Effect of rotational speed and flowrate on the startup characteristics of a pumps as turbine

Abstract

The startup process of pump as turbine (PAT) is actually unavoidable. In order to reveal the transient behavior of a small centrifugal pump reversing as a turbine during an atypical startup, transient experiments are carried out on PAT test rig in the case of two valve openings and four rotational speeds so as to obtain the evolution characteristic of the external performance parameters over time. Meanwhile, three dimensionless parameters are also employed to deeply reveal the transient characteristics. It is found that the shock phenomena in static pressure are prevalent at the outlet of PAT, and that it tends to lag and weaken with increasing stable rotational speed. All three dimensionless factors have maximum values at the initial stage of PAT startup, whereafter they demonstrate the different evolution characteristics.