本文選題：混流式水輪機　切入點：壓力脈動　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)及混流式水輪機設(shè)計與制造技術(shù)的逐步提高，混流式水輪機逐漸向著中比轉(zhuǎn)數(shù)、大功率方向發(fā)展，對機組的穩(wěn)定、安全運行有著重要影響的壓力脈動問題已經(jīng)得到廣大學(xué)者的重視。本文針對尾水管渦帶產(chǎn)生的壓力脈動問題，，采用瞬態(tài)全流道數(shù)值模擬方法對壓力脈動在尾水管處的規(guī)律進行分析，并采用部分流道的模擬得出壓力脈動的成分和來源。 為了實現(xiàn)上述目的，本文對中比轉(zhuǎn)數(shù)模型水輪機4個導(dǎo)葉開度工況的內(nèi)部流場進行了數(shù)值模擬，通過定常數(shù)值模擬研究水力特性情況，驗證數(shù)值計算的準確性和流場各參數(shù)的分布情況，通過非定常數(shù)值模擬得到水輪機壓力脈動隨時間的變化，分析混流式水輪機的壓力脈動在各區(qū)域的頻率分布，研究各主要脈動頻率成分原因。具體的研究內(nèi)容包括以下幾個方面： 首先，采用定常方法對小開度、最優(yōu)開度、和兩個大開度等4個工況下水輪機內(nèi)部流場進行了數(shù)值模擬，研究各工況流動情況，分析流動狀態(tài)產(chǎn)生的不穩(wěn)定原因，研究各個工況主要外特性和流場中的流動變化規(guī)律，得到各工況的水力效率等關(guān)鍵信息。 其次，對各開度工況進行瞬態(tài)的全流道數(shù)值模擬研究，獲得了流道內(nèi)各部件所布測點的壓力脈動數(shù)據(jù)。為了更好的分析壓力脈動能量分布，采用快速傅里葉變換(FFT)方法對得到的壓力脈動進行處理，將脈動的時域信息轉(zhuǎn)化到頻域上。研究各測點在頻域上的共有特性，分析尾水管主要頻率壓力脈動的是由尾水渦帶的旋轉(zhuǎn)運動產(chǎn)生的。 再次，在研究部分流道壓力脈動時，對各開度的工況的無蝸殼流道和無固定導(dǎo)葉流道進行數(shù)值模擬研究，獲得各測點的壓力脈動值，并對其進行FFT方法處理，將時域的脈動信息轉(zhuǎn)換到頻譜圖上，分析各區(qū)域的主要脈動頻率，與全流道的各區(qū)域的主要頻率對比，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。
[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)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TK733.1

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本文編號：1709017