【作者】 王焕茂；

【导师】 吴钢； 吴伟章；

【作者基本信息】 华中科技大学 ， 流体机械及工程， 2009， 硕士

【摘要】 水泵水轮机的泵工况特性曲线上存在驼峰区,对泵工况稳定运行造成不利影响。为此水泵水轮机用户在标书和合同上通常对泵工况特性的驼峰区安全裕度做出严格规定。为避免水泵水轮机泵工况运行进入驼峰区,有必要对水泵水轮机泵工况驼峰区特性进行深入研究。本文采用试验研究和数值模拟相结合的方法,对水泵水轮机在驼峰区运行时转轮内部流动以及对机组的影响进行了详细的研究。首先对水泵水轮机模型在泵工况下,取不同导叶开口进行了能量特性和驼峰区压力脉动试验。绘制出水泵水轮机泵工况能量特性曲线,获得了某开口泵工况在不同流量下转轮进口流态的特征,并对驼峰区工况下水泵水轮机蜗壳出口、导叶后转轮前、顶盖和转轮之间、锥管上游和锥管下游、肘管上游和肘管下游7个测点进行了压力脉动试验。而后,应用定常、不可压缩的三维Navier—Stokes方程以及RNG k-ε湍流模型对水泵水轮机泵工况进行了单流道和全流道的三维湍流流场计算与分析,预测了水泵水轮机泵工况的扬程,并与水泵水轮机泵工况在相关开口下的试验值进行了比较。分析结果指出：随着流量减小,水泵水轮机转轮出口靠近上冠处出现的流动分离、从导叶进口流向转轮出口的二次回流、尾水管直锥段靠近转轮进口处出现的正旋流动、转轮叶片负压面出口相对速度大小和方向的变化对水泵水轮机泵工况特性曲线驼峰区的形成有重要影响；若在水泵水轮机水力设计中对导叶和上冠型线进行优化设计、采取措施延迟或减小转轮进口回流的出现和发展,则有可能大大提高水泵水轮机泵工况在驼峰区的性能。本研究成果为进一步研究水泵水轮机泵工况驼峰区特性,改进水泵水轮机泵转轮水力特性提供了依据。更多还原

【Abstract】 On the characteristic curve of the pump mode of pump-turbine there is a hump district,which will affect the stable operation of the pump mode.For this reason,in the pump-turbine tenders and contracts strict rules were usually made for the hump safety margin of the pump mode. In order to avoid the operation in the pump mode of pump-turbine getting into the hump zone,it is necessary to conduct an deep research on this.In this paper,experimental study and numerical simulation were used to make a detailed study for the internal flow of the runner as well as the effects to the unit when pump-turbine was operated at the hump zone.Firstly,energy characteristics and the pressure fluctuation test were made in pump mode of the pump-turbine at different openings of the guide vanes.The energy characteristic curve was drawn in pump mode of the pump-turbine,and the image of the flow pattern at the runner inlet was obtained at a certain guid vanes opening. Pressure fluctuation test was made at the outlet of the volute,between runner and guide vanes,between head cover and runner,at the upstream and downstream of cone, at the upstreamand downstream of the elbow when the pump-turbine was operated at hump zone.Secondly,three-dimensional turbulent flow field calculation and analysis of both one flow passage and whole flow passage in pump mode of pump-turbine were finished by using permanent and incompressible three-dimensional Navier-Stokes equations and the RNG k-εmodel,the delivery lift in pump mode of pump-turbine was predicted and was compared with the test results at relevant guide vanes openings. Analysis pointed out that:with the reducing of flow,the flow separation near the crown of the runner outlet of pump-trbine,the senondary flow from the inlet of guide vanes to the outlet of runner, the positive rotary at the cone of the draft tube near the runner inlet and the size and direction of relative velocity changes at the outlet of the suction surface of the runner blades had an important impact on the formation of the hump zone on the characteristic curve in the pump mode of pump-turbine.If the design of the molded line of the guide vanes and crown is optimized in the design of pump-turbine, at the same time, measures to delay or reduce the appearance and the development of the back flow at the inlet of the runner are taken, the performance in pump mode of the pump-turbine in the hump are may be greatly improved.The results of this study provided a basis for further research of hump area characteristics and improving the hydraulic characteristics of pump-turbine runner in pump mode.更多还原