本文選題：混流式水輪機 + 水力振動　； 參考：《河北工程大學》2014年碩士論文

【摘要】：作為水電站的核心部件的水輪機組，對水電站的整體性能起著關(guān)鍵性的作用。隨著水輪機組單機容量和裝機尺寸的逐漸增大，水輪機比轉(zhuǎn)速日益提高，水輪機振動問題越來越突出，因而人們對于混流式水輪機的運行穩(wěn)定性越來越重視，其中流場不穩(wěn)定流動現(xiàn)象是引起振動的主要原因之一。利用CFD技術(shù)，對混流式水輪機過流部件內(nèi)部流動進行三維定常及非定常流動分析，可以比較深入地了解水輪機水力振動方面的內(nèi)在機理，這樣對水輪機的綜合水力性能的提高、水輪發(fā)電機組的運行穩(wěn)定性的改善具有非常重要的實際意義。 本文以學校試驗臺的模型水輪機HL160-LJ-25為研究對象，，主要研究內(nèi)容如下： （1）利用三維造型軟件Solidworks和ICEM網(wǎng)格劃分軟件對水輪機的蝸殼、固定導(dǎo)葉、尾水管的過流流道進行實體造型和網(wǎng)格劃分，利用專業(yè)旋轉(zhuǎn)機械軟件Bladegen和Turbogrid對活動導(dǎo)葉和轉(zhuǎn)輪進行實體造型和結(jié)構(gòu)化網(wǎng)格劃分。 （2）采用k-ε湍流模型對水輪機整體內(nèi)部流動進行數(shù)值計算。因為蝸殼和固定導(dǎo)葉造型時放在了一起，所以水輪機整個流道由四個計算域組成，存在三對交界面，兩個不轉(zhuǎn)動計算域的交界面采用General Connection方式連接，不轉(zhuǎn)動的與轉(zhuǎn)動的計算域交界面采用Frozen Rotor Model方式連接，由此對若干工況下水輪機的內(nèi)部流動進行了三維定常湍流計算。研究發(fā)現(xiàn)大流量工況下轉(zhuǎn)輪的內(nèi)部流動特性普遍比小流量工況的流動特性好，最優(yōu)工況附近流動特性最好，與以往傳統(tǒng)認識相符。 （3）以#1小流量工況全流道的三維定常計算結(jié)果作為初始條件，對水輪機進行三維非定常湍流計算，重點分析了活動導(dǎo)葉和轉(zhuǎn)輪之間動靜干涉下的流場和尾水管內(nèi)流場的流動特點。研究發(fā)現(xiàn)由于導(dǎo)葉出流的影響在某固定位置上總是出現(xiàn)壓強最大值和壓強最小值，在不同的時間步下，對于一個固定點，其壓強是隨著轉(zhuǎn)輪的轉(zhuǎn)動在不停地作周期性變化。#1工況下渦帶從轉(zhuǎn)輪出口直至發(fā)育到彎肘段消失，在直錐段呈現(xiàn)比較大的壓力脈動，肘管段的脈動主要集中于肘管的外壁側(cè)，在肘管段的下部直至擴散段壓力脈動很小。分析計算結(jié)果表明，雖然轉(zhuǎn)輪內(nèi)部也存在流動不穩(wěn)定問題，存在壓力分布不理想現(xiàn)象，但壓力脈動振幅很小，且無明顯規(guī)律，有待于今后作更深入研究探討。
[Abstract]:As the core component of hydropower station, hydraulic turbine unit plays a key role in the whole performance of hydropower station. With the increasing of the unit capacity and the size of the turbine unit, the specific speed of the turbine increases day by day, and the vibration problem of the turbine becomes more and more prominent, so people pay more and more attention to the operation stability of the Francis turbine. The unstable flow is one of the main causes of vibration. By using CFD technology, three-dimensional steady and unsteady flow analysis is carried out on the internal flow of the flow passing parts of a Francis turbine. The inherent mechanism of hydraulic vibration of the turbine can be deeply understood, and thus the comprehensive hydraulic performance of the turbine can be improved. It is of great practical significance to improve the operation stability of hydroelectric generating sets. In this paper, the model hydraulic turbine HL160-LJ-25 of the school test bench is taken as the research object. The main research contents are as follows: 1) solid modeling and meshing of turbine volute, fixed guide vane and draft tube flow passage are carried out by using 3D modeling software Solidworks and ICEM mesh division software. The solid modeling and structured meshing of moving guide vane and runner are carried out by using professional rotating machine software Bladegen and Turbogrid. K- 蔚 turbulence model is used to calculate the internal flow of hydraulic turbine. Because the volute and the fixed guide vane are placed together, the whole runner of the turbine is composed of four calculation fields, and there are three pairs of interfaces. The two interfaces in the non-rotating computing field are connected by General Connection. The interface between the non-rotating and rotational computational domain is connected by Frozen Rotor Model mode. Thus, the three-dimensional steady turbulent flow of the turbine is calculated under a number of operating conditions. It is found that the internal flow characteristics of the runner under large flow conditions are generally better than those of small flow conditions, and the flow characteristics near the optimal conditions are the best, which is consistent with the previous traditional understanding. (3) taking the three-dimensional steady calculation results of the whole flow channel in #1 small flow condition as the initial condition, the three-dimensional unsteady turbulent flow calculation of the turbine is carried out. The characteristics of the flow field and the flow field in the draft tube under the dynamic and static interference between the guide vane and the runner are emphatically analyzed. It is found that the maximum and minimum pressure always occur at a fixed position due to the influence of the flow out of the guide vane. At different time steps, for a fixed point, The pressure fluctuates periodically with the rotation of the runner. Under the condition of #1, the vortex band disappears from the runner outlet to the elbow section, showing a relatively large pressure pulsation in the straight cone, and the pulsation of the elbow tube is mainly concentrated on the outside side of the cubital tube. The pressure fluctuation from the lower part of the elbow to the diffusion section is very small. The results of analysis and calculation show that although the flow instability exists in the runner and the pressure distribution is not ideal, the amplitude of pressure pulsation is very small and has no obvious regularity, so it needs to be further studied in the future.
【學位授予單位】：河北工程大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TV734.1;TV136.1

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相關(guān)期刊論文 前2條

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