蜗壳进口宽度对离心泵性能影响的数值研究
发布时间：2019-02-28 09:34
【摘要】：离心泵主要由叶轮和蜗壳两大过流部件组成，共同决定着离心泵的性能。蜗壳作为离心泵的一个重要过流部件，起着重要的导流与扩压作用，其设计的好坏对泵的性能有着重大影响。而长期以来，人们往往将研究重点集中在叶轮上，很大程度上忽视了对蜗壳及其与叶轮匹配关系的研究。这就造成叶轮的水力性能往往非常优异，一旦和蜗壳配合起来工作，各项性能指标都会大幅度下降，并且伴随有振动、噪声等非稳定工况。因此，要大幅度提高离心泵的各项性能指标，必须解决叶轮与蜗壳相互匹配的问题。 本文通过改变蜗壳的进口宽度，对蜗壳与叶轮的匹配关系进行了数值研究。首先，本文对离心泵蜗壳的水力设计作了详细的阐述，着重介绍了蜗壳梯形截面的计算方法，并用此方法，在保证蜗壳断面面积不变的前提下，重新设计了两个进口宽度与原型泵互不相同的蜗壳，分别与原型泵叶轮组合作为本文研究所用的模型。利用FLUENT软件对离心泵内部流动进行了三维定常和非定常数值模拟，计算结果较全面地揭示了三个模型各工况下全流道内的静压和速度分布规律，分析了蜗壳进口宽度对离心泵性能及蜗壳内部压力脉动特性的影响，并得到以下主要结论： （1）蜗壳进口宽度对离心泵外特性的影响。三个模型的外特性预测结果表明，泵的效率和扬程均随蜗壳进口宽度的增加而稍稍降低。 （2）蜗壳进口宽度对静压场和速度场分布的影响。蜗壳进口宽度的改变对流场分布也有一定的影响。同一流量下，靠近蜗壳壁面的流场高压区域随着蜗壳进口宽度的增加而有所减小，从第八断面到出口的蜗壳扩散段，这种变化非常显著；随着蜗壳进口宽度的增加，隔舌处和叶片出口的速度有所减小，蜗壳扩散段的流场受蜗壳进口宽度的影响也比较明显，随着蜗壳进口宽度的增大，蜗壳扩散段内的低速区域扩大。 （3）蜗壳进口宽度对蜗壳断面内绝对速度分布的影响。蜗壳进口宽度越大，进口处的速度值越小，速度分布越向壁面分散，旋涡的范围也越大。 （4）蜗壳进口宽度对蜗壳进口处静压和绝对速度分布的影响。各个流量下，总体上蜗壳进口处的压力随进口宽度增大而略有增加，而压力波动幅度却随蜗壳进口宽度增大而有所减小。各流量工况下，蜗壳进口宽度对隔舌处的径向速度影响相对明显，此处的径向速度随着蜗壳进口宽度增大而有所减小。 （5）蜗壳进口宽度对蜗壳内部压力脉动特性的影响。蜗壳隔舌附近的压力脉动幅度和强度较大，蜗壳流道内距离隔舌越近的监测点，，其压力脉动幅度和强度越大。蜗壳进口宽度的改变对蜗壳壁面和进口处压力脉动特性有一定的影响，总体上蜗壳进口越宽，压力脉动的幅度越小。
[Abstract]:Centrifugal pump mainly consists of impeller and volute, which determines the performance of centrifugal pump. Volute, as an important over-flow part of centrifugal pump, plays an important role in diversion and pressure expansion. The design of volute has a great influence on the performance of pump. For a long time, people tend to focus on the impeller and ignore the study of volute and its matching relation with impeller to a great extent. As a result, the hydraulic performance of the impeller is often very excellent. Once the impeller works together with the volute, all the performance indexes will be greatly reduced, accompanied by unstable conditions such as vibration, noise and so on. Therefore, in order to greatly improve the performance of centrifugal pump, it is necessary to solve the problem of matching impeller and volute. In this paper, the matching relationship between volute and impeller is studied by changing the inlet width of volute. Firstly, the hydraulic design of the spiral case of centrifugal pump is described in detail, and the calculation method of trapezoidal cross section of the spiral case is emphatically introduced. With this method, the cross-section area of the spiral case is not changed under the premise of keeping the cross-section area of the volute case unchanged. Two volute cases with different inlet width from that of prototype pump are redesigned, respectively, which are combined with the impeller of prototype pump as the model used in this paper. The three-dimensional steady and unsteady numerical simulation of the internal flow of centrifugal pump is carried out by using FLUENT software. The calculated results reveal the static pressure and velocity distribution in the full channel of the three models in all working conditions. The influence of volute inlet width on the performance of centrifugal pump and the pressure pulsation characteristics inside volute case are analyzed. The main conclusions are as follows: (1) the influence of volute inlet width on external characteristics of centrifugal pump. The prediction results of the external characteristics of the three models show that the efficiency and head of the pump decrease slightly with the increase of the inlet width of the volute. (2) the influence of volute inlet width on the distribution of static pressure field and velocity field. The change of the inlet width of the volute also has a certain effect on the distribution of the flow field. At the same flow rate, the high pressure flow field near the wall of the volute case decreases with the increase of the inlet width of the volute, and this change is very significant in the diffusion section from the eighth section to the outlet. With the increase of the inlet width of the volute, the velocity of the diaphragm and the outlet of the blade decreases, and the flow field in the diffusion section of the volute is also influenced by the width of the inlet of the volute, and with the increase of the width of the inlet of the volute, The low-speed region in the diffusion section of the volute is enlarged. (3) the influence of inlet width of volute on the distribution of absolute velocity in the section of volute. The larger the inlet width of the volute is, the smaller the velocity value at the inlet is, the more dispersed the velocity distribution is towards the wall, and the larger the scope of the vortex is. (4) the influence of the inlet width of the volute on the static pressure and absolute velocity distribution at the inlet of the volute. At each flow rate, the pressure at the inlet of the volute increases slightly with the increase of the inlet width, while the amplitude of the pressure fluctuation decreases with the increase of the inlet width of the volute. Under various flow conditions, the inlet width of the volute has a relatively obvious effect on the radial velocity at the tongue partition, and the radial velocity here decreases with the increase of the inlet width of the volute. (5) the influence of the inlet width of the volute on the pressure fluctuation characteristics of the volute. The pressure fluctuation amplitude and intensity near the volute septum is larger, and the closer the volute passage is to the diaphragm, the greater the pressure fluctuation amplitude and strength are. The variation of the inlet width of the volute has a certain effect on the pressure fluctuation characteristics at the wall and inlet of the volute. Generally, the wider the inlet of the volute case is, the smaller the amplitude of the pressure fluctuation is.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH311
本文编号：2431700
[Abstract]:Centrifugal pump mainly consists of impeller and volute, which determines the performance of centrifugal pump. Volute, as an important over-flow part of centrifugal pump, plays an important role in diversion and pressure expansion. The design of volute has a great influence on the performance of pump. For a long time, people tend to focus on the impeller and ignore the study of volute and its matching relation with impeller to a great extent. As a result, the hydraulic performance of the impeller is often very excellent. Once the impeller works together with the volute, all the performance indexes will be greatly reduced, accompanied by unstable conditions such as vibration, noise and so on. Therefore, in order to greatly improve the performance of centrifugal pump, it is necessary to solve the problem of matching impeller and volute. In this paper, the matching relationship between volute and impeller is studied by changing the inlet width of volute. Firstly, the hydraulic design of the spiral case of centrifugal pump is described in detail, and the calculation method of trapezoidal cross section of the spiral case is emphatically introduced. With this method, the cross-section area of the spiral case is not changed under the premise of keeping the cross-section area of the volute case unchanged. Two volute cases with different inlet width from that of prototype pump are redesigned, respectively, which are combined with the impeller of prototype pump as the model used in this paper. The three-dimensional steady and unsteady numerical simulation of the internal flow of centrifugal pump is carried out by using FLUENT software. The calculated results reveal the static pressure and velocity distribution in the full channel of the three models in all working conditions. The influence of volute inlet width on the performance of centrifugal pump and the pressure pulsation characteristics inside volute case are analyzed. The main conclusions are as follows: (1) the influence of volute inlet width on external characteristics of centrifugal pump. The prediction results of the external characteristics of the three models show that the efficiency and head of the pump decrease slightly with the increase of the inlet width of the volute. (2) the influence of volute inlet width on the distribution of static pressure field and velocity field. The change of the inlet width of the volute also has a certain effect on the distribution of the flow field. At the same flow rate, the high pressure flow field near the wall of the volute case decreases with the increase of the inlet width of the volute, and this change is very significant in the diffusion section from the eighth section to the outlet. With the increase of the inlet width of the volute, the velocity of the diaphragm and the outlet of the blade decreases, and the flow field in the diffusion section of the volute is also influenced by the width of the inlet of the volute, and with the increase of the width of the inlet of the volute, The low-speed region in the diffusion section of the volute is enlarged. (3) the influence of inlet width of volute on the distribution of absolute velocity in the section of volute. The larger the inlet width of the volute is, the smaller the velocity value at the inlet is, the more dispersed the velocity distribution is towards the wall, and the larger the scope of the vortex is. (4) the influence of the inlet width of the volute on the static pressure and absolute velocity distribution at the inlet of the volute. At each flow rate, the pressure at the inlet of the volute increases slightly with the increase of the inlet width, while the amplitude of the pressure fluctuation decreases with the increase of the inlet width of the volute. Under various flow conditions, the inlet width of the volute has a relatively obvious effect on the radial velocity at the tongue partition, and the radial velocity here decreases with the increase of the inlet width of the volute. (5) the influence of the inlet width of the volute on the pressure fluctuation characteristics of the volute. The pressure fluctuation amplitude and intensity near the volute septum is larger, and the closer the volute passage is to the diaphragm, the greater the pressure fluctuation amplitude and strength are. The variation of the inlet width of the volute has a certain effect on the pressure fluctuation characteristics at the wall and inlet of the volute. Generally, the wider the inlet of the volute case is, the smaller the amplitude of the pressure fluctuation is.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH311
【引证文献】
相关博士学位论文 前1条
1 吴登昊;高效低振动循环泵设计与试验研究[D];江苏大学;2013年
本文编号：2431700
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