可调导叶对低扬程泵装置水力性能影响的数值计算研究

发布时间：2018-08-30 16:49

【摘要】：低扬程泵站在我国跨流域调水、水环境改善、城市防洪等方面发挥着重要作用。泵装置效率取决于其各组成部分的效率及相互之间连接的顺畅度。导叶在泵装置中上承叶轮,下接出水流道。水泵叶轮出口设置导叶的初衷是将水流的旋转动能转化为压能,从而减小水力损失。当前导叶都是不可调节的,导叶进口安放角是按设计工况下叶轮的出口水流速度三角形确定的。导叶的出口安放角的设计目标应是使得导叶出口获得使出水流道水力性能最优的最优环量,最优环量与流量有关。当工况改变后,叶轮的出口水流速度三角形和出水流道所对应的最优环量都会发生改变,此时导叶的进出口安放角不可调节,水力损失将会增大,泵装置效率下降。本文提出调节导叶进出口安放角以提高泵装置效率的方法。针对导叶进出口安放角对泵装置水力性能的影响的研究,本文的研究工作主要有以下内容:1、对国内外的轴流泵后置导叶的研究成果进行了总结分析,明确了研究导叶进、出口安放角对泵装置水力性能影响的目的、意义和主要研究内容;同时总结分析了数值模拟的发展现状,明确了本文的研究方法及其可行性。2、对轴流泵泵装置进行实体建模以及网格剖分,并对多个不同网格数的轴流泵泵装置模型模拟计算,进行网格的无关性分析,选择数值分析网格数量,以保证其对轴流泵泵装置性能计算结果无影响。在此基础上,运用CFD计算软件对不同方案进行计算,并对模拟结果加以分析与研究。3、提出导叶叶片整体调节的方法,在不同工况点下进行模拟计算。当导叶固定不动时,流量为0.8Qd、0.9Qd、1.0Qd、1.1Qd及1.2Qd时所对应的泵装置效率分别为72.06%、75.33%、74.96%、65.59%及38.84%,导叶整体调节时,不同流量下所能达到的最优效率为74.02%、75.81%、74.96%、66.20%及43.24%,均有所提升;可见,导叶整体调节对提高泵装置效率有所帮助。4、以0.8Qd与1.2Qd为例,分别分析小流量与大流量时导叶出口安放角对出水流道水力性能的影响,提出分部调节导叶的构想,并对其进行计算,得出结论:小流量时,不同调节方案对泵装置水力性能的影响较大。对于最优泵装置效率,整体调节时比固定导叶提高了 1.96%,分部调节又比整体导叶提高了 1.16%;大流量时,整体调节对泵装置水力性能的提升影响较大,泵装置效率比固定导叶时提升了 4.4%,分部调节与整体调节相比影响较小,泵装置效率仅提高了 0.18%。
[Abstract]:Low-lift pumping stations play an important role in water transfer, water environment improvement and urban flood control in China. Pump efficiency depends on the efficiency of each component and the smoothness of connection. The guide vane is connected to the upper impeller in the pump device and the outlet passage to the bottom. The original intention of setting the guide vane at the outlet of the pump impeller is to convert the rotational kinetic energy of the water flow into the pressure energy, so as to reduce the hydraulic loss. At present, the guide vane is unadjustable, and the inlet angle of guide vane is determined according to the flow velocity triangle at the outlet of the impeller under the design condition. The design goal of the outlet placement angle of the guide vane should be to obtain the optimal ring quantity of the outlet vane to make the hydraulic performance of the outlet passage optimal, and the optimal ring quantity is related to the flow rate. When the working condition is changed, the flow velocity triangle at the outlet of the impeller and the optimal annular volume corresponding to the outlet passage will change. At this time, the inlet and outlet angle of the guide vane cannot be adjusted, the hydraulic loss will increase, and the efficiency of the pump device will decrease. This paper presents a method to improve the efficiency of pump device by adjusting the inlet and outlet angle of guide vane. In view of the research on the influence of inlet and outlet angle of guide vane on hydraulic performance of pump unit, the main research work of this paper is as follows: 1. The research results of rear guide vane of axial flow pump at home and abroad are summarized and analyzed, and the research on guide vane is made clear. The purpose, significance and main research contents of the effect of outlet placement angle on hydraulic performance of pump unit are summarized and analyzed, and the development status of numerical simulation is summarized and analyzed. The research method and feasibility of this paper are defined. 2. The solid modeling and mesh generation of the axial flow pump device are carried out, and the model simulation of many different grid numbers of the axial flow pump device is carried out, and the mesh independence analysis is carried out. The number of numerical analysis meshes is chosen to ensure that it has no effect on the performance calculation results of axial pump device. On this basis, the different schemes are calculated by using CFD software, and the simulation results are analyzed and studied. Finally, the method of integral adjustment of the guide vane is put forward, and the simulation calculation is carried out at different working conditions. When the guide vane is fixed, the pump device efficiency corresponding to the flow rate of 0.8QdN 0.9QdN 1.0QdU 1.1Qd and 1.2Qd is 72.060.30 / 75.33and 74.9665.59% and 38.84 respectively. When the guide vane is adjusted as a whole, the optimum efficiency under different flow rates is 74.022.81g / 74.96 / 66.20% and 43.2445%, respectively. The integral adjustment of guide vane is helpful to improve the efficiency of pump unit. Taking 0.8Qd and 1.2Qd as examples, the influence of outlet angle of guide vane on the hydraulic performance of outlet passage is analyzed respectively with small flow rate and large flow rate, and the conception of partial regulating guide vane is put forward. It is concluded that when the flow rate is small, different regulation schemes have great influence on hydraulic performance of pump unit. For the optimal pump unit efficiency, the integral adjustment increases 1.96% compared with the fixed guide vane, and the partial adjustment increases 1.16% compared with the integral guide vane, and when the flow rate is large, the integral regulation has a greater influence on the hydraulic performance of the pump device. Compared with the fixed guide vane, the efficiency of the pump device is increased by 4.4 steps, the effect of the partial adjustment is less than that of the whole regulation, and the efficiency of the pump device is only increased by 0.18.
【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV136.2

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