Experimental startup characteristics of a prototype pump delivering tap water

As an important period of self-priming process, the startup process of self-priming pump is inevitable. In this paper, a small overhung self-priming centrifugal pump is tested to reveal the effect of startup time on startup performance. As a first step, the startup performance of the pump delivering water is tried firstly. Through testing, the transient characteristics of performance variables against time are emphatically analyzed in three lengths of startup time/duration and four typical steady flow rates. The test results show that with extension of the startup time, the steady rotational speeds present a slight rise trend. The flow rate curves overall rapidly rise and then grow slowly. The shorter the length of the startup time, the closer the head curves tend to be linear. Conversely, the head curve more likely can be best fitted by quadratic polynomial. At the beginning of rapid startup, there is a sudden-rise-and-sudden-drop oscillation phenomenon in the inlet static pressures curves, and a pressure impact phenomenon can be found in the outlet static pressure curves. However, the above two phenomena do not exist in the moderate and slow startups. The transient characteristics of dimensionless flow rate and head are associated with the length of startup time, while the dimensionless shaft power is not. There is no similarity in transient performance between rapid, moderate, and slow startup cases.