液压节流阀内非定常空化特性的数值分析
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摘要
基于修正的RNG k-ε湍流模型并结合Schnerr-Sauer空化模型及多相流模型对液压节流阀内部非定常空化流动进行了数值计算,分析了节流阀内空化形态的周期性变化过程及其对应的内部流场的压力脉动特性,讨论了非定常空化形态演变与压力脉动之间的关系,同时研究了不同空化阶段对节流阀内速度场的影响差异。结果表明:节流阀内空化的发展是一种非定常的周期性过程,主要包括空化的产生、脱落以及溃灭;在空化初生时,不同位置截面在轴向速度分布上均未出现反向射流,但在空化溃灭阶段,不同位置截面在靠近壁面处均存在一个宽度大约1 mm的反向射流区,且不同截面位置所对应的反向射流的强度不同;阀口下游不同监测点处压力脉动的主频与空化结构演化的周期有着良好的一致性,此外还存在一个次级频率,对应为小尺度空化脱落、溃灭的频率。
Based on the modified RNG k-ε turbulence model combined with Schnerr-Sauer cavitation model and the multiphase flow model, unsteady cavitation flow in throttle valve was numerically calculated. The periodic variation process of unsteady cavitation form in throttle valve and the corresponding inner flow field's pressure fluctuation characteristics were analyzed. The relation between unsteady cavitation form evolution and pressure fluctuation was explored. Meanwhile, the differences among influences of different cavitation stages on velocity field in throttle valve were studied. The results showed that the development of cavitation in throttle valve is an unsteady periodic process mainly including cavitation generation, shedding and collapse; at the beginning of cavitation, backward jet does not appear for different positions' sections in axial velocity distribution; but in the stage of cavitation collapse, different positions' sections have a backward jet range with the width of about 1 mm near the wall, the backward jet intensities corresponding to different positions' sections are different; the main frequency of pressure fluctuation at different monitored points in the valve port downstream agrees well with the evolution frequency of cavitation structure; in addition, there is a secondary frequency corresponding to that of small scale cavitation shedding and collapse.
Based on the modified RNG k-ε turbulence model combined with Schnerr-Sauer cavitation model and the multiphase flow model, unsteady cavitation flow in throttle valve was numerically calculated. The periodic variation process of unsteady cavitation form in throttle valve and the corresponding inner flow field's pressure fluctuation characteristics were analyzed. The relation between unsteady cavitation form evolution and pressure fluctuation was explored. Meanwhile, the differences among influences of different cavitation stages on velocity field in throttle valve were studied. The results showed that the development of cavitation in throttle valve is an unsteady periodic process mainly including cavitation generation, shedding and collapse; at the beginning of cavitation, backward jet does not appear for different positions' sections in axial velocity distribution; but in the stage of cavitation collapse, different positions' sections have a backward jet range with the width of about 1 mm near the wall, the backward jet intensities corresponding to different positions' sections are different; the main frequency of pressure fluctuation at different monitored points in the valve port downstream agrees well with the evolution frequency of cavitation structure; in addition, there is a secondary frequency corresponding to that of small scale cavitation shedding and collapse.
引文
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[22] 安晓东,刘兴华,孙柏刚,等.电控单体泵锥阀下游区域瞬态流场变化特性研究[J].农业机械学报,2016,47(5):360-365.AN Xiaodong,LIU Xinghua,SUN Baigang,et al.Change characteristics of transient flow field in poppet valve downstream area of electronic unit pump[J].Transactions of the Chinese Society for Agricultural Machinery,2016,47(5):360-365.
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[24] COUTIER-DELGHOSA O,PATELLA R F,REBOUD J L.Evaluation of the turbulence model influence on the numerical simulations of unsteady cavitation[J].Journal of Fluids Engineering,2003,125(1):38-45.
[25] 张博,王国玉,张淑丽,等.修正的RNG κ-ε模型在云状空化流动计算中的应用评价[J].北京理工大学学报,2008,28(12):1065-1069.ZHANG Bo,WANG Guoyu,ZHANG Shuli,et al.Evaluation of a modified RNG κ-ε model for computations of cloud cavitating flows[J].Transactions of Beijing Institute of Technology,2008,28(12):1065-1069.
[26] HE Z,CHEN Y,LENG X,et al.Experimental visualization and LES investigations on cloud cavitation shedding in a rectangular nozzle orifice[J].International Communications in Heat & Mass Transfer,2016,76:108-116.
[27] CHEN G H,WANG G Y,HU C L,et al.Observations and measurements on unsteady cavitating flows using a simultaneous sampling approach[J].Experiments in Fluids,2015,56(2):1-11.
[2] LI B B,LI W H,JIAO M,et al.Analysis of cavitation characteristics in throttle valve with different structure parameters[J].Journal of Mechanics in Medicine & Biology,2016,17(3):1750047.
[3] 李贝贝,刘秀梅,龙正,等.基于Fluent的节流阀油液空化流场数值分析[J].振动与冲击,2015,34(21):54-58.LI Beibei,LIU Xiumei,LONG Zheng,et al.Simulation and analysis for cavitation flow field in a throttle valve based on Fluent[J].Journal of Vibration and Shock,2015,34(21):54-58.
[4] 陆亮.液压节流阀中的空化流动与噪声[D].杭州:浙江大学,2012.
[5] 王松林,谭磊,王玉川.离心泵瞬态空化流动及压力脉动特性[J].振动与冲击,2013,32(22):168-173.WANG Songlin,TAN Lei,WANG Yuchuan.Characteristics of transient cavitation flow and pressure fluctuation for a centrifugal pump[J].Journal of Vibration and Shock,2013,32(22):168-173.
[6] 黄彪,王国玉,张博,等.空化模型在非定常空化流动计算的应用评价与分析[J].船舶力学,2011,15(11):1195-1202.HUANG Biao,WANG Guoyu,ZHANG Bo,et al.Assessment of cavitation models for computation of unsteady cavitating flows[J].Journal of Ship Mechanics,2011,15(11):1195-1202.
[7] 宋宇,曹树良.考虑不可凝结气体的空化流模型及数值模拟[J].排灌机械工程学报,2012,30(1):1-5.SONG Yu,CAO Shuliang.Cavitation model with non-condensable gas effect and its numerical simulation[J].Journal of Drainage & Irrigation Machinery Engineering,2012,30(1):1-5.
[8] 刘德民,刘树红,吴玉林,等.基于修正空化质量传输方程的水轮机空化的数值模拟[J].工程热物理学报,2011,32(12):2048-2051.LIU Demin,LIU Shuhong,WU Yulin,et al.Numerical simulation the cavitation on francis turbine based on the modified mass transfer equation[J].Journal of Engineering Thermophysics,2011,32(12):2048-2051.
[9] 龙新平,程茜,韩宁.射流泵空化影响因素的数值分析[J].应用基础与工程科学学报,2009,17(3):461-469.LONG Xinping,CHENG Qian,HAN Ning.Numerical Analysis on the Factors Affecting Cavitation within Jet Pumps[J].Journal of Basic Science & Engineering,2009,17(3):461-469.
[10] 王新昶,孙方宏,孙乐申,等.高压差高固含量减压阀的仿真优化设计[J].上海交通大学学报,2011,45(11):1597-1601.WANG Xinchang,SUN Fanghong,SUN Leshen,et al.Simulation and optimal design of high-pressure-differential and high-solid-phase relief valves[J].Journal of Shanghai Jiaotong University,2011,45(11):1597-1601.
[11] 肖鑫.调节阀流场分析与结构优化研究[D].哈尔滨:哈尔滨工程大学,2013.
[12] TAN L,ZHU B S,CAO S L,et al.Numerical simulation of unsteady cavitation flow in a centrifugal pump at off-design conditions[J].Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science,2014,228(11):1994-2006.
[13] TAN L,ZHU B,WANG Y,et al.Numerical study on characteristics of unsteady flow in a centrifugal pump volute at partial load condition[J].Engineering Computations:International Journal for Computer-Aided Engineering and Software,2015,32(6):1549-1566.
[14] CHEN Q,STOFFEL B.CFD Simulation of a Hydraulic Servo Valve With Turbulent Flow and Cavitation[C]// ASME/JSME 2004 Pressure Vessels and Piping Conference,2004:710-712.
[15] YE Y,YIN C B,LI X D,et al.Effects of groove shape of notch on the flow characteristics of spool valve[J].Energy Conversion and Management,2014,86:1091-1101.
[16] ZHENG Z,OU G,YE H,et al.Investigation on failure process and structural optimization of a high pressure letdown valve[J].Engineering Failure Analysis,2016,66:223-239.
[17] LIANG J,LUO X,LIU Y,et al.A numerical investigation in effects of inlet pressure fluctuations on the flow and cavitation characteristics inside water hydraulic poppet valves[J].International Journal of Heat & Mass Transfer,2016,103:684-700.
[18] PASSANDIDEH-FARD M,MOIN H.A computational study of cavitation in a hydraulic poppet valve[C]// International Conference on Transport Phenomena in Multiphase Systems,2008.
[19] 陈庆光,吴玉林,刘树红,等.轴流式水轮机全流道内非定常空化湍流的数值模拟[J].机械工程学报,2006,42(6):211-216.CHEN Qingguang,WU Yulin,LIU Shuhong,et al.Numerical simulation of unsteady cavitating turbulent flow in the whole flow passage of a kaplan turbine[J].Chinese Journal of Mechanical Engineering,2006,42(6):211-216.
[20] 偶国富,饶杰,章利特,等.煤液化高压差调节阀空蚀/冲蚀磨损预测[J].摩擦学学报,2013,33(2):155-161.OU Guofu,RAO Jie,ZHANG Lite,et al.Numerical investigation of cavitation erosion/solid particle erosion in high differential pressure control valves in coal liquefaction[J].Tribology,2013,33(2):155-161.
[21] 麻斌,高莹,刘宇,等.不凝性气体及湍流扰动对喷嘴孔内空化现象的影响[J].农业机械学报,2017,48(4):342-348.MA Bin,GAO Ying,LIU Yu,et al.Effects of noncondensable gases and turbulent fluctuations on cavitation phenomenon in injector nozzle[J].Transactions of the Chinese Society for Agricultural Machinery,2017,48(4):342-348.
[22] 安晓东,刘兴华,孙柏刚,等.电控单体泵锥阀下游区域瞬态流场变化特性研究[J].农业机械学报,2016,47(5):360-365.AN Xiaodong,LIU Xinghua,SUN Baigang,et al.Change characteristics of transient flow field in poppet valve downstream area of electronic unit pump[J].Transactions of the Chinese Society for Agricultural Machinery,2016,47(5):360-365.
[23] LI H,KELECY F J,EGELJA-MARUSZEWSKI A,et al.Advanced computational modeling of steady and unsteady cavitating flows[C]// ASME 2008 International Mechanical Engineering Congress and Exposition.2008:413-423.
[24] COUTIER-DELGHOSA O,PATELLA R F,REBOUD J L.Evaluation of the turbulence model influence on the numerical simulations of unsteady cavitation[J].Journal of Fluids Engineering,2003,125(1):38-45.
[25] 张博,王国玉,张淑丽,等.修正的RNG κ-ε模型在云状空化流动计算中的应用评价[J].北京理工大学学报,2008,28(12):1065-1069.ZHANG Bo,WANG Guoyu,ZHANG Shuli,et al.Evaluation of a modified RNG κ-ε model for computations of cloud cavitating flows[J].Transactions of Beijing Institute of Technology,2008,28(12):1065-1069.
[26] HE Z,CHEN Y,LENG X,et al.Experimental visualization and LES investigations on cloud cavitation shedding in a rectangular nozzle orifice[J].International Communications in Heat & Mass Transfer,2016,76:108-116.
[27] CHEN G H,WANG G Y,HU C L,et al.Observations and measurements on unsteady cavitating flows using a simultaneous sampling approach[J].Experiments in Fluids,2015,56(2):1-11.