介质粘度对泵作透平时性能换算影响的研究

发布时间：2018-05-10 21:44

本文选题：离心泵 + 液力透平　；参考：《兰州理工大学》2017年硕士论文

【摘要】：能源是推动社会经济发展的主要动力,同时也是可持续发展的有力保证。目前人类面临的突出问题主要是能源短缺与社会经济发展之间的矛盾,因此合理的应用能源是目前面临的重要问题。而液力透平作为一种能量回收设备,能够对流体介质中的动能进行提取,在生产实践中具有重要的现实意义。自发现泵可以反转作液力透平使用以来,国内外的研究学者做了大量这方面的研究,但是总体来说,以泵与液力透平之间性能换算系数方面的研究居多。这些研究的介质大多都是清水,或者是将粘度较小的介质当作无粘流体处理。但是在石油化工等行业中,输送的介质大多都是粘度较大的介质,这无疑会对流体机械的性能产生较大的影响。因此,本文开展有关介质粘度对透平性能的影响就很有必要。这也为今后更好地研究液力透平提供一定的依据。本文以5台液力透平、5种不同粘度的介质为研究对象,采用CFD方法进行数值模拟,以此来分析介质粘度对液力透平性能的影响。本文主要的研究内容与研究结果如下:1.液力透平外特性。通过粘性介质下液力透平的水力效率、压头与流量关系曲线可发现,随介质粘度的增大,液力透平的水力效率明显下降,液力透平的压头则随介质粘度的增大下降不明显。2.换算系数。将粘性介质最优效率点时透平的流量、压头与泵在清水介质最优工况时的流量、扬程作比即可得到两者之间的换算系数。通过分析可发现随着介质粘度的增大,流量、扬程/压头换算系数均增大;而当介质粘度相同时,流量、扬程/压头换算系数随比转速的增大则大体呈下降趋势。3.液力透平的内流场。液力透平在蜗壳进口处的压力最高,流体沿着蜗壳进口到叶轮出口的整个过程中,液力透平的静压值逐渐降低。另外当液力透平在小流量工况下运行时,流道内的速度较小,流动较为平稳,此时液力透平内部只存在少量的涡。随流量的增大,叶轮流道中涡的尺度增大,且涡的位置逐渐由叶片背面向叶片工作面转移。
[Abstract]:Energy is the main driving force to promote social and economic development, but also a strong guarantee of sustainable development. At present, the main problem facing mankind is the contradiction between energy shortage and social and economic development, so the rational application of energy is an important problem. As a kind of energy recovery equipment, hydraulic turbine can extract kinetic energy from fluid medium, which has important practical significance in production practice. Since it was discovered that the pump can be used as a hydraulic turbine, researchers at home and abroad have done a lot of research in this field, but generally speaking, the research on the conversion coefficient between pump and hydraulic turbine is the most. Most of the media studied are clear water, or the medium with low viscosity is treated as non-viscous fluid. However, in the petrochemical industry, most of the transport media are viscosity medium, which will undoubtedly have a greater impact on the performance of fluid machinery. Therefore, it is necessary to study the effect of medium viscosity on turbine performance in this paper. This also provides a certain basis for better study of hydraulic turbine in the future. In this paper, five kinds of hydraulic turbine and five different viscosity media are taken as the research object. The CFD method is used to simulate the effect of the medium viscosity on the hydraulic turbine performance. The main contents and results of this paper are as follows: 1. External characteristics of hydraulic turbine. Through the hydraulic efficiency of hydraulic turbine in viscous medium, the relation curve between pressure head and flow rate can be found that the hydraulic efficiency of hydraulic turbine decreases obviously with the increase of medium viscosity, while the hydraulic head of hydraulic turbine does not decrease obviously with the increase of medium viscosity. Conversion factor. The conversion coefficient can be obtained by comparing the flow rate of turbine at the optimal efficiency point of viscous medium, the flow rate of pressure head and pump in the optimal working condition of clear water medium and the ratio of head to head. Through analysis, it can be found that with the increase of medium viscosity, the conversion coefficient of head / head increases with the increase of medium viscosity, but when the viscosity of medium is the same, the conversion coefficient of head / head decreases with the increase of specific speed. The internal flow field of a hydraulic turbine. The pressure of the hydraulic turbine is the highest at the inlet of the volute, and the hydrostatic pressure of the turbine decreases gradually during the whole process from the inlet of the volute to the outlet of the impeller. In addition, when the hydraulic turbine is running under the condition of small flow rate, the velocity in the runner is smaller and the flow is more stable. At this time, there are only a few vortices in the hydraulic turbine. With the increase of the flow rate, the scale of the vortex in the impeller passage increases, and the position of the vortex gradually shifts from the back of the blade to the blade face.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ051.21

【参考文献】