Numerical simulation on unsteady flow in variable speed constant frequency hydraulic turbine under variable flow condition
In order to study the internal flow field and hydrodynamic characteristics of variable speed constant frequency(VSCF)turbine under the condition of variable flow rate.A numerical simulation for hydrodynamic characteristics of Francis VSCF turbine was established based on STAR-CCM +.The pressure fluctuation characteristics and internal flow state of guide vane and runner under constant flow and sinusoidal flow conditions were obtained,and the process of vortex evolution caused by the change of rotating velocity was visualized.The results show that there was a large-scale vortex at the junction of the draft tube inlet and the runner,which was converged with the decrease of rotational speed,while it gradually broke up,separated and finally dissipated after the increase of rotational speed.And there was eddy current on the suction surface of the blade near the entrance of the impeller channel,and there were two vortex core centers in the draft tube,and the position changed with the rotating speed;the pressure fluctuation in the vaneless space was more intense than the other positions,and the pulsation amplitude increased with the increase of speed and flow rate.The research results can provide basis and reference for the design and engineering appli-cation of VSCF hydraulic turbine.
francis turbinevariable speed constant frequencyvariable flow conditionpressure fluctuationnumerical simula-tion
国家科技期刊平台
NSTL
万方数据
维普
