水泵水輪機(jī)飛逸與制動(dòng)工況內(nèi)流特性及轉(zhuǎn)輪受力分析
發(fā)布時(shí)間：2018-12-15 02:35
【摘要】：可逆式水泵水輪機(jī)組兼具了發(fā)電及儲(chǔ)能的特點(diǎn),對(duì)調(diào)整電網(wǎng)負(fù)荷起重大作用,尤其對(duì)于西北地區(qū)新能源大發(fā)展中的儲(chǔ)能與改善能源配送結(jié)構(gòu)意義重大。水泵水輪機(jī)在運(yùn)行過程中經(jīng)常會(huì)經(jīng)歷啟動(dòng)、停機(jī)、甩負(fù)荷、飛逸等一系列過渡過程,其中尤以飛逸過渡過程可能引起的破壞性為重。而現(xiàn)今對(duì)飛逸及退出飛逸過程中所經(jīng)歷制動(dòng)工況的研究還不夠深入。因此,通過試驗(yàn)數(shù)據(jù)和數(shù)值模擬計(jì)算,探討研究水泵水輪機(jī)飛逸及制動(dòng)工況的流動(dòng)機(jī)理及轉(zhuǎn)輪受力,對(duì)改善機(jī)組運(yùn)行的穩(wěn)定性意義重大。本文以混流式模型水泵水輪機(jī)為研究對(duì)象,通過數(shù)值模擬與試驗(yàn)結(jié)合的方式研究其飛逸工況以及退出飛逸時(shí)經(jīng)歷的制動(dòng)工況,主要研究?jī)?nèi)容如下:1、利用FLUENT軟件對(duì)混流式水泵水輪機(jī)模型7個(gè)不同開度下的飛逸工況以及小開度11 mm下全特性曲線上包含水輪機(jī)、制動(dòng)、反水泵的7個(gè)工況進(jìn)行全流道數(shù)值模擬,分析并作出單位流量Q11與單位轉(zhuǎn)速n11關(guān)系曲線,通過與試驗(yàn)所得曲線的對(duì)比,確認(rèn)數(shù)值計(jì)算對(duì)這兩個(gè)工況模擬結(jié)果的誤差度在允許范圍內(nèi),可以用于分析。2、對(duì)不同開度下飛逸工況時(shí)的全流道內(nèi)流形態(tài)、壓力脈動(dòng)及轉(zhuǎn)輪受力作出分析,分析開度對(duì)飛逸工況的影響。3、選取較小導(dǎo)葉開度11 mm,對(duì)其制動(dòng)工況進(jìn)行重點(diǎn)探究,著重分析導(dǎo)葉區(qū)的尾跡與壓力脈動(dòng)以及轉(zhuǎn)輪和葉片的受力。通過以上分析研究,得出如下結(jié)論:1、在不同開度下水泵水輪機(jī)進(jìn)入飛逸工況:(1)隨著開度增大到一定值,蝸殼內(nèi)流動(dòng)特性顯著改變,壓力波動(dòng)程度增大,出現(xiàn)高頻脈動(dòng)成分;轉(zhuǎn)輪進(jìn)口沖擊損失使得內(nèi)部高低壓分布的對(duì)稱性被破壞,葉片工作面、背面差值增大。(2)隨著開度的增大,轉(zhuǎn)輪內(nèi)流體速度增加,壓力增大;轉(zhuǎn)輪所受徑向力、軸向力的大小與波動(dòng)幅度隨開度的增大而顯著增加,葉片承受的壓力載荷也普遍增加,流道內(nèi)各監(jiān)測(cè)點(diǎn)的壓力均有不同程度的升高。2、退出飛逸的過渡過程即制動(dòng)工況下:(1)導(dǎo)葉區(qū)充斥著結(jié)構(gòu)大小不一的漩渦,渦系結(jié)構(gòu)的演變及水流沖擊效應(yīng)造成能量的損失,進(jìn)一步轉(zhuǎn)化為紊動(dòng)能,其處壓力脈動(dòng)主頻為葉頻,幅值達(dá)到正常運(yùn)行工況的3倍以上。(2)制動(dòng)工況下轉(zhuǎn)輪所受徑向力呈周期性脈動(dòng),受力方向向一邊傾斜,在飛逸線附近正斜率的制動(dòng)區(qū)域運(yùn)行時(shí)內(nèi)部會(huì)出現(xiàn)旋轉(zhuǎn)失速現(xiàn)象,在轉(zhuǎn)輪出口引發(fā)周期性橫流,對(duì)葉片正、背面產(chǎn)生周期性沖擊,葉片將承受較大的交變應(yīng)力。
[Abstract]:The reversible pump turbine unit has the characteristics of power generation and energy storage, which plays an important role in adjusting the load of power grid, especially for energy storage and improvement of energy distribution structure in the development of new energy sources in Northwest China. A series of transition processes, such as start-up, shutdown, load rejection, flight escape and so on, are often experienced during the operation of the pump turbine, especially the damage caused by the flight escape transition process. However, the research on braking condition in flight escape and exit flight escape is not deep enough. Therefore, by means of experimental data and numerical simulation, it is of great significance to study the flow mechanism of the runaway and braking conditions of the pump turbine and the force acting on the runner, which is of great significance to improve the stability of the unit. This paper takes the Francis model pump turbine as the research object, through the numerical simulation and the test way to study its flight escape condition and the exit flight escape experience braking condition, the main research contents are as follows: 1. Using FLUENT software, the full flow channel numerical simulation is carried out on the full characteristic curves of the Francis pump turbine model under 7 different opening conditions and the low opening of 11 mm, including the turbine, brake and reverse pump. The relationship curve between unit flow rate Q11 and unit rotational speed n11 is analyzed and made. By comparing with the curve obtained from the test, it is confirmed that the error degree of numerical calculation for the simulation results of these two conditions is within the allowable range and can be used for analysis. The flow pattern, pressure pulsation and the force on the runner are analyzed under different opening conditions, and the influence of opening degree on flight escape condition is analyzed. 3. The braking condition is mainly studied by selecting a smaller guide blade opening of 11 mm,. The wake and pressure pulsation in the guide vane region and the stress on the runner and blade are analyzed. Through the above analysis and research, the following conclusions are drawn: 1. Under different opening degrees, the pump turbine enters the flight escape condition: (1) with the opening increasing to a certain value, the flow characteristics in the volute significantly change, and the pressure fluctuation degree increases. High frequency pulsation; The impingement loss at the inlet of the runner causes the symmetry of the internal distribution of high and low pressure to be destroyed, and the difference on the back side of the blade face increases. (2) with the increase of opening, the fluid velocity and pressure in the runner increase; The radial force, the axial force and the fluctuation amplitude of the runner increased significantly with the increase of opening, and the pressure load on the blade increased generally, and the pressure at the monitoring points in the runner increased in varying degrees. 2. In the transient process of exit from flight, that is, under braking conditions: (1) the guide vane region is filled with swirls of different sizes, and the energy loss caused by the evolution of vortex structure and the impact effect of water flow is further transformed into turbulent energy. The main frequency of pressure pulsation is blade frequency, and the amplitude is more than 3 times of the normal operating condition. (2) under braking condition, the radial force of the runner fluctuates periodically, and the direction of the force is inclined to one side. In the braking area with positive slope near the flight escape line, the phenomenon of rotating stall will occur inside, and the periodic transverse flow will occur at the outlet of the runner, which will have a periodic impact on the positive and back of the blade, and the blade will bear larger alternating stress.
【學(xué)位授予單位】：蘭州理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TV136
[Abstract]:The reversible pump turbine unit has the characteristics of power generation and energy storage, which plays an important role in adjusting the load of power grid, especially for energy storage and improvement of energy distribution structure in the development of new energy sources in Northwest China. A series of transition processes, such as start-up, shutdown, load rejection, flight escape and so on, are often experienced during the operation of the pump turbine, especially the damage caused by the flight escape transition process. However, the research on braking condition in flight escape and exit flight escape is not deep enough. Therefore, by means of experimental data and numerical simulation, it is of great significance to study the flow mechanism of the runaway and braking conditions of the pump turbine and the force acting on the runner, which is of great significance to improve the stability of the unit. This paper takes the Francis model pump turbine as the research object, through the numerical simulation and the test way to study its flight escape condition and the exit flight escape experience braking condition, the main research contents are as follows: 1. Using FLUENT software, the full flow channel numerical simulation is carried out on the full characteristic curves of the Francis pump turbine model under 7 different opening conditions and the low opening of 11 mm, including the turbine, brake and reverse pump. The relationship curve between unit flow rate Q11 and unit rotational speed n11 is analyzed and made. By comparing with the curve obtained from the test, it is confirmed that the error degree of numerical calculation for the simulation results of these two conditions is within the allowable range and can be used for analysis. The flow pattern, pressure pulsation and the force on the runner are analyzed under different opening conditions, and the influence of opening degree on flight escape condition is analyzed. 3. The braking condition is mainly studied by selecting a smaller guide blade opening of 11 mm,. The wake and pressure pulsation in the guide vane region and the stress on the runner and blade are analyzed. Through the above analysis and research, the following conclusions are drawn: 1. Under different opening degrees, the pump turbine enters the flight escape condition: (1) with the opening increasing to a certain value, the flow characteristics in the volute significantly change, and the pressure fluctuation degree increases. High frequency pulsation; The impingement loss at the inlet of the runner causes the symmetry of the internal distribution of high and low pressure to be destroyed, and the difference on the back side of the blade face increases. (2) with the increase of opening, the fluid velocity and pressure in the runner increase; The radial force, the axial force and the fluctuation amplitude of the runner increased significantly with the increase of opening, and the pressure load on the blade increased generally, and the pressure at the monitoring points in the runner increased in varying degrees. 2. In the transient process of exit from flight, that is, under braking conditions: (1) the guide vane region is filled with swirls of different sizes, and the energy loss caused by the evolution of vortex structure and the impact effect of water flow is further transformed into turbulent energy. The main frequency of pressure pulsation is blade frequency, and the amplitude is more than 3 times of the normal operating condition. (2) under braking condition, the radial force of the runner fluctuates periodically, and the direction of the force is inclined to one side. In the braking area with positive slope near the flight escape line, the phenomenon of rotating stall will occur inside, and the periodic transverse flow will occur at the outlet of the runner, which will have a periodic impact on the positive and back of the blade, and the blade will bear larger alternating stress.
【學(xué)位授予單位】：蘭州理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TV136
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