混流泵作透平的性能研究

发布时间：2018-01-30 15:07

本文关键词： 混流泵作透平理论分析数值模拟试验研究含沙水　出处：《江苏大学》2017年硕士论文　论文类型：学位论文

【摘要】：大型水电站的建设需要大规模的水坝结构,建设费用高,投资回收周期长,大坝蓄能的水库可能淹没巨大的宝贵农业用地。而小型水电站无此类问题,可提供分散化的发电。尤其是在偏远的乡村和丘陵地带,更加适合发展小型水电站。对于小水电站,采用泵反向运转作为透平发电简单可行。离心泵反转用作透平主要用于小流量、高水头工况,混流泵作透平用于较大流量、中低水头工况。目前,国内外学者对混流泵作透平的研究很少。本课题进行混流泵实型样机反转作透平研究。通过数值模拟、试验比对,结合相关理论研究了混流泵作透平的外特性、内部流动状态、高效设计等。并对比分析了介质为5%浓度的含沙水与清水时混流泵作透平的特性。本课题的主要研究内容及成果如下:1.采用数值模拟与试验方法对比转速为249的混流泵工况及其反转作透平工况的外特性进行了研究,得知混流泵作透平在大流量区域运行较好,运行区间比较宽广;当流量减少时,混流泵作透平的效率不会急剧下降。而在泵工况下,混流泵的效率下降较快。同时较为准确地获得了混流泵作透平的数值模拟方法,为混流泵作透平的后续进一步研究打下了基础。2.采用BladeGen软件对比转速为249的混流泵叶轮进行了改善设计,通过数值模拟,研究了分别改变混流泵作透平叶轮的包角、叶片数以及叶轮外径时,对混流泵作透平性能的影响,获得了不同叶轮几何参数下混流泵作透平的外特性曲线、内部流动状况及水力损失分布规律,分析了叶轮主要几何参数对混流泵作透平性能的影响,可为实际工程运用提供一定的参考。3.针对小水电溪流水质含有泥沙的实际情况,结合固液两相流相关理论,研究了介质分别为5%浓度的含沙水与清水对混流泵作透平的外特性及内部流场分布的影响,得到了混流泵作透平在介质为清水时最高效率点流量下以5%浓度的含沙水为介质运转时,叶轮前盖板内表面上的沙粒体积浓度高于后盖板内表面上的体积浓度,因而对叶轮前盖板内表面,叶片靠近背面的头部区域应重点考虑如何防止沙粒对这些部位的磨蚀;蜗壳第六断面之后的断面体积浓度较入口浓度没有明显变化,但一至五各断面浓度呈明显逐渐增高的趋势,因而在考虑蜗壳内的防磨蚀时,应重点考虑一至五各断面,同时应优先考虑蜗壳中截面附近区域的防磨蚀能力。因此,为混流泵作透平叶轮及蜗壳等的设计提供了一定的参考,具有一定的创新性。
[Abstract]:The construction of large hydropower stations requires a large scale dam structure, high construction cost, long investment recovery cycle, dam storage reservoirs may flood huge valuable agricultural land, while small hydropower stations do not have such problems. Decentralized power generation, especially in remote rural and hilly areas, is more suitable for the development of small hydropower stations. It is simple and feasible to use pump reverse operation as turbine power generation. Centrifugal pump reverse as turbine is mainly used for small flow rate, high water head working condition, mixed flow pump turbine for large flow rate, low water head working condition. At present. There are few researches on turbine of mixed-flow pump at home and abroad. In this paper, a prototype of mixed-flow pump is used to reverse turbine. Through numerical simulation and experimental comparison, combined with relevant theory, the external characteristics of mixed-flow pump as turbine are studied. Internal flow. The characteristics of turbine of mixed flow pump with 5% concentration of sand water and clear water are compared and analyzed. The main contents and results of this research are as follows:. 1. The numerical simulation and test method are used to compare the external characteristics of the mixed flow pump with rotating speed of 249 and its reverse turbine operation. It is known that the mixed flow pump turbine works well in the large flow area and the operation range is relatively wide. When the flow rate is reduced, the turbine efficiency of the mixed flow pump will not decrease sharply, but under the pump condition, the efficiency of the mixed flow pump will decrease more quickly. At the same time, the numerical simulation method of the turbine made by the mixed flow pump is obtained more accurately. It lays the foundation for the further study of the mixed flow pump turbine. 2. The improved design of the impeller of the mixed flow pump is compared with that of the impeller with rotating speed of 249 by using BladeGen software, and the numerical simulation is carried out. The effects of changing the angle of the turbine impeller, the number of blades and the outer diameter of the impeller on the turbine performance of the mixed flow pump are studied, and the external characteristic curves of the mixed flow pump with different impeller geometry parameters are obtained. The internal flow condition and the distribution of hydraulic loss are analyzed. The influence of the main geometric parameters of impeller on the turbine performance of the mixed flow pump is analyzed. It can provide a certain reference for practical application. 3. In view of the actual situation of sediment in the water quality of small hydropower stream, combined with the theory of solid-liquid two-phase flow. The effects of sand water and clear water with 5% concentration on the external characteristics of turbine and the distribution of flow field in the mixed flow pump are studied. The maximum efficiency point flow rate of mixed flow pump as turbine is obtained when 5% concentration of sand water is used as medium when the medium is clear water. The volume concentration of sand on the inner surface of the front cover plate of the impeller is higher than that on the inner surface of the back cover plate, so the inner surface of the front cover plate of the impeller is opposite. The area of the head near the back of the leaf should focus on how to prevent the erosion of these parts by sand particles. The volumetric concentration of the volute after section 6th has no obvious change compared with the inlet concentration, but the concentration of each section in the first to fifth section is increasing gradually, so the abrasion and corrosion resistance in the volute is considered. The first to fifth sections should be considered, and the anti-wear ability of the area near the middle section of the volute should be given priority. Therefore, this paper provides a certain reference for the design of turbine impeller and volute of mixed-flow pump. Have certain innovation.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV734

【参考文献】