不同叶片出口角和转速下海水淡化泵的性能分析

An Analysis of the Performance of the Seawater Desalination Pump in Different Blade Outlet Angles and Rotating Speeds

为研究叶片出口角及变频调速对海水淡化泵性能的影响,采用计算流体力学软件CFX对不同叶片出口角和转速下的海水淡化泵进行了数值模拟计算,得出其扬程和效率曲线,并分析了泵内部流场的压力和速度分布。分析结果表明:出口角度增加,扬程逐渐上升,但效率的变化却不明显,叶片出口压力逐渐增加,沿着蜗壳一圈的高压区不断扩大,叶片出口速度逐渐增加。转速从额定转速开始降低时,扬程下降很快,效率在小流量时没有太大变化,在大流量时则不断降低,内部流场的整体压力随着转速的降低而降低,流体的速度也相应地减小。在小流量时,出口角度的增加和转速的增加对效率的影响都不明显,在大流量时,改变出口角度对效率的影响依然影响不大,但降低转速却会让效率曲线变得较平坦。额定工况运行时,泵流体经导叶从侧面流入环形蜗壳,且蜗壳采用中心对称型,从而使流体在蜗壳流道的环形截面以及蜗壳出口沿导叶的一侧形成漩涡。

To study the influence of blade outlet angle and speed regulation method by frequency conversion to the performance of seawater desalination pumps ,this paper adopts the Compute Dynamic software-CFX to conduct a numerical simulation of the flow field of seawater desalination pumps in different blade outlet angles and rotating speeds to obtain the head and efficiency curve .The pressure and velocity distribution in the flow field of pumps are analyzed .The results show that as the blade outlet angle increases ,the head increases gradually but efficiency varies a little .Pressure in blade outlet increases gradually ,high pressure areas expand along the circumferential direction in the volute and velocity in blade outlet also increases gradually .When the rotating speed decreases from the rated rotating speed ,the head decreases rapidly ,efficiency varies little in small flow rates and decreases gradually in large flow rates .The overall pressure in flow field decreases with the decrease in rotating speed and velocity also decreases .In small flow rates ,the increase in blade outlet angles and rotating speeds have no obvious influence on efficiency .In large flow rates ,blade outlet angle also has no obvious influence on efficiency but decreasing rotating the speed would make the efficiency curve relatively flat .Due to the asymmetry layout of the guide vanes ,when the fluid in the pump flow into the side of volute from the guide vane ,some eddies would exist in the volute during the fluid flowing ,and a relatively large eddy exists in one side along the guide vane in the volute .