Circumferential speed

The circumferential speed (➔u) is the velocity of a point particle performing a circular motion. This can be a point particle of a rotating pump shaft or a rotating impeller. The following relationship exists between the radius (r) of the point particle and the angular velocity (➔ω):

In turbomachinery design, the circumferential speed (➔u), together with the relative velocity (➔w) and the absolute velocity (➔c) form the velocity triangle.

The circumferential speed at relevant locations of the impeller has a marked influence on the suction characteristics, noise development and strength of the rotating components of centrifugal pumps.

Typical circumferential speeds (at the impeller outlet) range between 20 and 60 m/s, in exceptional cases up to 140 m/s.

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