本文選題：混流式水輪機 + 壓力脈動��； 參考：《哈爾濱工業(yè)大學(xué)》2017年碩士論文

【摘要】：隨著能源工業(yè)的發(fā)展,隨著工藝技術(shù)的日趨成熟,中國水電工業(yè)已進入電網(wǎng)峰值高、機組裝機容量大、集成網(wǎng)絡(luò)化管理的蓬勃發(fā)展時期。目前在建的白鶴灘電站建成后,單機容量將超過百萬千瓦,總裝機容量將位列三峽電站之后,成為國內(nèi)第二大水電站。受運行條件的限制及電網(wǎng)實際需求的不同,混流式水輪機經(jīng)常要在偏離設(shè)計工況下運行,由此引起的運行不穩(wěn)定問題一直是行業(yè)研究的重點課題。作為考核水輪機穩(wěn)定性的重要衡量標準,壓力脈動性能也就成為研究的重點。本課題正是基于白鶴灘電站的模型混流式水輪機,利用數(shù)值模擬的手段,對不同單位轉(zhuǎn)速,不同開度的工況進行非定常數(shù)值模擬,詳細分析內(nèi)部流動機理,得到壓力脈動的特性及其在全流道內(nèi)的傳播規(guī)律,并得到轉(zhuǎn)速及開度的變化對壓力脈動的具體影響,主要研究內(nèi)容如下:(1)在同一開度(a_0=8.47mm)不同單位轉(zhuǎn)速下,針對不同工況點進行非定常計算,找出各流域內(nèi)壓力脈動的主頻、次頻、二次頻等,對各頻率相關(guān)性進行分析,研究各流域內(nèi)壓力脈動特性及沿流向的傳播規(guī)律,并對比各工況得出轉(zhuǎn)輪轉(zhuǎn)速對壓力脈動幅值及頻率的影響規(guī)律;(2)在同一單位轉(zhuǎn)速(n_(11)=5 8.8 r/min)下,改變活動導(dǎo)葉開度,針對不同工況點進行非定常數(shù)值模擬,得出各流域壓力脈動特性,并得到壓力脈動沿全流道進行傳播的變化規(guī)律,探究導(dǎo)葉開度對壓力脈動峰值及主要頻率的影響規(guī)律,結(jié)合計算得到的速度場、壓力場及渦量場,分析各流域內(nèi)的壓力脈動源的產(chǎn)生機理。(3)在變流量工況下,得到各流域內(nèi)壓力脈動連續(xù)變化趨勢,結(jié)合所得到流場分析該工況下的流動狀態(tài),并與定流量工況進行比較,分析壓力脈動特性的異同。本文的研究結(jié)果表明,壓力脈動主要頻率受導(dǎo)葉開度及轉(zhuǎn)輪轉(zhuǎn)速的影響,在全流道內(nèi)既向上游傳播又向下游傳播,并沿途衰減或增加。小開度時,隨轉(zhuǎn)速增加,壓力脈動幅值整體增加。在小開度下,低轉(zhuǎn)速及高轉(zhuǎn)速時表現(xiàn)為尾水渦帶的低頻壓力脈動,中轉(zhuǎn)速下表現(xiàn)為無葉區(qū)轉(zhuǎn)輪葉片通過頻率。而在大開度下,壓力脈動的幅值整體減小,這表明開度減小,壓力脈動特性逐漸明顯,脈動程度更劇烈。在變流量下,流量的持續(xù)增加使全流道內(nèi)壓力脈動的振幅發(fā)生巨大改變,顯著高于同開度同轉(zhuǎn)速下的定流量工況。
[Abstract]:With the development of energy industry and the maturation of technology, Chinese hydropower industry has entered the vigorous development period of high peak value of power grid, large installed capacity of unit and integrated network management. After the construction of Baihetan Hydropower Station currently under construction, the single unit capacity will exceed one million kilowatts, and the total installed capacity will rank behind the three Gorges Power Station and become the second largest hydropower station in China. Due to the limitation of operation conditions and the difference of actual demand of power grid, Francis turbine often has to operate in deviation from the design condition. The operation instability caused by this problem has always been a key topic in industry research. As an important measure of turbine stability, pressure pulsation performance has become the focus of research. This subject is based on the model Francis turbine of Baihetan Hydropower Station. By means of numerical simulation, the unsteady numerical simulation of different unit rotational speed and different opening is carried out, and the internal flow mechanism is analyzed in detail. The characteristics of pressure pulsation and its propagation in the whole channel are obtained, and the specific effects of the changes of rotational speed and opening degree on the pressure fluctuation are obtained. The main research contents are as follows: 1) at the same opening degree, 0 / 0 / 8.47mm / unit rotating speed. According to the unsteady calculation of different working conditions, the main frequency, secondary frequency and secondary frequency of pressure pulsation in each watershed are found out. The correlation of each frequency is analyzed, and the characteristics of pressure pulsation and the propagation law along the flow direction are studied. The influence of runner speed on the amplitude and frequency of pressure pulsation is obtained by comparing the different working conditions. The unsteady numerical simulation is carried out at different operating conditions by changing the opening of the active guide vane under the same unit rotational speed (n / v) and 58.8 r / min. The characteristics of pressure pulsation in each basin are obtained, and the variation law of pressure pulsation propagating along the whole channel is obtained. The influence of guide vane opening on the peak value and main frequency of pressure pulsation is explored, and the velocity field, pressure field and vorticity field obtained by calculation are combined with the calculated velocity field, pressure field and vorticity field. The generation mechanism of pressure pulsation source in each watershed is analyzed. Under variable flow condition, the continuous variation trend of pressure pulsation in each watershed is obtained. The flow state under this condition is analyzed in combination with the obtained flow field, and compared with the constant flow condition. The characteristics of pressure fluctuation are analyzed. The results show that the main frequency of the pressure pulsation is affected by the speed of the guide vane and the rotating speed of the runner, which propagates both upstream and downstream in the whole channel, and attenuates or increases along the way. When the opening is small, the amplitude of pressure pulsation increases with the increase of rotational speed. At low speed and high speed, the low frequency pressure pulsation of tail water vortex band is observed at low opening and the passing frequency of impeller blade at middle speed. However, the amplitude of the pressure pulsation decreases at large opening, which indicates that the opening decreases, the pressure fluctuation becomes more obvious and the pulsation becomes more intense. Under the condition of variable flow rate, the amplitude of pressure pulsation in the whole channel is greatly changed with the continuous increase of flow rate, which is significantly higher than the constant flow condition with the same opening degree and the same speed.
【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】：2017
【分類號】：TV734.1

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本文編號：1964700