可逆式水泵水轮机全流道三维非定常数值模拟

发布时间：2018-05-28 01:17

本文选题：水泵水轮机 + 水轮机工况　；参考：《昆明理工大学》2017年硕士论文

【摘要】：抽水蓄能电站水泵水轮机运行中,在水轮机或水泵正常运行、起动、停机、甩负荷等过程中,水压、水流、转速等会产生复杂的变化,并且引起水力振动、机械振动或者各部件的应力变化。为了研究这些现象,采用CFD数值模拟的方法对某蓄能电站水泵水轮机几何建模,采用RNG K-ε模型和SIMPLE算法对水泵水轮机三维全流道的额定流量Qr、0.19Qr、0.473Qr、0.655Qr、0.82Qr及1.2Qr工况以及水泵工况进行全流道三维非定常模拟,得到水泵水轮机内部流场的数据,经过后处理软件的处理来分析对比水泵水轮机内部流场的分布以及变化情况。同时监测蜗壳入口、活动导叶之间、导叶与转轮之间无叶区以及尾水管直锥段和弯肘段压力脉动情况,来分析水泵水轮机各个工况下各部分压力脉动的时域分布以及频域分布。结果表明:水泵水轮机蜗壳内压力呈现由外向内静压力逐级递减分布规律。随之导叶开度增加出力增加,蜗壳的总体压力降低。活动导叶的进口头部均有很强的静压力集中。在0.655Qr流量工况水泵水轮机蜗壳内的周向流动及蜗壳断面上的周向流动流态都非常紊乱有二次回流现象。在0.19Qr、0.473Qr等小流量工况下,在导叶出口形成射流使活动导叶与转轮间无叶区流场恶劣及转轮叶片进水边附近形成涡结构,随负荷增加,活动导叶开度增加,射流减弱,无叶区流场趋于平缓稳定及叶片进水边附近涡结构消失。各个工况下转轮结构表面上,高压红色区域主要集中在转轮叶片进水边的头部,转轮下环进口边及与叶片交接位置附近区域,随着出力增加水轮机过流量加大,高压区由叶片进水边向叶片出水边方向延伸。在偏离最优工况较远时,大的入口冲角将会使水流在转轮叶片头部出现脱流现象,形成涡结构进入转轮叶片间流动,形成叶道涡。在泵工况下,水流的流动方向与水轮机流动方向相反,由转轮叶道甩出的水流直接撞击活动导叶,给活动导叶带来很大的冲击,在导叶的流道中形成强烈的紊流扰动及涡结构,在蜗壳中的水流也特别的紊乱且都伴有二次回流的现象。尾水涡带有多分支相互缠绕,导叶与转轮无叶区受动静干涉高频脉动影响,尾水管区域受尾水涡带低频脉动影响,且各自向上下游传播;各工况下导叶与转轮间无叶区脉动频率不变,各频率幅值随负荷增加而增加。
[Abstract]:In the operation of pump turbine in pumped storage power station, during the normal operation, starting, stopping and load rejection of the turbine or pump, the water pressure, water flow, speed and so on will produce complex changes, and will cause hydraulic vibration. Mechanical vibration or stress variation of components. In order to study these phenomena, the geometric model of pump turbine in a storage power station is modeled by CFD numerical simulation method. The RNG K- 蔚 model and SIMPLE algorithm are used to simulate the rated flow rate QR 0.19QrN 0.473Qrn0.655Qr0.82 Qr and the 1.2Qr working condition of the pump turbine, and the data of the internal flow field of the pump turbine are obtained by using the RNG K- 蔚 model and the SIMPLE algorithm. The distribution and variation of flow field in pump turbine are analyzed and contrasted by post-processing software. At the same time, the pressure pulsation of the inlet of the volute, the active guide vane, the vaneless zone between the guide vane and the runner, as well as the straight cone and elbow section of the draft tube are monitored to analyze the time-domain and frequency-domain distribution of the pressure pulsation in each working condition of the pump turbine. The results show that the internal pressure of the volute of water pump turbine decreases progressively from outside to inside. With the increase of the opening of the guide vane, the total pressure of the volute decreases. The inlet head of the movable guide vane has very strong static pressure concentration. The circumferential flow in the volute of the pump turbine and the circumferential flow on the section of the volute in the 0.655Qr flow condition are very disordered and have secondary reflux phenomenon. Under the condition of small flow rate of 0.19Qr-0.473Qr and so on, the formation of jet at the outlet of the guide vane makes the impeller flow field between the guide vane and the runner worse and the vortex structure formed near the inlet edge of the runner blade. With the increase of load, the opening of the active guide vane increases and the jet decreases. The flow field in the leafless region tends to be stable and the vortex structure near the inlet edge of the blade disappears. On the surface of the runner structure under various working conditions, the high pressure red area is mainly concentrated on the head of the inlet edge of the runner blade, the inlet edge of the lower ring of the runner and the area near the junction position between the runner and the blade. With the increase of the output force, the flow rate of the turbine increases. The high pressure zone extends from the inlet edge of the blade to the outlet edge of the blade. When deviating from the optimal condition, the large inlet angle of attack will cause the flow to deflow at the head of the runner blade, and the vortex structure will flow between the blades of the runner and form the vane vortex. Under the pump condition, the flow direction of the flow is opposite to that of the turbine. The flow from the runner impinges directly on the active guide vane, which brings great impact to the active guide vane, and forms a strong turbulent flow disturbance and vortex structure in the passage of the guide vane. The flow in the volute is also particularly disordered and accompanied by secondary reflux. The tailwater vortex is intertwined with multi-branches, the impeller and guide vane are affected by high frequency pulsation of static and static interference, and the region of draft tube is affected by the low-frequency pulsation of tailwater vortex zone, and propagates to the upstream and downstream respectively. The pulsation frequency of the vaneless region between the guide vane and the runner is constant, and the amplitude of each frequency increases with the increase of the load.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV743;TV734

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