后导叶片叶扫掠对轴流泵性能的影响

发布时间：2018-06-21 11:07

本文选题：轴流泵 + 导叶　；参考：《扬州大学》2016年硕士论文

【摘要】：后置导叶是轴流泵中重要的能量回收部件。通过后导叶回收叶轮出口速度环量,将动能转换为压能,不仅可以减小流道水力损失,提高泵及泵装置的水力效率,还有利于泵站的稳定运行,因此,对导叶的优化设计研究具有重要的学术意义和工程应用价值。本文采用CFD数值模拟的方法研究后导叶叶片扫掠不同角度下对轴流泵性能的影响。以减少导叶进、出口及导叶背部的脱流,提高导叶体的环量回收能力为目的,总共进行了六个不同的扫掠方案的导叶设计。通过将导叶片各翼型断面三维坐标值整体顺时针或逆时针旋转一定的角度,得到不同扫掠角度下的导叶叶片,采用标准k-s湍流模型对六种导叶扫掠方案对应的轴流泵段各进行8个流量工况下的定常和非定常的数值模拟计算和比较分析。同时为了进一步研究+16°导叶对轴流泵内部水压力脉动的影响,在叶轮进口、叶轮与导叶间、导叶间及导叶出口四个断面上布置20个监测点进行了压力脉动的监测。首先,对所有监测点在最优工况下进行了监测,然后又采用三个不同的流量工况下对各断面上中间的监测点进行压力脉动监测,得到各监测点压力脉动的时域特性,并经过FFT变换得到频域特性。通过分析比较可知导叶叶片向前扫掠比向后扫掠的效率要高,并且在+16°导叶的轴流泵段效率达到最高,通过模型试验,验证了数值模拟的可靠性。对+16°导叶数值模拟内部流场分析可知,导叶前掠比0°导叶可以更好的减小导叶的脱流情况,尤其在靠近导叶出口轮毂处,能更好的回收速度环量。压力脉动非定常分析可知：不管0°导叶还是+16°导叶,所有监测点的压力脉动频率主要以叶频为主,从轮毂到轮缘的压力脉动幅值,叶轮前是逐渐增大,叶轮与导叶之间、导叶间是先减小后增大,导叶后是先增大后减小,总体上所有监测点在+16°导叶的压力脉动幅值比0°导叶要小,其中在导叶间和导叶出口处压力脉动幅值平均要小40%左右：大流量工况和最优流量工况下,0°导叶除了在导叶出口处监测点压力脉动频率主要以转频为主外,其他的压力脉动频率主要以叶频为主,而+16°导叶各监测点压力脉动频率主要以叶频为主；小流量工况下,在导叶间、导叶出口的监测点压力脉动频率以转频为主,而0°导叶受涡流二次波的影响比+16°导叶要大很多。因此,导叶叶片向前扫掠比导叶叶片向后扫掠性能要好,尤其在+16°时泵段性能达到最佳,+16°导叶在提高泵段性能的同时还能改善靠近导叶出口轮毂处水流流态,回收速度环量,减小泵段内的水压力脉动,尤其是在最优工况或者大流量工况达到最佳。
[Abstract]:Rear guide vane is an important energy recovery component in axial flow pump. Using the back guide vane to recover the velocity loop of impeller outlet and convert kinetic energy into pressure energy can not only reduce the hydraulic loss of flow channel and improve the hydraulic efficiency of pump and pump device, but also benefit the steady operation of pump station. It has important academic significance and engineering application value to study the optimum design of guide vane. In this paper, CFD numerical simulation method is used to study the influence of swept vane on the performance of axial flow pump at different angles. In order to reduce the deflow in and out of the guide vane and the back of the guide vane, and to improve the annular recovery capacity of the guide vane body, six different sweep schemes were carried out for the guide vane design. The guide vane with different sweep angles is obtained by rotating the three dimensional coordinate values of each airfoil section clockwise or counterclockwise. The standard k-s turbulence model is used to simulate and compare the steady and unsteady flow conditions of the axial flow pump sections corresponding to six guide vane sweep schemes. In order to further study the influence of 16 掳guide vane on water pressure pulsation in axial flow pump, 20 monitoring points were arranged on four sections of impeller inlet, impeller and guide vane, guide vane and guide vane outlet. Firstly, all the monitoring points are monitored under the optimal working conditions, and then the pressure pulsation of the monitoring points in the middle of each section is monitored under three different flow conditions, and the time-domain characteristics of the pressure pulsation at each monitoring point are obtained. The characteristic of frequency domain is obtained by FFT transform. Through analysis and comparison, it can be seen that the efficiency of the guide vane is higher than that of backward sweep, and the efficiency of the axial flow pump section of the 16 掳guide vane is the highest. The reliability of the numerical simulation is verified by the model test. The numerical simulation of the flow field of the 16 掳guide vane shows that the guide vane forward sweep is better than the 0 掳guide vane in reducing the decurrent of the guide vane, especially near the hub of the outlet of the guide vane, which can recover the velocity loop better. The unsteady analysis of pressure pulsation shows that the frequency of pressure pulsation is mainly blade frequency at all monitoring points, regardless of the 0 掳guide vane or 16 掳guide vane, and the amplitude of pressure fluctuation from hub to rim increases gradually in front of impeller, between impeller and guide vane. The pressure fluctuation amplitude of all monitoring points at 16 掳guide vane is smaller than that of 0 掳guide vane. The amplitude of pressure pulsation between the guide vane and at the outlet of the guide vane is about 40% smaller on average. Under the condition of large flow rate and optimal flow condition, the pressure pulsation frequency of 0 掳guide vane is mainly rotating frequency, except for the pressure fluctuation frequency at the monitoring point at the outlet of the guide vane. The other pressure pulsation frequencies are mainly blade frequency, while 16 掳guide vane pressure pulsation frequency is mainly blade frequency, under small flow condition, the pressure pulsation frequency of the monitoring point at the outlet of the guide vane is mainly turn frequency under the condition of small flow rate. The influence of secondary eddy current waves on 0 掳guide vane is much greater than that on 16 掳guide vane. Therefore, the sweep performance of the guide vane is better than the backward sweep performance of the guide vane, especially the optimum performance of the pump section at 16 掳. The 16 掳guide vane not only improves the performance of the pump section, but also improves the water flow state near the hub of the outlet wheel of the guide vane. The speed loop is recovered to reduce the water pressure pulsation in the pump section, especially in the optimal working condition or the large flow condition.
【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TV675;TV136.2

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