At the inlet of a centrifugal pump impeller the local flow speed is and the ambient…

PHYSICS · Multi-part · Fermi University Physics · Fluids & Continuum Physics · Solid continuum mechanics and complex fluids · Solid continuum mechanics and complex fluids

Bending, Ringing, Breaking and Flowing, Ch Bubbles, drops and cavitation

Problem

At the inlet of a centrifugal pump impeller the local flow speed is

U = 15\,\mathrm{m\,s^{-1}}

and the ambient (suction-side) pressure is

p_\infty = 80\,\mathrm{kPa}

, in water at

20^{\circ}\mathrm{C}

with

p_v = 2.3\,\mathrm{kPa}

and

\rho = 1000\,\mathrm{kg\,m^{-3}}

. Tests on the blade shape give a minimum pressure coefficient

C_{p,\min} = -1.5

. ((a)) Compute the cavitation number

\sigma_c

of the flow. ((b)) Decide whether the impeller cavitates at this operating point, and justify the criterion used.

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