is approximately 10.47 m/s.

This is an idealized estimate and assumes:

  • No losses due to friction, turbulence, or leakage
  • The pump design allows for maximum energy transfer to the fluid