Abstract:Through the establishment of unsteady state process of three-dimensional turbulence numerical simulation, operation characteristics of a new low head pit turbine without governor device were simulated under both the constant and varied runner rotation speed conditions while the inlet pressure was changing periodically. The numerical results show that, with 14% changing of the inlet pressure, the rotation speed change is up to 0.76% and down to 0.21% and the rotation speed fluctuation is 0.25 cycle delayed than that of the inlet pressure. In addition, the flow rate change is up to 8% and 2.5% at the peak value, as well as the efficiency change is down to 10.76% and up to 4%. The va-riation law of turbine torque, flow rate, power and efficiency with time was revealed, and in the variation process of the runner, the transient performance of runner flow in both conditions was analyzed,which can provide rational basis and suggestions for the electrical control equipment selection of a po-wer station.
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