Numerical study on the transient behavior of a radial pump during starting time

Abstract

This paper presents a fast simulation model for predicting the dynamic response of a motor-pump system to startup event. The purpose is to analyze the effect of the impeller acceleration time, the final flow rate and the impeller geometry on the pump transient flow during starting operations. The motor speed and torque variations were predicted by simulating the transient law of the three-phase induction motor by adopting the d-q axes theory. The pump model was built by solving the unsteady flow governing equations with the method of characteristics (MOC). The whole model was validated with available tests from literature. Accordingly, the computation of impeller acceleration, the motor torque, the unsteady pressure and flow rate was made for various starting conditions. The results have revealed that during its starting time, the pump hydraulic transients are well influenced by the motor speed acceleration, the flow inertia and the impeller geometry. Through the analysis of the simulation results, the conclusion was that the accuracy of the present method is reasonable, and it can be used for assisting pumping system design. HIGHLIGHTS Radial pump startup transient was investigated using the method of characteristics (MOC).; Pump fast startup can cause a significant head impact and high torque oscillations.; Startup hydraulic transients are well influenced by the motor acceleration time and the impeller geometry.;

Keywords

• d-q axes theory
• impeller geometry
• induction motor
• method of characteristics
• radial pump
• transient flow