【摘要】：由于河川流量年間變化很大，近年多有運行單位提出貫流式水輪機除了通常的協(xié)聯(lián)工況以外，希望改善部分負(fù)荷的性能亦即擴大運轉(zhuǎn)范圍的要求。就此本論文對應(yīng)變落差·變流量特性的要求，基于CFD技術(shù)對于水輪機汽蝕性能及水壓脈動進行了分析研究。 論文中首先對五葉片貫流式水輪機進行了模型試驗結(jié)果與CFD數(shù)值實驗結(jié)果的比對，顯示了CFD預(yù)測的單位流量QDH、單位轉(zhuǎn)速nDH關(guān)系與模型試驗結(jié)果吻合較好，提示了應(yīng)用CFD技術(shù)也能夠達到研究要求，論文以下研究采用CFD數(shù)值計算結(jié)果進行。本論文首先對四葉片貫流式水輪機進行了全流道定常流動數(shù)值解析，提出了轉(zhuǎn)輪葉片出口與尾水管流動的協(xié)聯(lián)優(yōu)化理念及方法，定量地找到了研究對象轉(zhuǎn)輪葉片出口與尾水管協(xié)聯(lián)運行的特性系數(shù)。研究結(jié)果為水輪機優(yōu)化設(shè)計、協(xié)聯(lián)工況預(yù)測提供了技術(shù)支持，也為水輪機非定常流動數(shù)值計算提供了較好的計算初始環(huán)境。 論文對三、四、五葉片貫流式水輪機的小流量工況、協(xié)聯(lián)工況、大流量工況進行了全流道非定常數(shù)值仿真計算，結(jié)果表明：三、四、五葉片貫流式水輪機由水輪機入口至水輪機出口能量場傳遞清晰有序，能量轉(zhuǎn)換合理。葉片由輪轂至輪緣表面壓力分布進行分析表明，三種葉片水輪機轉(zhuǎn)輪入口負(fù)壓面輪緣處有局部壓力低下，有可能產(chǎn)生局部汽蝕，，需提請注意轉(zhuǎn)輪優(yōu)化設(shè)計時應(yīng)對輪緣處入口角度進行合理的馴化。 論文中重點檢測了兩個境界面流動的壓力脈動程度：活動導(dǎo)葉出口與轉(zhuǎn)輪入口界面，協(xié)聯(lián)、大流量、小流量工況，三、四、五葉片壓力脈動由輪轂至輪緣分布有規(guī)律性，脈動值在要求范圍之下，發(fā)生不穩(wěn)定現(xiàn)象可能性較少。轉(zhuǎn)輪出口與尾水管入口界面，三葉片水輪機尾水管中心處表現(xiàn)出較大的壓力變化，尾水圓錐管及擴大管中的流動也受到了影響，運行穩(wěn)定性指數(shù)降低。 本論文研究結(jié)果可見，所開發(fā)的三、四、五葉片燈泡貫流式水輪機總體性能理想，特別是希望改善性能的偏工況，汽蝕及穩(wěn)定性良好。三葉片水輪機轉(zhuǎn)輪葉片數(shù)少，葉片之間很難形成葉片通路，因而開發(fā)會遇到困難。本研究的三葉片分析成果可以對其后續(xù)開發(fā)提供切實有效的技術(shù)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.
【學(xué)位授予單位】：華南理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TK733.8

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