Use of Steady-State Pump Head-Discharge Curve for Unsteady Pipe Flow Applications

An experimental pipeline system with a multistage centrifugal pump was used to study the effect of transient operations on the hydrodynamic performance of a centrifugal pump. Several transient flow operations were considered, ranging from very mild to severe transients. The dynamic relationship of total pressure rise across the pump to the flow rate was compared with that of the steady state. Deviation between the dynamic pump head and the value given by the steady-state curve at the same instantaneous discharge was established and found to be a function of the severity of the transient. It was found that severe flow conditions could cause this deviation to exceed 30% of the steady-state value. The use of the steady-state pump head-discharge relationship in the solution of transient pipe flow by the method of characteristics (MOC) is discussed. It was found that the steady-state pump head-discharge curve was not accurate enough to support the solution of unsteady pipe flow application by the MOC.