高速离心泵回流漩涡及空化特性的分析

发布时间：2018-06-04 09:52

本文选题：高速离心泵 + 诱导轮　；参考：《西华大学》2017年硕士论文

【摘要】：高速离心泵是一种小流量高扬程的特殊离心泵,由于高转速的原因,在泵的进口和内部很容易发生回流漩涡和空化空蚀,减少回流漩涡和空化空蚀目前有很多的方法,其中在叶轮前加装孔板和诱导轮的方法,可以有效的抑制回流漩涡和叶轮的空化,从而可以提高高速泵的水力性能。到目前为止未见有学者通过改变孔板的形式来研究其对回流漩涡的影响,本文通过不同形式的孔板抑制装置,分析其对高速泵的进口回流漩涡和空蚀的影响,研究确定出最佳的高速泵进口空化空蚀抑制装置形式。首先,通过单相定常流动分析来确定孔板的几何尺寸,利用正交实验方法确定孔板最佳的厚度、距诱导轮进口的距离和孔径,共设计九个方案。其次,改变孔板前、后倾斜角度,共设计出25种方案,计算分析得到对高速泵水力性能最好的五个方案。最后,对这五种方案进行空化状态下的计算分析,选择出对回流漩涡抑制效果好,对高速泵空化改善最明显的方案。通过分析得出的结论如下:(1)利用正交试验方法得到了适应此高速离心泵的孔板抑制装置的几何尺寸,即孔板厚度B=20mm,孔板距离诱导轮进口的距离L=1.15R,孔板内径D0=1.5R,其中R为进口段半径。(2)在设计工况下得出了,-10°/20°和-20°/10°这两个方案无论在控制回流漩涡上还是对诱导轮和叶轮的内部流场和空化的影响上,相对其他方案都有较大的优势。在小流量工况下,其中-20°/10°方案对于进口段回流漩涡控制有良好的效果,诱导轮和叶轮的吸力面和压力面的压力变化很小,空化方面展现结果最好的为-20°/10°和20°/20°方案。(3)对高速泵的外特性进行分析,由扬程性能曲线可知,在小流量0.6Qd的工况下,对扬程提高较大的方案为20°/20°方案;在设计工况下,扬程提高最明显的为-20°/10°和-10°/20°方案。由效率曲线可知,在小流量0.6Qd的工况下,效率提高最大的方案为0°/0°方案;在设计工况下,整体效率达到了一个最大值,对效率提高最大的为-20°/10°和-10°/20°方案,这两个方案的效率大于传统型孔板0°/0°方案大约2个百分点。综上所述,本文提出的一种抑制高速泵进口空化的孔板装置,能够有效地抑制泵进口的回流漩涡和内部的空化,同时有效的提高高速泵的水力性能。
[Abstract]:High speed centrifugal pump is a special centrifugal pump with small flow rate and high head. Due to the reason of high rotational speed, it is very easy to produce backflow vortex and cavitation erosion in the inlet and inside of the pump, and there are many ways to reduce the backflow vortex and cavitation erosion at present. The method of adding orifice plate and induction wheel in front of impeller can effectively restrain backflow vortex and cavitation of impeller and thus improve hydraulic performance of high speed pump. Up to now, no scholar has studied the influence of orifice plate on reflux vortex by changing the form of orifice plate. In this paper, the influence of different orifice plate suppression device on inlet reflux vortex and cavitation erosion of high speed pump is analyzed. The optimum cavitation inhibition device at the inlet of high speed pump was determined. Firstly, the geometric size of the orifice plate is determined by single-phase steady flow analysis, the optimum thickness of the plate, the distance and aperture to the inlet of the inducer are determined by the orthogonal experimental method, and nine schemes are designed. Secondly, 25 schemes are designed by changing the angle of the front and rear tilting of the orifice plate, and the five schemes with the best hydraulic performance for the high speed pump are obtained by calculation and analysis. Finally, through the calculation and analysis of the five schemes under the cavitation condition, the best scheme is selected to restrain the backflow vortex and improve the cavitation of the high speed pump. The conclusions are as follows: (1) the geometric size of the orifice suppression device suitable for this high speed centrifugal pump is obtained by using the orthogonal test method. That is, the thickness of orifice plate is 20 mm, the distance between orifice plate and induction wheel is 1.15R, and the inner diameter of hole plate is D0 1. 5R, where R is the radius of inlet section.) under the design condition, two schemes, namely, 10 掳-10 掳/ 20 掳/ 20 掳and -20 掳/ 10 掳, are obtained, both on the control of backflow vortex and on the induction wheel and impeller. In terms of the internal flow field and the effect of cavitation, Compared with other programs, there is a great advantage. Under the condition of small flow rate, -20 掳/ 10 掳scheme has a good effect on the return vortex control of inlet section, and the pressure of suction surface and pressure surface of induction wheel and impeller have little change. The best results of cavitation are -20 掳/ 10 掳and 20 掳/ 20 掳scheme. We analyze the external characteristics of the high speed pump. According to the performance curve of the head, we can see that under the condition of small flow rate 0.6Qd, the scheme of increasing the lift is 20 掳/ 20 掳, and in the design condition, The most significant elevation was -20 掳/ 10 掳and -10 掳/ -10 掳/ 20 掳. According to the efficiency curve, under the condition of small flow rate 0.6Qd, the maximum efficiency improvement scheme is 0 掳/ 0 掳scheme, and in the design condition, the overall efficiency reaches a maximum, and the maximum efficiency increases are -20 掳/ 10 掳and -10 掳/ 20 掳scheme. The efficiency of the two schemes is about 2 percentage points higher than that of the traditional orifice plate 0 掳/ 0 掳scheme. To sum up, a kind of orifice plate device which can restrain the cavitation at the inlet of the high speed pump is put forward in this paper, which can effectively restrain the return vortex and the cavitation inside the inlet of the pump, and at the same time, improve the hydraulic performance of the high speed pump effectively.
【学位授予单位】：西华大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH311

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