Abstract

Some Dynamic Processes Associated with Cavitation in Centrifugal Pumps
In this report attension was given to cavitation in centrifugal pumps, some indirect methods for observing the cavitation in these machines were discussed and the results of investigations of two single - stage pumps under various operarting conditions were presented. The investigations concerned selected dynamic quantities and characteristic curves suitable for indicationg the course of cavitation inside a pump. Measured and analyzed were such effects of cavitation like acoustical effects, vibrations and acceleration of impeller housing and also pressure pulsation on the suction side. Based on the power measurements, the conditions of cavitation were evaluated, the state where the pump characteristics were seemingly not affected by the cavitation having been recognized as the ,,no cavitation" state.

The purpose of the investigation under consideration was to choose from among the dynamic quantities registered that one which is most suitable for estimating the degree to which the cavitation has developed. This quantity should allow determining the permissible operating parameters of a pump on account of the durability of its components.

It was observed that acceleration was the most regularly behaving quantity from among those investigated. Its lowest value corresponds to the initial cavitation occuring before the deflection of pump characteristics. From the minimum of the accerelation function, presented as a function of the flow rate at various suction heads, a characteristic useful for the determination of the permissible, from the cavitation veiw-point, flow rate and suction head was obtained.