槽口深度对U型节流阀空化流场的影响
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摘要
采用数值计算的方法对U型节流阀内部流场进行了研究,分析了不同节流槽深度对节流阀内部油液压力场、速度场及空化区域的影响.研究结果表明:流道内压力较大区域位于上游流道,压力较小区域位于下游流道;U型节流槽是压力及速度突变区,在节流槽出口处出现压力骤降并在节流阀口处形成高速射流;在相同工况下,随着节流槽深度的增加,槽内流量增多,迫使油液急速流过节流口,从而造成射流方向发生改变,且高速射流的角度呈现不断减小的趋势,但是油液最大流速逐渐增大.节流槽出口靠近阀腔壁面处产生空化,且随着槽口深度加深时,节流槽内部压力恢复变慢,空化区域的面积逐渐增大,且径向截面空化较强的区域逐渐向节流槽中心扩展.因此,合理地控制U形节流槽的深度或增加节流槽内部阻力,可以有效地抑制空化发生.
A CFD numerical calculation model was established in order to study the flow field inside U-shaped throttle valve. The velocity,pressure drop and cavitation region in throttle with different groove depths were also obtained. The numerical results show that the maximum pressure is located at the upstream of the flow channel and the minimum pressure is located at the downstream of the flow channel. The pressure drops a lot and a high-speed jet forms when the fluid passes through the throttle outlet. Under the same working conditions,with the increase of groove depth,the flow in the notch increases. This situation forces the oil to flow rapidly through the orifice,which results in a change in the direction of the jet. The angle of high-speed jet shows a decreasing trend,but the maximum flow rate of oil gradually increases. At the outlet of the throttle groove,cavitation occurs near the wall of the valve cavity,and with the depth of the groove increasing,the internal pressure of the throttle notch is reco-vered slowly,the cavitation area increases gradually,and the strong cavitation area in the radial section gradually expands toward the center of the throttling tank. Therefore,a reasonable control of the Ugroove depth or increasing the internal resistance of the throttle can effectively inhibit the occurrence of cavitation.
A CFD numerical calculation model was established in order to study the flow field inside U-shaped throttle valve. The velocity,pressure drop and cavitation region in throttle with different groove depths were also obtained. The numerical results show that the maximum pressure is located at the upstream of the flow channel and the minimum pressure is located at the downstream of the flow channel. The pressure drops a lot and a high-speed jet forms when the fluid passes through the throttle outlet. Under the same working conditions,with the increase of groove depth,the flow in the notch increases. This situation forces the oil to flow rapidly through the orifice,which results in a change in the direction of the jet. The angle of high-speed jet shows a decreasing trend,but the maximum flow rate of oil gradually increases. At the outlet of the throttle groove,cavitation occurs near the wall of the valve cavity,and with the depth of the groove increasing,the internal pressure of the throttle notch is reco-vered slowly,the cavitation area increases gradually,and the strong cavitation area in the radial section gradually expands toward the center of the throttling tank. Therefore,a reasonable control of the Ugroove depth or increasing the internal resistance of the throttle can effectively inhibit the occurrence of cavitation.
引文
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[14]张晓俊,权龙,赵斌.内流式滑阀壁面压力分布可视化计算及试验验证[J].机械工程学报,2016,52(14):196-203.ZHANG Xiaojun,QUAN Long,ZHAO Bin.Visualization calculation and experimental verification of steady axial flow force on the converged flow sliding valve[J].Journal of mechanical engineering,2016,52(14):196-203.(in Chinese)
[15]冀宏.液压阀芯节流槽气穴噪声特性的研究[D].杭州:浙江大学,2004.
[16]LIANG Jian,LUO Xiaohui,LIU Yinshui,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.
[17]杜学文,邹俊,傅新,等.节流槽结构对气穴噪声的影响[J].浙江大学学报(工学版),2007,41(3):456-460.DU Xuewen,ZOU Jun,FU Xin,et al.Effect of throttling grooves structure on cavitation noise[J].Journal of Zhejiang University(engineering science),2007,41(3):456-460.(in Chinese)
[18]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.(in Chinese)
[19]张健,姜继海,白云峰,等.气穴中液压油温度随气泡膨胀变化规律[J].哈尔滨工程大学学报,2015,36(4):539-543.ZHANG Jian,JIANG Jihai,BAI Yunfeng,et al.Change law of hydraulic oil temperature with bubble growth in cavitation[J].Journal of Harbin Engineering University,2015,36(4):539-543.(in Chinese)
[20]高红.溢流阀阀口气穴与气穴噪声的研究[D].杭州:浙江大学,2003.
[21]冀宏,王东升,刘小平,等.滑阀节流槽阀口的流量控制特性[J].农业机械学报,2009,40(1):198-202.JI Hong,WANG Dongsheng,LIU Xiaoping,et al.Flow control characteristic of the orifice in spool valve with notches[J].Transactions of the CSAM,2009,40(1):198-202.(in Chinese)
[2]WANG Zhaoqiang,GU Linyi,JI Hong,et al.Flow field simulation and establishment for mathematical models of flow area of spool valve with sloping U-shape notch machined by different methods[J].Journal of Central South University,2014,21(1):140-150.
[3]LIU Xiumei,HE Jie,ZHAO Jiyun,et al.Biofluid flow through a throttle valve:a computational fluid dynamics study of cavitation[J].Journal of mechanics in medicine&biology,2016,16(3):1650034.
[4]谭磊,曹树良,桂绍波,等.绕水翼空化流动的数值模拟[J].清华大学学报(自然科学版),2010,50(7):1058-1062.TAN Lei,CAO Shuliang,GUI Shaobo,et al.Numerical simulation of cavity flow around a hydrofoil[J].Journal of Tsinghua University(natural science edition),2010,50(7):1058-1062.(in Chinese)
[5]吴晓明,要继业,李伟,等.U+K节流槽滑阀的数值模拟[J].流体传动与控制,2010(5):13-15.WU Xiaoming,YAO Jiye,LI Wei,et al.The numerical simulation of spool valve with U+K notches[J].Fluid power transmission&control,2010(5):13-15.(in Chinese)
[6]ZHENG Zhijian,OU Guofu,YE Haojie,et al.Investigation on failure process and structural optimization of a high pressure letdown valve[J].Engineering failure analysis,2016,66:223-239.
[7]冀宏,傅新,杨华勇,等.节流槽型阀口噪声特性试验研究[J].机械工程学报,2004,40(11):42-46.JI Hong,FU Xin,YANG Huayong,et al.Experimental study on noise characteristics of groove-type orifices[J].Chinese journal of mechanical engineering,2004,40(11):42-46.(in Chinese)
[8]RITO G D.Experiments and CFD simulations for the characterisation of the orifice flow in a four-way servo valve[J].International journal of fluid power,2007,8(2):37-46.
[9]HUANG Hao,LEI Huihu.Modeling and simulation of flow field of main spool in servo valve[C]//International Conference on Electronic and Mechanical Engineering and Information Technology.Harbin,China:[s.n.],2011:867-870.
[10]DENG Jian,PAN Dingyi,XIE Fangfang,et al.Numerical investigation of cavitation flow inside spool valve with large pressure drop[C]//9th International Symposium on Cavitation.Lausanne,Switzerland:[s.n.],2015:012067.
[11]YE Yi,YIN Chenbo,LI Xingdong,et al.Effects of groove shape of notch on the flow characteristics of spool valve[J].Energy conversion&management,2014,86(5):1091-1101.
[12]BORGHI M,MILANI M,PAOLUZZI R.Influence of notch shape and number of notches on the metering characteristics of hydraulic spool valves[J].International journal of fluid power,2005,6(2):5-18.
[13]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.(in Chinese)
[14]张晓俊,权龙,赵斌.内流式滑阀壁面压力分布可视化计算及试验验证[J].机械工程学报,2016,52(14):196-203.ZHANG Xiaojun,QUAN Long,ZHAO Bin.Visualization calculation and experimental verification of steady axial flow force on the converged flow sliding valve[J].Journal of mechanical engineering,2016,52(14):196-203.(in Chinese)
[15]冀宏.液压阀芯节流槽气穴噪声特性的研究[D].杭州:浙江大学,2004.
[16]LIANG Jian,LUO Xiaohui,LIU Yinshui,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.
[17]杜学文,邹俊,傅新,等.节流槽结构对气穴噪声的影响[J].浙江大学学报(工学版),2007,41(3):456-460.DU Xuewen,ZOU Jun,FU Xin,et al.Effect of throttling grooves structure on cavitation noise[J].Journal of Zhejiang University(engineering science),2007,41(3):456-460.(in Chinese)
[18]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.(in Chinese)
[19]张健,姜继海,白云峰,等.气穴中液压油温度随气泡膨胀变化规律[J].哈尔滨工程大学学报,2015,36(4):539-543.ZHANG Jian,JIANG Jihai,BAI Yunfeng,et al.Change law of hydraulic oil temperature with bubble growth in cavitation[J].Journal of Harbin Engineering University,2015,36(4):539-543.(in Chinese)
[20]高红.溢流阀阀口气穴与气穴噪声的研究[D].杭州:浙江大学,2003.
[21]冀宏,王东升,刘小平,等.滑阀节流槽阀口的流量控制特性[J].农业机械学报,2009,40(1):198-202.JI Hong,WANG Dongsheng,LIU Xiaoping,et al.Flow control characteristic of the orifice in spool valve with notches[J].Transactions of the CSAM,2009,40(1):198-202.(in Chinese)