發(fā)布時(shí)間：2018-04-04 07:44

  本文選題：混流式水輪機(jī)　切入點(diǎn)：壓力脈動(dòng)　出處：《哈爾濱工業(yè)大學(xué)》2014年碩士論文

【摘要】：隨著水力資源開發(fā)及混流式水輪機(jī)設(shè)計(jì)與制造技術(shù)的逐步提高，混流式水輪機(jī)逐漸向著中比轉(zhuǎn)數(shù)、大功率方向發(fā)展，對(duì)機(jī)組的穩(wěn)定、安全運(yùn)行有著重要影響的壓力脈動(dòng)問題已經(jīng)得到廣大學(xué)者的重視。本文針對(duì)尾水管渦帶產(chǎn)生的壓力脈動(dòng)問題，，采用瞬態(tài)全流道數(shù)值模擬方法對(duì)壓力脈動(dòng)在尾水管處的規(guī)律進(jìn)行分析，并采用部分流道的模擬得出壓力脈動(dòng)的成分和來(lái)源。 為了實(shí)現(xiàn)上述目的，本文對(duì)中比轉(zhuǎn)數(shù)模型水輪機(jī)4個(gè)導(dǎo)葉開度工況的內(nèi)部流場(chǎng)進(jìn)行了數(shù)值模擬，通過(guò)定常數(shù)值模擬研究水力特性情況，驗(yàn)證數(shù)值計(jì)算的準(zhǔn)確性和流場(chǎng)各參數(shù)的分布情況，通過(guò)非定常數(shù)值模擬得到水輪機(jī)壓力脈動(dòng)隨時(shí)間的變化，分析混流式水輪機(jī)的壓力脈動(dòng)在各區(qū)域的頻率分布，研究各主要脈動(dòng)頻率成分原因。具體的研究?jī)?nèi)容包括以下幾個(gè)方面： 首先，采用定常方法對(duì)小開度、最優(yōu)開度、和兩個(gè)大開度等4個(gè)工況下水輪機(jī)內(nèi)部流場(chǎng)進(jìn)行了數(shù)值模擬，研究各工況流動(dòng)情況，分析流動(dòng)狀態(tài)產(chǎn)生的不穩(wěn)定原因，研究各個(gè)工況主要外特性和流場(chǎng)中的流動(dòng)變化規(guī)律，得到各工況的水力效率等關(guān)鍵信息。 其次，對(duì)各開度工況進(jìn)行瞬態(tài)的全流道數(shù)值模擬研究，獲得了流道內(nèi)各部件所布測(cè)點(diǎn)的壓力脈動(dòng)數(shù)據(jù)。為了更好的分析壓力脈動(dòng)能量分布，采用快速傅里葉變換(FFT)方法對(duì)得到的壓力脈動(dòng)進(jìn)行處理，將脈動(dòng)的時(shí)域信息轉(zhuǎn)化到頻域上。研究各測(cè)點(diǎn)在頻域上的共有特性，分析尾水管主要頻率壓力脈動(dòng)的是由尾水渦帶的旋轉(zhuǎn)運(yùn)動(dòng)產(chǎn)生的。 再次，在研究部分流道壓力脈動(dòng)時(shí)，對(duì)各開度的工況的無(wú)蝸殼流道和無(wú)固定導(dǎo)葉流道進(jìn)行數(shù)值模擬研究，獲得各測(cè)點(diǎn)的壓力脈動(dòng)值，并對(duì)其進(jìn)行FFT方法處理，將時(shí)域的脈動(dòng)信息轉(zhuǎn)換到頻譜圖上，分析各區(qū)域的主要脈動(dòng)頻率，與全流道的各區(qū)域的主要頻率對(duì)比，發(fā)現(xiàn)上游部件的結(jié)構(gòu)在尾水管處將不產(chǎn)生新頻率的壓力脈動(dòng)。
[Abstract]:With the development of hydraulic resources and the gradual improvement of Francis turbine design and manufacture technology, the Francis turbine is developing towards the direction of middle ratio and high power, which is stable to the unit.The problem of pressure fluctuation, which has an important effect on safe operation, has been paid more attention by many scholars.In this paper, the transient full-channel numerical simulation method is used to analyze the law of pressure pulsation in the tail water pipe, and the components and sources of pressure pulsation are obtained by the simulation of some channels.In order to achieve the above purpose, the internal flow field of the four guide vane opening conditions of the medium-specific rotation model hydraulic turbine is numerically simulated in this paper, and the hydraulic characteristics of the turbine are studied by the steady numerical simulation.The accuracy of numerical calculation and the distribution of flow field parameters are verified. The variation of turbine pressure pulsation with time is obtained by unsteady numerical simulation, and the frequency distribution of pressure pulsation in each region of Francis turbine is analyzed.The main pulsating frequency components were studied.The specific research contents include the following aspects:Firstly, the flow field in the turbine under four operating conditions, such as small opening, optimal opening, and two large opening, is numerically simulated by using the steady method, and the flow situation of each working condition is studied, and the reasons for the instability of the flow state are analyzed.The main external characteristics of each working condition and the law of flow variation in the flow field are studied, and the key information such as hydraulic efficiency of each condition is obtained.Secondly, the transient full-channel numerical simulation is carried out to obtain the pressure pulsation data of the measured points in the flow channel.In order to better analyze the energy distribution of pressure fluctuation, the fast Fourier transform (FFT) method is used to deal with the pressure fluctuation, and the time domain information of the pulse is converted to the frequency domain.The common characteristics of each measuring point in frequency domain are studied. It is analyzed that the main frequency pressure pulsation of the draft tube is caused by the rotating motion of the tailwater vortex belt.Thirdly, when the pressure pulsation of some channels is studied, numerical simulation is carried out on the non-volute flow channel and the non-fixed guide vane runner under various open working conditions, and the pressure pulsation values of each measuring point are obtained, and the FFT method is used to deal with the pressure pulsation.The pulsation information in time domain is converted to the spectrum chart, and the main pulsation frequency of each region is analyzed. Compared with the main frequency of each region of the whole channel, it is found that the structure of upstream component will not produce pressure fluctuation of new frequency in the tailwater pipe.
【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)：1709017