平面S形轴伸泵装置水力特性

发布时间：2018-03-04 18:49

本文选题：平面S形轴伸泵　切入点：数值模拟　出处：《扬州大学》2017年硕士论文　论文类型：学位论文

【摘要】：S形轴伸泵系统是一种流道呈S形的轴伸泵系统。S形轴伸泵系统在我国的建设应用较早,但由于性能欠佳、效率不高,难以满足节能等实际工程技术需要,所以应用发展缓慢。但该泵系统结构简单,维修方便,不受泵大小制约,可用于各种尺寸的轴流泵系统,如果能保证节能高效,应用前景十分广阔。近年来,一些学者研发了新型S形轴伸泵系统,使得这种泵系统突破了效率不高的瓶颈,并将其应用于工程领域。目前国内外学者对S形轴伸泵系统的水力特性已经有了一些研究,但还停留在对前置式或后置式单个形式的泵装置研究上,并没有文献对前置式和后置式这两种不同形式的泵装置的水力特性进行综合比较分析。副导叶是一种位于导叶后侧、处于出水流道内部的整流装置,它可以将出水流道中水流剩余环量进一步回收,从而改善出水流道的内部流态,减小水力损失。但在流道中加入副导叶势必会增大摩擦损失。目前,对于在装置内部加入副导叶能否提高装置性能还缺乏深入研究。本文采用CFX软件,分别对平面S形前置与后置轴伸泵装置进行数值模拟计算。根据模拟结果分析两种泵形式的内外特性,并进行对比分析。在两种泵形式的出水流道不同位置加入不同形状的副导叶,观察各个方案能否通过减小水流剩余环量来最终提高装置性能,并通过对比各个方案的装置性能,探索副导叶合适的安装位置与形状。数值计算结果表明:前置轴伸泵装置在Q=3001/s时效率最高,为76.67%,对应的扬程为3.088m,后置轴伸泵装置在Q=2801/s时效率最高,为76.85%,对应的扬程为3.448m。后置式在小流量工况时效率高于前置式,适用于偏小流量工况运行,前置式则是在大流量工况时效率更高,适用于偏大流量工况运行。小流量工况时后置式扬程高于前置式,功率则略低于前置式,大流量工况时前置式扬程较高,功率明显高于后置式。从两种泵形式进出水流道水力特性的对比中可以发现,后置式进水流道出口的流速均匀度在全工况下高于前置式,而进水流道水力损失则在全工况下小于前置式,进水流道水力特性更佳。两种泵形式出水流道水力损失在小流量工况时相近,设计及大流量工况时前置式更小。前置式导叶出口外周的环量在小流量工况时大于后置式,在Q达到300L/s后,两个泵装置的环量均趋近于0,截面上的正负环量相互抵消。从前置式出水流道中截取与后置式弯管相同长度的出水等效管,弯管与出水等效管水力损失皆在设计工况时取得最小值,弯管水力损失占出水流道水力损失的比重更大,弯管出口的环量在小流量工况时更小,大流量工况时更大。在平面S形前置轴伸泵装置出水流道不同位置处加入矩形以及流线形副导叶,比较流道的水力特性及装置的能量性能。结果表明:各方案中的副导叶均能有效地回收水流的剩余环量。相同位置的流线形副导叶方案的装置性能优于矩形副导叶方案。两种形状的副导叶方案总的趋势是离流道进口越远,装置性能越好。离流道进口一定距离处加入副导叶可以提高装置的性能。在平面S形后置轴伸泵装置的弯管出口以及出水流道出口加入流线形副导叶后,均能有效地回收水流的剩余环量,但装置效率均略微下降,同时,副导叶置于弯管出口的方案效率略低于副导叶置于流道出口的方案。根据对副导叶在两种泵形式中的尝试可以说明,在流道中设置副导叶虽能有效减小水流剩余环量,但并不一定可以提高装置效率。所以在其他形式的泵装置中使用副导叶能否有效需要进行验证。
[Abstract]:S shaped shaft pump system is a kind of channel is in the shape of S shaft extension pump system.S - shaft pump system in the construction of China earlier, but due to poor performance, the efficiency is not high, it is difficult to meet the actual needs of energy saving engineering technology, so the application of slow development. But the pump system has the advantages of simple structure, convenient maintenance no, the pump size constraints, can be used for various sizes of axial flow pump system, if can guarantee the energy efficiency, and has very broad application prospects. In recent years, some scholars have developed a new type of S shaped shaft pump system, the pump system to break the bottleneck of efficiency is not high, and its application in engineering field at present. The hydraulic characteristics of the domestic and foreign scholars on the S shaped shaft extension pump system has some research, but still stay in the study on the pre - or post pump type single form, and no literature on the front and rear hydraulic type these two different forms of pumping unit The characteristics were analyzed. The vice guide vane is a guide vane located in the rear side rectifier outlet inside in, it can be in the water outlet residual circulation further recovery, so as to improve the flow of internal flow, reduce the hydraulic losses. But in the channel with side guide vane is bound to increase the friction loss at present, the lack of in-depth study in the interior of the device side guide vane can improve adding device performance. This paper uses CFX software, respectively on the plane S shaped front and rear shaft pump were numerically simulated. According to the analysis of simulation results and characteristics of two kinds of pump, and comparative analysis. In the two pair of guide vane a pump outlet form different positions with different shapes, each observation scheme can reduce the flow through the residual circulation to ultimately improve device performance, and the performance of each program comparison device, To explore the installation position of vice guide vane and appropriate shape. The numerical results show that the front shaft pump device when Q=3001/s is 76.67%, the highest efficiency, the corresponding head 3.088m, rear shaft pump device when Q=2801/s is 76.85%, the highest efficiency, the corresponding head 3.448m. rear efficiency is higher than that in the small flow condition front type, suitable for small flow operation, front is efficiency in the large flow condition is higher, suitable for large flow operation. Small flow condition when the rear head is higher than the front, power is slightly lower than the front, at large flow condition of front power was significantly higher than that of the high lift, rear comparing import hydraulic characteristics from two kinds of pump form can be found in the rear inlet exit velocity uniformity in all conditions is higher than the front, and the water hydraulic loss is less than in full working condition Front type, hydraulic characteristics of inlet passage is better. Two kinds of pump hydraulic loss of discharge passage in the vicinity of the small flow condition, and design at large flow condition in front of smaller. The circulation of front guide vane outlet peripheral is greater than the rear in the small flow condition, the Q reached 300L/s, two circulation pump the devices are close to 0, positive and negative circulation offset section. The water equivalent of the passage in the interception from the front and rear pipe of the same length tube, pipe and water pipe hydraulic losses are equivalent in the design condition has a minimum value, the proportion of water pipe hydraulic loss of hydraulic loss is larger, ring the amount of export pipe in the small flow condition is smaller, more at large flow condition. With rectangular and streamlined side guide vanes in the plane S shaped front shaft extension at different positions of the pump outlet device, hydraulic characteristics and flow of the device can The amount of the performance. The results show that the residual circulation guide in the schemes can effectively recover the leaves with water. The same position of the streamline shaped side guide device is better than rectangular side stators scheme. Two kinds of leaf shape guide leaf total program is the trend of the farther away from the inlet, the better the performance of device from the inlet at a certain distance to the secondary vane can improve the performance of the device. In plane S pump shaft bending shape rear outlet and outlet outlet join streamline vice guide vane, residual circulation can effectively recycle water, but the device efficiency was slightly lower, at the same time, the efficiency of the proposed schemes the vice guide vane should be slightly lower than the side bend outlet guide vane outlet in the scheme. According to that attempt to side guide vanes in the two pumps in the form of side guide vane can effectively reduce the flow quantity of the remaining ring set in the port, but not necessarily can Improve the efficiency of the device. Therefore, it is necessary to verify the use of the secondary guide leaves in other types of pump devices.

【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV136.2

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