贯流式水轮机非定常流动及稳定性研究
发布时间：2019-01-07 15:25
【摘要】：由于河川流量年间变化很大，近年多有运行单位提出贯流式水轮机除了通常的协联工况以外，希望改善部分负荷的性能亦即扩大运转范围的要求。就此本论文对应变落差·变流量特性的要求，基于CFD技术对于水轮机汽蚀性能及水压脉动进行了分析研究。 论文中首先对五叶片贯流式水轮机进行了模型试验结果与CFD数值实验结果的比对，显示了CFD预测的单位流量QDH、单位转速nDH关系与模型试验结果吻合较好，提示了应用CFD技术也能够达到研究要求，论文以下研究采用CFD数值计算结果进行。本论文首先对四叶片贯流式水轮机进行了全流道定常流动数值解析，提出了转轮叶片出口与尾水管流动的协联优化理念及方法，定量地找到了研究对象转轮叶片出口与尾水管协联运行的特性系数。研究结果为水轮机优化设计、协联工况预测提供了技术支持，也为水轮机非定常流动数值计算提供了较好的计算初始环境。 论文对三、四、五叶片贯流式水轮机的小流量工况、协联工况、大流量工况进行了全流道非定常数值仿真计算，结果表明：三、四、五叶片贯流式水轮机由水轮机入口至水轮机出口能量场传递清晰有序，能量转换合理。叶片由轮毂至轮缘表面压力分布进行分析表明，三种叶片水轮机转轮入口负压面轮缘处有局部压力低下，有可能产生局部汽蚀，，需提请注意转轮优化设计时应对轮缘处入口角度进行合理的驯化。 论文中重点检测了两个境界面流动的压力脉动程度：活动导叶出口与转轮入口界面，协联、大流量、小流量工况，三、四、五叶片压力脉动由轮毂至轮缘分布有规律性，脉动值在要求范围之下，发生不稳定现象可能性较少。转轮出口与尾水管入口界面，三叶片水轮机尾水管中心处表现出较大的压力变化，尾水圆锥管及扩大管中的流动也受到了影响，运行稳定性指数降低。 本论文研究结果可见，所开发的三、四、五叶片灯泡贯流式水轮机总体性能理想，特别是希望改善性能的偏工况，汽蚀及稳定性良好。三叶片水轮机转轮叶片数少，叶片之间很难形成叶片通路，因而开发会遇到困难。本研究的三叶片分析成果可以对其后续开发提供切实有效的技术支持。
[Abstract]:Due to the great annual variation of river discharge, in recent years, many operating units have proposed that the performance of partial load should be improved, that is, the requirement of expanding the operating range of tubular turbine, in addition to the usual co-operating conditions. In this paper, the performance of turbine cavitation and water pressure pulsation are studied based on CFD technology. In this paper, the model test results of the five-blade tubular turbine are compared with the results of the CFD numerical experiments. The results show that the nDH relation of unit flow rate QDH, unit speed predicted by CFD is in good agreement with the model test results. It is suggested that the application of CFD technology can also meet the requirements of the research. The following research is carried out by CFD numerical calculation results. In this paper, a numerical analysis of the steady flow in the flow channel of a four-blade tubular turbine is carried out, and the idea and method of co-optimization of the runner blade outlet and the draft tube flow are put forward. The characteristic coefficient of cooperation-running of runner blade outlet and draft tube was found quantitatively. The results provide technical support for the optimal design of turbine and the prediction of coconnecting working conditions, and also provide a good initial environment for the numerical calculation of unsteady flow of the turbine. The unsteady numerical simulation of three, four and five blades tubular turbine with three, four and five blades is carried out in this paper. The results show that: 3, 4, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4. The energy field transfer from the turbine inlet to the turbine outlet is clear and orderly, and the energy conversion is reasonable. The analysis of blade pressure distribution from hub to flange shows that the local pressure is low at the inlet negative pressure surface of three kinds of turbine runner, which may cause local cavitation. Attention should be drawn to the reasonable acclimation of the inlet angle at the flange in the optimal design of the runner. In this paper, the pressure pulsation degree of the flow on two boundary surfaces is mainly measured: the interface between the outlet of the active guide vane and the inlet of the runner, the connection, the large flow rate, the small flow condition, and the distribution of the pressure pulsation from the hub to the rim of the wheel is regular. Under the required range of pulsating values, instability is less likely. At the interface between the runner outlet and the inlet of the draft tube, the pressure changes at the center of the draft tube of the three-vane turbine, the flow in the tailing cone tube and the expanded tube is also affected, and the operating stability index is decreased. The results of this paper show that the developed three, four and five vane bulb tubular turbine has ideal overall performance, especially for improving the partial working conditions of performance, and the cavitation and stability are good. Because of the small number of runner blades, it is difficult to form a blade passage between the blades of a three-blade turbine, so it will be difficult to develop. The results of three-blade analysis can provide practical and effective technical support for its further development.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TK733.8
本文编号：2403815
[Abstract]:Due to the great annual variation of river discharge, in recent years, many operating units have proposed that the performance of partial load should be improved, that is, the requirement of expanding the operating range of tubular turbine, in addition to the usual co-operating conditions. In this paper, the performance of turbine cavitation and water pressure pulsation are studied based on CFD technology. In this paper, the model test results of the five-blade tubular turbine are compared with the results of the CFD numerical experiments. The results show that the nDH relation of unit flow rate QDH, unit speed predicted by CFD is in good agreement with the model test results. It is suggested that the application of CFD technology can also meet the requirements of the research. The following research is carried out by CFD numerical calculation results. In this paper, a numerical analysis of the steady flow in the flow channel of a four-blade tubular turbine is carried out, and the idea and method of co-optimization of the runner blade outlet and the draft tube flow are put forward. The characteristic coefficient of cooperation-running of runner blade outlet and draft tube was found quantitatively. The results provide technical support for the optimal design of turbine and the prediction of coconnecting working conditions, and also provide a good initial environment for the numerical calculation of unsteady flow of the turbine. The unsteady numerical simulation of three, four and five blades tubular turbine with three, four and five blades is carried out in this paper. The results show that: 3, 4, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4. The energy field transfer from the turbine inlet to the turbine outlet is clear and orderly, and the energy conversion is reasonable. The analysis of blade pressure distribution from hub to flange shows that the local pressure is low at the inlet negative pressure surface of three kinds of turbine runner, which may cause local cavitation. Attention should be drawn to the reasonable acclimation of the inlet angle at the flange in the optimal design of the runner. In this paper, the pressure pulsation degree of the flow on two boundary surfaces is mainly measured: the interface between the outlet of the active guide vane and the inlet of the runner, the connection, the large flow rate, the small flow condition, and the distribution of the pressure pulsation from the hub to the rim of the wheel is regular. Under the required range of pulsating values, instability is less likely. At the interface between the runner outlet and the inlet of the draft tube, the pressure changes at the center of the draft tube of the three-vane turbine, the flow in the tailing cone tube and the expanded tube is also affected, and the operating stability index is decreased. The results of this paper show that the developed three, four and five vane bulb tubular turbine has ideal overall performance, especially for improving the partial working conditions of performance, and the cavitation and stability are good. Because of the small number of runner blades, it is difficult to form a blade passage between the blades of a three-blade turbine, so it will be difficult to develop. The results of three-blade analysis can provide practical and effective technical support for its further development.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TK733.8
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