The flow rate measurements are the most difficult part of efficiency tests on prototype hydraulic turbines.Among the numerous flow rate measurement methods,the Winter Kennedy method is preferred for measuring turbine flow rates,since it is convenient,practical and economical.This paper describes efficiency tests on a large 300 MW Francis turbine,with the flow rate measured using the Winter Kennedy method and the Winter Kennedy flow rate coefficient calibrated using the Gibson method.The measured turbine efficiency curve is then compared with the curve provided by the manufacturer.The CFD calculations including the spiral case are then used to analyze the influence with the coefficient K and index n in the Winter Kennedy flow rate formula on the flow rate measurement.The uncertainty values of n and K are a key reason for the differences between the curves obtained from the efficiency test and the curves provided by the manufacturer.
The operating states of hydroelectric generating units vary widely as the operating condition change. The details of the operating characteristics and the operating region partitioning method are discussed for two types of large Francis turbines in the Wanjiazhai Hydropower Plant and two same type large Kaplan turbines in the Shuikou Hydropower Plant. For the Wanjiazhai Hydropower units, the most critical factor affecting the operating stability is the hydraulic pressure fluctuations caused by the vortex rope in the draft tube. For Shuikou Hydropower units, the dynamic stresses as in the piston rod and the blade and the hydraulic thrust on the runner induced by the pressure fluctuations in the flow passage should be used to partition the operating regions. Analyzing the distribution cloud of operating characteristic factors which affects the operating stability in the hill-chart for each individual unit, the forbidden, stable and transient operating regions can be obtained.
WANG ZhengWei1, QIN Liang2, ZENG JiDi3, LIN JiaYang3, YANG JinYi4, CHEN WeiJiang4, LUO YongYao1 & YAN ZongGuo1 1 State Key Laboratory of Hydroscience and Engineering and Department of Thermal Engineering, Tsinghua University, Beijing 100084, China
