Study on multi-operating performance optimization and pressure pulsation characteristics of forward-curved impeller used in a pump as turbine

In order to improve the efficiency of high-pressure liquid recovery and utilization in the desalination industry, a forward curved blade turbine in the desalination energy recovery integrated machine is investigated as the research object in this article. The optimization research of the flow components is completed, and the transient pressure pulsation characteristics of the turbine before and after optimization are analyzed. The numerical simulations are performed using Ansys CFX software. The study found that the volute pressure pulsation is mainly affected by the rotor-stator interaction, and its amplitude is proportional to the distance from the impeller. The intensity and range of the pressure fluctuation in the impeller are mainly affected by the flow separation effect, among which the separation vortex and secondary vortex cause low-frequency pulsation in the flow channel. The pressure pulsation amplitude of the optimized geometry is reduced compared with the initial geometry under various operating conditions. The dead water area of the flow field in the impeller flow channel is reduced, and the low work capacity caused by the low pressure on the leading edge pressure surface of the blade under small flow conditions is improved. This enhancement is conducive to increasing the pressure bearing capacity of the blade and reducing the possibility of blade damage due to uneven force. The optimization contributes to the stable operation of the turbine.