可调前置导叶对轴流泵性能的影响

发布时间：2018-05-13 21:21

本文选题：轴流泵 + 前置导叶　；参考：《扬州大学》2012年硕士论文

【摘要】：大型轴流泵通常采用变角方式调节运行工况。叶轮叶片动调节机构在立式泵中的应用已比较成熟,但此调节机构在低扬程泵站经常采用的卧式泵装置中直接运用会存在问题。由于低扬程卧式泵转速较低,需要齿轮箱进行减速,而齿轮箱位于水泵和电机之间,这就造成了叶轮叶片动调节机构布置上的困难。因此通常的做法是将叶片调节机构布置在叶轮前面的直导叶体中,这种情况下,通过调节前置导叶来实现工况调节的方法就值得考虑。相比于叶轮叶片动调节机构,调节前置导叶的调节机构布置在静止的部件上,结构可简化,成本可降低。为了验证通过前置导叶调节水泵工况的可行性和优劣,对比加装前导叶前后轴流泵性能变化的研究就很有意义。本文在分析前置导叶工况调节机理的基础上,采用三维雷诺平均N-S方程和标准k-ε紊流模型进行三维流场的数值计算,分析前置导叶调节工况的可行性及具体的调节效果。主要内容包括：(1)叶轮叶片安放角对轴流泵特性的影响；(2)叶轮叶片安放角固定时,前置导叶叶片安放角对轴流泵能量特性和汽蚀特性的影响；(3)前置导叶的能量损失分析；(4)两种不同前置导叶叶片数对性能调节效果的影响分析。研究表明,通过改变前置导叶安放角可有效改变轴流泵的特性曲线,实现工况调节的目的。通用性能曲线上的高效区分布与叶轮叶片调节的高效区分布有明显差异。叶轮叶片安放角调节,高效区鸭蛋圆长轴基本上与流量轴平行,适用于扬程变幅小,流量调节范围大的应用场合；前置导叶安放角调节,高效区鸭蛋圆长轴方向接近沿Q-H线方向分布,比较适用于扬程变幅较大的应用场合。导叶安放角增大后,导叶水力损失明显增大。导叶安放角适合往正角度方向调节。前置导叶还能改善轴流泵的马鞍区,使高扬程工况运行时更加平稳。前置导叶使泵的必需汽蚀余量有所增加,在设计工况约增加0.5米。前置导叶有水力损失会造成泵整体效率的有所下降。但与采用叶轮进口前布置叶轮叶片调节机构的方式相比,效率下降并不明显,因此,采用可调节前置导叶实现泵工况调节的方式在工程上具有应用价值。
[Abstract]:Large axial flow pump is usually used to adjust the operation conditions. The application of impeller vane dynamic regulating mechanism in vertical pump is mature, but there are some problems in the application of this regulating mechanism in the horizontal pump device which is often used in low head pump station. Because of the low speed of the horizontal pump with low head, the gear box is needed to slow down, and the gear box lies between the pump and the motor, which makes it difficult to arrange the dynamic regulating mechanism of the impeller blade. Therefore, the usual method is to arrange the blade regulating mechanism in the body of the straight guide blade in front of the impeller. In this case, the method of adjusting the working condition by adjusting the front guide vane is worth considering. Compared with the dynamic regulating mechanism of the impeller blade, the adjusting mechanism of the front guide vane is arranged on the static parts, the structure can be simplified and the cost can be reduced. In order to verify the feasibility and merits of regulating the pump condition by the front guide vane, it is of great significance to compare the performance changes of the axial flow pump before and after the installation of the front guide vane. In this paper, based on the analysis of the regulating mechanism of the leading guide vane, the 3-D Reynolds average N-S equation and the standard k- 蔚 turbulent model are used to calculate the three-dimensional flow field, and the feasibility and the concrete regulation effect of the pre-guide vane regulating condition are analyzed. The main contents include: (1) the influence of impeller blade placement angle on the characteristics of axial flow pump; (2) when impeller blade placement angle is fixed, The influence of vane placement angle on the energy and cavitation characteristics of axial flow pump; Analysis of the energy loss of the front guide vane; Analysis of the effect of the number of the two kinds of front guide vane on the performance adjustment effect. The research shows that the characteristic curve of axial flow pump can be changed effectively by changing the angle of front guide vane, and the purpose of operating condition adjustment can be realized. The distribution of high efficiency zone on general performance curve is obviously different from that of impeller blade regulation. Impeller blade placement angle adjustment, the high efficiency area duck egg circle long axis is basically parallel to the flow axis, is suitable for the lift variable amplitude small, the flow rate adjustment scope is big, the front guide vane placement angle adjustment, The direction of round long axis of duck egg in high efficiency area is close to the direction of Q-H line, which is more suitable for the application of large amplitude variation of head. When the angle of guide vane is increased, the hydraulic loss of guide vane increases obviously. Guide vane angle is suitable for direct angle adjustment. The front guide vane can also improve the saddle area of the axial flow pump and make the operation of high head more stable. The required cavitation allowance of the pump is increased by 0.5 m in the design condition. The hydraulic loss of the front guide vane will lead to a decrease in the overall efficiency of the pump. However, compared with the way in which the impeller blade regulating mechanism is arranged before the inlet of the impeller, the efficiency is not obviously decreased. Therefore, it is valuable to use the adjustable front guide vane to realize the pump condition regulation in engineering.
【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH312

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