發(fā)布時(shí)間：2018-06-15 23:24

  本文選題：混流式水輪機(jī) + 數(shù)值模擬�。� 參考：《哈爾濱工業(yè)大學(xué)》2014年碩士論文

【摘要】：我國水力資源豐富，但近年來森林的砍伐與植被的破壞導(dǎo)致河流含沙量增大，，對(duì)水輪機(jī)過流部件造成嚴(yán)重磨損。雖然水電站已采取一定的補(bǔ)救措施，但水輪機(jī)的性能仍受到一定影響，水輪機(jī)效率嚴(yán)重下降，電站運(yùn)行成本增加，經(jīng)濟(jì)效益下降。導(dǎo)致水輪機(jī)磨損的因素有多種，但設(shè)計(jì)階段未能充分考慮泥沙顆粒的影響是造成在運(yùn)行電站磨損的一個(gè)主要原因，因此，對(duì)于泥沙磨損的研究具有明確的理論意義和實(shí)際意義。 本文基于N-S方程分別以清水和含沙水為介質(zhì)對(duì)高比轉(zhuǎn)速混流式水輪機(jī)進(jìn)行全流道數(shù)值模擬，分析內(nèi)部流動(dòng)特性，掌握泥沙顆粒對(duì)過流部件的磨蝕規(guī)律。在清水工況下水輪機(jī)內(nèi)部的流動(dòng)特性較好，而含沙工況下水輪機(jī)效率下降明顯。為研究泥沙顆粒對(duì)水輪機(jī)性能影響，采取單一變量法。在流量和泥沙顆粒直徑不變時(shí)，隨著泥沙體積分?jǐn)?shù)的增大過流部件的磨損加劇且不成線性變化，泥沙體積分?jǐn)?shù)增大一定數(shù)值之后，磨損量劇增。在流量與泥沙體積分?jǐn)?shù)不變的情況下，泥沙顆粒直徑的改變對(duì)過流部件磨損不能簡(jiǎn)單定量分析，模擬結(jié)果發(fā)現(xiàn)泥沙顆粒直徑越小其與水的相對(duì)速度越小，即此時(shí)泥沙顆粒以更高的速度沖擊材料表面，另外，隨著泥沙粒徑的減小，顆粒的慣性作用降低，對(duì)過流部件上部位置的沖擊更加劇烈，加劇了該區(qū)域的磨損程度，而且磨損更呈現(xiàn)出對(duì)稱性，而大直徑顆粒對(duì)轉(zhuǎn)輪、導(dǎo)葉等靠下位置的局部磨損更嚴(yán)重。當(dāng)泥沙特性不變時(shí)，流量自小到大改變對(duì)應(yīng)于河流自枯水期向豐水期過渡，對(duì)于同一臺(tái)水輪機(jī)，流量增大則過機(jī)流速增加，水輪機(jī)磨損會(huì)加劇。計(jì)算結(jié)果表明：不論是何種工況下，水輪機(jī)的磨損位置主要是蝸殼底部、蝸殼鼻端、座環(huán)、固定導(dǎo)葉和活動(dòng)導(dǎo)葉頭部、轉(zhuǎn)輪進(jìn)出水邊及葉片下側(cè)三角區(qū)。 將數(shù)值模擬結(jié)果與電站運(yùn)行一個(gè)汛期的過流部件磨損情況對(duì)比，計(jì)算結(jié)果符合實(shí)際磨損情況，說明ANSYS CFX軟件可以很好的模擬水輪機(jī)內(nèi)部流動(dòng)。通過模擬結(jié)果可以為水輪機(jī)的葉型的優(yōu)化及電站尋求更好的抗磨措施提供有效的幫助。
[Abstract]:China is rich in hydraulic resources, but in recent years, deforestation and vegetation destruction have led to the increase of sediment content in rivers, which has caused serious wear and tear to the hydraulic turbine overflow parts. Although some remedial measures have been taken for hydropower stations, the performance of hydraulic turbines is still affected to a certain extent, the efficiency of turbines is seriously reduced, the operating costs of power stations are increased, and the economic benefits are decreased. There are many factors leading to turbine wear, but the influence of sediment particles is one of the main causes in the design stage. Therefore, the research on sediment wear has clear theoretical and practical significance. Based on the N-S equation, the full-channel numerical simulation of Francis turbine with high specific speed is carried out using water and sand water as the medium, the internal flow characteristics are analyzed, and the erosion law of the passing parts of sediment particles is grasped. The flow characteristics of the turbine are better under the condition of clear water, but the efficiency of the turbine decreases obviously under the condition of sand content. In order to study the effect of sediment particles on turbine performance, a single variable method was adopted. When the flow rate and sediment particle diameter are constant, the wear of the flow parts increases with the increase of sediment volume fraction and does not change linearly. When the sediment volume fraction increases by a certain value, the wear rate increases sharply. Under the condition of constant flow rate and sediment volume fraction, the change of sediment particle diameter can not simply quantitatively analyze the wear of the flow passing parts. The simulation results show that the smaller the sediment particle diameter is, the smaller the relative velocity between sediment particle diameter and water is. In addition, with the decrease of sediment particle size, the inertial action of the particle decreases, and the impact on the upper position of the overflowing component becomes more intense, which intensifies the wear degree of the area. Moreover, the wear is more symmetrical, and the local wear of large diameter particles is more serious on the lower position of runner and guide vane. When the sediment characteristics are not changed, the flow rate changes from small to large corresponding to the transition from low to high water period. For the same turbine, the flow rate increases and the turbine wear will increase. The results show that the main wear position of the turbine is the bottom of the volute, the nose end of the volute, the seat ring, the head of the fixed guide vane and the active guide vane, the runner entering and leaving the water edge and the triangle area of the lower side of the blade. The numerical simulation results are compared with the wear of the overcurrent parts in a flood season of the power station. The calculated results are in line with the actual wear situation, which shows that the ANSYS CFX software can simulate the internal flow of the turbine well. The simulation results can provide effective help for the optimization of turbine blade shape and the seeking of better anti-wear measures for the power station.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TK733.1

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本文編號(hào)：2024103