多级离心泵内时序效应数值研究

发布时间：2018-04-29 15:00

本文选题：多级离心泵 + 时序效应　；参考：《西安理工大学》2017年硕士论文

【摘要】：对多级离心泵而言,时序效应对泵水力性能和压力脉动影响较大。本文应用商用CFD软件,以某中比转速两级离心泵为研究对象,采用三维粘性非定常数值模拟结合标准k-ε湍流模型,对设计工况下多级离心泵内的时序效应进行了探讨。主要工作包括以下两部分内容:一方面是动叶时序效应:保持首级叶轮位置不变,使得次级叶轮相对于首级叶轮周向每错开5°为一个时序位置,对四种时序位置下泵的内部流动进行了全流道数值模拟,并分析了外特性、内部流动、压力脉动、叶轮轴向力和径向力以及涡量变化。结果表明:叶轮时序位置的变化对泵的扬程影响达到2.9%,效率达到2.4%;首级转轮内部流场分布不受时序位置的影响,但在次级转轮内当叶轮交错15°时可以改善转轮出口流场和降低叶片荷载;时序位置对首级内的压力脉动没有产生明显的变化,然而在次级转轮和蜗壳内变化相对较明显,主要表现为压力脉动的相位发生偏移和叶轮内最大幅值降低20.21%,蜗壳内降低7.45%;叶轮周向位置调整会改变一倍叶频处径向力的脉动幅值和降低次级转轮涡量,但几乎不会影响轴向力的分布规律。另一方面是静叶时序效应:保持蜗壳位置不变,使得径向导叶相对于蜗壳隔舌周向旋转每错开13°为一个时序位置,对四种时序位置下泵内部流动进行了数值模拟,主要分析了时序位置对外特性、内部流动特性、压力脉动特性和叶轮径向力的影响。结果表明:随着时序位置的改变,多级离心泵的扬程出现先减小后增大再减小的趋势,效率变化刚好与扬程相反,最大扬程改变0.39m,最大效率增大约0.11%;时序位置影响首次级转轮内速度和压力分布,且对首级内的影响大于次级;时序位置对蜗壳内的压力脉动几乎没有影响,但对径向导叶进口内的压力脉动影响较大,主要为压力脉动相位发生偏移和主频处的最大幅值有所降低;合理的时序位置会改变一倍叶频处径向力的脉动幅值,最小幅值相对最大幅值减小约4.64%。
[Abstract]:For multistage centrifugal pump, timing effect has great influence on hydraulic performance and pressure pulsation. In this paper, commercial CFD software is used to study the time-series effect of a two-stage centrifugal pump under the design conditions by using three-dimensional viscous unsteady numerical simulation combined with the standard k- 蔚 turbulence model. The main work includes the following two parts: on the one hand, the timing effect of the moving impeller: keeping the position of the first impeller unchanged, so that the secondary impeller is in a sequential position with respect to each staggered 5 掳of the circumferential direction of the first stage impeller. The internal flow of the pump in four time series positions is numerically simulated, and the external characteristics, internal flow, pressure pulsation, axial and radial forces of impeller and vorticity are analyzed. The results show that the influence of the timing position of the impeller on the pump lift is 2.9, the efficiency is 2.4, and the flow field distribution in the first stage runner is not affected by the timing position. However, when the impeller is staggered at 15 掳, the flow field at the outlet of the runner can be improved and the blade load can be reduced. The pressure pulsation in the first stage has no obvious change in the timing position, but the change is relatively obvious in the secondary runner and the volute case. It mainly shows that the phase migration of pressure pulsation and the reduction of the maximum value in the impeller by 20.21 and 7.45 in the volute, the amplitude of pulsation of radial force at the frequency doubling of the impeller will be changed and the vorticity of the secondary runner will be reduced by adjusting the circumferential position of the impeller. But it has little effect on the distribution of axial force. On the other hand, the static blade timing effect: keeping the volute position unchanged, making the diameter guide blade one time sequence position for each staggered 13 掳of rotation in the circumferential direction of the diaphragm tongue of the volute. The flow inside the pump is numerically simulated under four timing positions. The effects of external position, internal flow, pressure pulsation and radial force of impeller are analyzed. The results show that with the change of timing position, the head of multistage centrifugal pump decreases first and then increases and then decreases, and the change of efficiency is just opposite to that of head. The maximum lift changes 0.39 m, the maximum efficiency increases about 0.11 m, the timing position affects the velocity and pressure distribution in the first stage runner, and the influence on the first stage is greater than that on the secondary stage, and the timing position has little effect on the pressure pulsation in the volute. But it has a great influence on the pressure pulsation in the inlet of the diameter guide blade, mainly for the phase migration of the pressure pulsation and the decrease of the maximum value at the main frequency, and the reasonable time sequence position will change the pulsation amplitude of the radial force at the double blade frequency. The minimum amplitude is decreased by about 4.64 relative to the maximum value.
【学位授予单位】：西安理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV136.2

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