Second Paper: The Correlation of Cavitating Performance for a Centrifugal Pump Handling Various Liquids

Abstract

Following a specific model for the behaviour of a centrifugal pump under advanced cavitation conditions a parameter is derived for the correlation of pump performance when handling different liquids. The parameter's development is based on bubble growth theory, assuming that for the cavitation condition being investigated the bubble radius is much greater than that of the initial nucleus. Published data for a 3 per cent loss in pump head are then used to evaluate the parameter, and to compare it with the ‘thermal parameter’ and that suggested by Barenboim. Whilst all three parameters are reasonably successful with Salemann's data, all fail with Spraker's data. The author then argues that since the data are for limited cavitation conditions a strong Reynolds number influence can be expected, and it is shown that the product of this number (with an empirical fractional exponent) and the derived parameter results in good correlation for each pump. It is expected that the magnitude of the exponent will decrease as the degree of cavitation increases.