INLET RECIRCULATION IN PARTLOAD REGIMES – RADIAL PUMP

Abstract

Partload regimes of all types of centrifugal pumps are strongly and unfavorably affected by an influence of an inlet recirculation. This negative phenomenon usually occurs at pump suctions, when a circumferential velocity component of the fluid flow (derived from a rotational speed of a rotor) is dominant over an axial velocity component. Such physical effect goes hand in hand with a creation of a pump-head instability, a decrease of an overall efficiency, an excessive noise and pressure pulsations and even a possible cavitation formation. The introduced technical problem was tested/examined for a radial centrifugal pump Ns375 with a volute (spiral casing) and an axial intake domain with two potential countermeasures. Both, a physical experiment and transient numerical simulations were employed and compared on crucial levels.