Numerical analysis on transient characteristics of hydraulic turbine under variable working conditions
SHI Fengxia1,2, YANG Junhu1,2, WANG Xiaohui1,2
1.School of Energy and Power Engineering, Lanzhou University of Technology, Lanzhou, Gansu 730050, China; 2. Key Laboratory of Fluid Machinery and Systems, Gansu Province, Lanzhou, Gansu 730050, China
Abstract：In order to study the transient characteristics of hydraulic turbine under variable working conditions, an unsteady three-dimensional simulation of internal flow field in a hydraulic turbine is performed based on the Reynolds time-averaged governing equations and standard k-ε turbulence model, the characteristics of transient pressure pulsation of internal flow field, radial and axial forces acting on the impeller are presented. The results show that the transient pressure pulsation is more obvious under variable conditions, though static pressure is smaller under low flow conditions, the pressure pulsation amplitude is the largest. The pressure pulsation amplitude is the smallest at best efficiency point, while the amplitude is in between under high flow conditions. The pressure pulsation amplitude in the interface between the impeller and the volute depends on monitoring positions, also a more violent amplitude is found at the volute discharge, a smaller one occurs in the tongue. The pressure pulsation amplitude rises with increasing flow rate. The dominant frequencies of pressure pulsation in the interface, at the inlet and outlet are equal to the blade passing frequency. There are radial and axial thrusts under various operating conditions. The distribution of transient radial force vector is approximately circular, but the transient axial force declines with reducing flow rate or vice versa and exhibits a nearly periodic vibration pattern with a minimum value.
史凤霞,, 杨军虎,, 王晓晖,. 液力透平变工况瞬态特性的数值分析[J]. 排灌机械工程学报, 2017, 35(3): 200-206.
SHI Fengxia,, YANG Junhu,, WANG Xiaohui,. Numerical analysis on transient characteristics of hydraulic turbine under variable working conditions. Journal of Drainage and Irrigation Machinery Engin, 2017, 35(3): 200-206.
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