离心泵叶片开槽抑制空化数值模拟
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摘要
为了进一步提高低比转数离心泵的空化性能,提出在叶片压力面开槽的方法来抑制空化。针对离心泵运行过程中产生空化的流动特点,基于Kubota空化模型,采用SST k-ω模型对在相同工况下的离心泵中两相流动进行数值模拟与分析。模拟结果表明:叶片表面开槽后,离心泵各个工况下的扬程有所上升,在设计点扬程提高12. 8%,同时效率提高4. 2%。叶片开槽可以有效阻止低压区域向外扩张,改变压力的分布,对离心泵内各个阶段空化均有抑制作用。叶片开槽可以优化流场结构,使流道内的压力增加,减小空泡的体积分数。叶片开槽时离心泵叶轮内空泡体积在空化的各个阶段均小于无槽时叶轮内空泡体积,在空化发展阶段,开槽时空泡体积持续衰减。
Centrifugal pumps are widely used to deliver liquid media in agriculture,pharmacy,industry,etc. Compared with the case delivering pure liquid such as water,centrifugal pumps not only have lower efficiency but also are subject to severe vibration,noise and erosion when delivering cavity two-phase flow. In order to further improve the cavitation performance of low specific rotation centrifugal pump,a method of making the blade slotted to control cavitation in a centrifugal pump was proposed. The slotted impeller blade near the inlet of centrifugal pump was studied. According to the flow characteristics of cavitation in centrifugal pump and the cavitation dynamics model of Kubota cavitation model,the SST k-ωmodel was used to simulate and analyze the two-phase flow in a centrifugal pump under the same working conditions. The simulation results showed that after the blade surface was slotted,the head of the centrifugal pump was increased,and the head of the centrifugal pump was increased by 12. 8% at the design point,and the efficiency was increased by 4. 2%. The slotted blade can effectively prevent the low pressure region from expanding outward,change the pressure distribution and inhibit the cavitation in every stage of the centrifugal pump. The slotted blade can optimize the flow field structure,increase the pressure in the flow channel and reduce the volume fraction of the cavitation. The cavitation volume of centrifugal pump impeller in every stage of cavitation was smaller than that of impeller without slot when the blade was slotted. In the stage of cavitation development,the volume of slotted space-time bubble continued to decay.
Centrifugal pumps are widely used to deliver liquid media in agriculture,pharmacy,industry,etc. Compared with the case delivering pure liquid such as water,centrifugal pumps not only have lower efficiency but also are subject to severe vibration,noise and erosion when delivering cavity two-phase flow. In order to further improve the cavitation performance of low specific rotation centrifugal pump,a method of making the blade slotted to control cavitation in a centrifugal pump was proposed. The slotted impeller blade near the inlet of centrifugal pump was studied. According to the flow characteristics of cavitation in centrifugal pump and the cavitation dynamics model of Kubota cavitation model,the SST k-ωmodel was used to simulate and analyze the two-phase flow in a centrifugal pump under the same working conditions. The simulation results showed that after the blade surface was slotted,the head of the centrifugal pump was increased,and the head of the centrifugal pump was increased by 12. 8% at the design point,and the efficiency was increased by 4. 2%. The slotted blade can effectively prevent the low pressure region from expanding outward,change the pressure distribution and inhibit the cavitation in every stage of the centrifugal pump. The slotted blade can optimize the flow field structure,increase the pressure in the flow channel and reduce the volume fraction of the cavitation. The cavitation volume of centrifugal pump impeller in every stage of cavitation was smaller than that of impeller without slot when the blade was slotted. In the stage of cavitation development,the volume of slotted space-time bubble continued to decay.
引文
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15 JI Bin,LUO Xianwu,WANG Xin,et al.Unsteady numerical simulation of cavitating turbulent flow around a hughly skewed model marine propeller[J].ASME Journal of Fluids Engineering,2011,133(1):011102.1-011102.8.
16李晓俊,袁寿其,潘中永,等.离心泵边界层网格的实现及应用评价[J].农业工程学报,2012,28(20):67-72.LI Xiaojun,YUAN Shouqi,PAN Zhongyong,et al.Realization and application of near-wall mesh in centrifugal pumps[J].Transactions of the CSAE,2012,28(20):67-72.(in Chinese)
17王福军.计算流体动力学分析[M].北京:清华大学出版社,2004.
18 ZWART P J,GERBER A G,BELAMRI T.A two-phase flow model for predicting cavitation dynamics[C]∥Proceedings of International Conference on Multiphase Flow.Yokohama,2004.
19 JI Bin,LUO Xianwu,WU Yulin,et al.Numerical analysis of unsteady cavitating turbulent flow and shedding horse-shoe vortex structure around a twisted hydrofoil[J].International Journal of Multiphase Flow,2013,51:33-43.
20 ANSYS-CFX.Discretization of the governing equations[Z].ANSYS CFX Help Document,2012.
21王维军.低比转速离心泵空化流动控制的研究[D].镇江:江苏大学,2016.
2 SIVAGNANASUNDARAM S,SPENCE S,EARLYEARLY J,et al.Aninvestigation of compressor map width enhancement and the inducer flow field using various configurations of shroud bleed slot[C]∥ASME Turbo Expo 2010:Power for Land,Sea,and Air,2010:23-30.
3周敏,王如根,曹朝辉,等.开槽处理技术对叶片尾缘气流流动特性的影响[J].航空动力学报,2007,22(7):1100-1105.ZHOU Min,WANG Rugen,CAO Zhaohui,et al.The effect of slotting technology on the flow characteristics of the tail edge of the blade[J].Aero Power Journal,2007,22(7):1100-1105.(in Chinese)
4罗先武,张瑶,彭俊奇,等.叶轮进口几何参数对离心泵空化性能的影响[J].清华大学学报(自然科学版),2008,48(5):836-839.LUO Xianwu,ZHANG Yao,PENG Junqi,et al.Effect of impeller inlet geometry on centrifugal pump cavitation performance[J].Journal of Tsinghua University(Science and Technology),2008,48(5):836-839.(in Chinese)
5 KUIPER G.New developments and propeller design[J].Journal of Hydrodynamics,2010,22(5):7-16.
6王洋,谢山峰,王维军,等.开缝叶片低比转数离心泵空化性能的数值模拟[J].排灌机械工程学报,2016,34(3):210-215.WANG Yang,XIE Shanfeng,WANG Weijun,et al.Numerical simulation of cavitation performance of low specific speed centrifugal pump with slotted blades[J].Journal of Drainage and Irrigation Machinery Engineering,2016,34(3):210-215.(in Chinese)
7赵伟国,赵国寿,咸丽霞,等.离心泵叶片表面布置障碍物抑制空化的数值模拟与实验[J/OL].农业机械学报,2017,48(9):111-120.http:∥www.j-csam.org/jcsam/ch/reader/view_abstract.aspx?file_no=20170914&flag=1.DOI:10.6041/j.issn.1000-1298.2017.09.014.ZHAO Weiguo,ZHAO Guoshou,XIAN Lixia,et al.Numerical simulation and experiment of obstacle arrangement on centrifugal pump blade to suppress cavitation[J/OL].Transactions of the Chinese Society for Agricultural Machinery,2017,48(9):111-120.(in Chinese)
8黄思,李作俊.具有长短叶片离心泵的全三维湍流数值模拟[J].化工机械,2006,33(2):90-98.HUANG Si,LI Zuojun.Three dimensional turbulence has long short blade centrifugal pump numerical simulation[J].Chemical Engineering&Machinery,2006,33(2):90-98.(in Chinese)
9韩伟,高丽敏,白莹,等.高速离心叶轮叶片开缝的数值研究[J].流体机械,2011,39(11):17-21.HAN Wei,GAO Limin,BAI Ying,et al.Numerical study on the opening of high speed centrifugal impeller blade[J].Fluid Machinery,2011,39(11):17-21.(in Chinese)
10赵伟国.水翼云空化及其控制机理研究[D].杭州:浙江大学,2012.
11关醒凡.泵的理论与设计[M].北京:机械工业出版社,1987:632-636.
12王靖超.端部开槽叶栅流场及强度分析[D].哈尔滨:哈尔滨工业大学,2008.
13陈国强,王乘,姬晋延.轴流式水轮机叶片刚度和强度有限元分析[J].机械强度,2003,25(6):690-693.CHEN Guoqiang,WANG Cheng,JI Jinyan.Finite element analysis of stiffness and strength of axial flow turbine blade[J].The Mechanical Strength,2003,25(6):690-693.(in Chinese)
14张德胜,吴苏青,施卫东.不同湍流模型在轴流泵叶顶泄漏涡模拟中的应用与验证[J].农业工程学报,2013,29(13):46-53.ZHANG Desheng,WU Suqing,SHI Weidong,et al.Application and experiment of different turbulence models for simulating of the tip leakage vortex in axial flow pump[J].Transactions of the CSAE,2013,29(13):46-53.(in Chinese)
15 JI Bin,LUO Xianwu,WANG Xin,et al.Unsteady numerical simulation of cavitating turbulent flow around a hughly skewed model marine propeller[J].ASME Journal of Fluids Engineering,2011,133(1):011102.1-011102.8.
16李晓俊,袁寿其,潘中永,等.离心泵边界层网格的实现及应用评价[J].农业工程学报,2012,28(20):67-72.LI Xiaojun,YUAN Shouqi,PAN Zhongyong,et al.Realization and application of near-wall mesh in centrifugal pumps[J].Transactions of the CSAE,2012,28(20):67-72.(in Chinese)
17王福军.计算流体动力学分析[M].北京:清华大学出版社,2004.
18 ZWART P J,GERBER A G,BELAMRI T.A two-phase flow model for predicting cavitation dynamics[C]∥Proceedings of International Conference on Multiphase Flow.Yokohama,2004.
19 JI Bin,LUO Xianwu,WU Yulin,et al.Numerical analysis of unsteady cavitating turbulent flow and shedding horse-shoe vortex structure around a twisted hydrofoil[J].International Journal of Multiphase Flow,2013,51:33-43.
20 ANSYS-CFX.Discretization of the governing equations[Z].ANSYS CFX Help Document,2012.
21王维军.低比转速离心泵空化流动控制的研究[D].镇江:江苏大学,2016.