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Abstract
A special test rig for study of cavitation in centrifugal pump is designed and constructed in the laboratory of Prof. Bassyouni Ahmed Khalifa at Faculty of Engineering Shibin El-Kom. The rig was designed so that the flow rate ratio (pump flow rate/ optimum flow rate), suction pressure, pump rotational speed and water temperature could be varied independently under cavitating condition. The pump suction side and front shroud of its impeller are made from transparent perspex to permit visual cavitation inception.
An experimental study of circulatory flow in the pipe immediately in the front of the pump impeller at varies pump rotational speeds and flow rates is presented. The distribution of velocity at low flow rates is measured at impeller inlet. The onset and structure of the flow recirculation at the inlet are investigated experimentally. The results showed that the recirculating flow appeared for flow rate ratios Q/Qopt< 0.8 and there is no recirculating flow for flow rate ratios Q/Qopt > 0.8. On the basis of the velocity distribution an empirical formula is obtained to describe the relation between the ratio of meridional velocity with recirculation flow to the meridional velocity without recirculation flow (Cm7Cm) and the flow rate ratio (Q/Qopt)-
The effects of flow rate ratio, pump rotational speed and water temperature on
performance and cavitation inception of a centrifugal pump are presented
experimentally. The tests were carried out at different flow rate ratios and different
y rotational speeds and different water temperature. The ratio of flow rate to optimum
flow rate was varied from 0.3 to 1.1, while the speed and temperature were varied from 1500 rpm to 3000 rpm and from 20°C to 90°C respectively.