溶胀对螺杆泵定转子过盈量的影响分析
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摘要
常规采油螺杆泵在井下环境中,定子橡胶因溶胀会产生不均匀变形,这是设计定转子不可忽略的影响因素。为了分析不同头数定转子的溶胀变形规律及溶胀率和过盈量间的合理配合关系,定子橡胶材料选用Mooney-Rivlin模型,转子处理成刚体,建立了两头、三头、四头和五头螺杆泵定转子刚柔接触有限元模型。根据溶胀与温胀定子变形的相似特点,采用温度比拟法模拟溶胀,研究了定子溶胀变形规律及溶胀对接触压力的影响。研究结果表明:考虑密封要求,当溶胀率小于2.5%时,设计的过盈量应为正值,齿凹处接触压力较大;溶胀率大于2.5%时,设计的过盈量应为负值,齿凸处接触压力较大;当定子头数较多时,溶胀变形量小且齿凹处的接触压力小,对溶胀的适应性强;国内常用的定子橡胶在井下的溶胀率为3.0%~5.0%,过盈量应取负值。在现场应用中,可根据试验测定的定子橡胶溶胀率,对应找到合理的配合过盈量,这对定转子初始过盈量的设计具有很好的指导意义。
In downhole environment,the conventional oil progressing cavity pump may experience uneven deformation of stator rubber owing to swelling,which is an indispensable factor in stator and rotor design. In order to analyze the swelling deformation of the stator and rotor with different lobes,as well as the reasonable relationship between the swelling rate and the interference,the finite element models for rigid-flexible contact of the stator and rotor with two,three,four and five lobes are established by adopting the Mooney-Rivlin model for stator rubber material and the rigid body for rotor. According to the similar characteristics of the swelling deformation and thermoexpansion of the stator,the swelling is simulated by the temperature analogy method. The swelling deformation of the stator and its effect on the contact pressure are studied. The research results showed that,considering the sealing requirements,when the swelling ratio is less than 2. 5%,the designed interference should be positive and the contact pressure at the tooth concave is relatively large. When the swelling ratio is higher than 2. 5%,the designed interference should be negative. The contact pressure at the tooth convex is relatively large. When the number of stator lobes is large,the swelling deformation becomes small and the contact pressure at the tooth concave is small,resulting in strong adaptability to swelling. The swelling rate of domestic commonly used stator rubber is 3. 0% ~5. 0%,a negative interference value should be taken. In field application,proper interference should be determined based on the stator rubber swelling rate attained by test,which provides a very good guiding significance for the design of the initial interference of the stator and rotor.
In downhole environment,the conventional oil progressing cavity pump may experience uneven deformation of stator rubber owing to swelling,which is an indispensable factor in stator and rotor design. In order to analyze the swelling deformation of the stator and rotor with different lobes,as well as the reasonable relationship between the swelling rate and the interference,the finite element models for rigid-flexible contact of the stator and rotor with two,three,four and five lobes are established by adopting the Mooney-Rivlin model for stator rubber material and the rigid body for rotor. According to the similar characteristics of the swelling deformation and thermoexpansion of the stator,the swelling is simulated by the temperature analogy method. The swelling deformation of the stator and its effect on the contact pressure are studied. The research results showed that,considering the sealing requirements,when the swelling ratio is less than 2. 5%,the designed interference should be positive and the contact pressure at the tooth concave is relatively large. When the swelling ratio is higher than 2. 5%,the designed interference should be negative. The contact pressure at the tooth convex is relatively large. When the number of stator lobes is large,the swelling deformation becomes small and the contact pressure at the tooth concave is small,resulting in strong adaptability to swelling. The swelling rate of domestic commonly used stator rubber is 3. 0% ~5. 0%,a negative interference value should be taken. In field application,proper interference should be determined based on the stator rubber swelling rate attained by test,which provides a very good guiding significance for the design of the initial interference of the stator and rotor.
引文
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[10]张强,高磊,刘昱良,等.基于温度比拟法的橡胶定子溶胀影响密封性能的研究[J].润滑与密封,2017,42(4):75-79,100.ZHANG Q,GAO L,LIU Y L,et al.Research on rubber stator sealing performance affected by swelling based on temperature analogy method[J].Lubrication Engineering,2017,42(4):75-79,100.
[11]韩国有,赵毅,杜秀华.采油螺杆泵三维有限元模型分析[J].东北石油学院学报,2010,34(5):110-113.HAN G Y,ZHAO Y,DU X H.Analysis of three dimensional finite element model for oil extraction progressing cavity pump[J].Journal of Daqing Petroleum Institute,2010,34(5):110-113.
[2]魏纪德,吴文祥,曾艳.螺杆泵定子橡胶溶胀对容积效率的影响及对策[J].石油机械,2005,33(4):16-18.WEI J D,WU W X,ZENG Y.Influence of stator rubber plumping of screw pumps on volume efficiency and countermeasures[J].China Petroleum Machinery,2005,33(4):16-18.
[3]陈勇,李萍.螺杆泵定子用丁腈橡胶溶胀性能的研究[J].橡胶科技市场,2008,6(12):21-23.CHEN Y,LI P.Swelling properties of nitrile rubberfor stator of screw pump[J].China Rubber Science and Technology Market,2008,6(12):21-23.
[4]张劲,张士诚.常规螺杆泵定子有限元求解策略[J].机械工程学报,2004,40(5):189-193.ZHANG J,ZHANG S C.FEM analysis policy for a general screw-pump’s stator[J].Chinese Journal of Mechanical Engineering,2004,40(5):189-193.
[5]韩传军,张杰,刘洋.常规螺杆钻具定子衬套的热力耦合分析[J].中南大学学报(自然科学版),2013,44(6):2311-2317.HAN C J,ZHANG J,LIU Y.Thermal-structure coupling analysis for general stator lining of PDM[J].Journal of Central South University(Science and Technology),2013,44(6):2311-2317.
[6]祝效华,石昌帅,童华.静压、压差与泊松比对定子衬套变形的影响[J].西南石油大学学报(自然科学版),2010,32(6):175-179.ZHU X H,SHI C S,TONG H.Influence of static press,pressure difference and Poisson’s ratio on deformation of stator lining[J].Journal of Southwest Petroleum University(Science&Technology Edition),2010,32(6):175-179.
[7]叶卫东,杜秀华,宋玉杰,等.橡胶材料力学参数对螺杆泵密封性能的影响[J].润滑与密封,2008,33(10):70-72.YE W D,DU X H,SONG Y J,et al.The effects of rubber materials mechanical parameters on progressive cavity pump seal performance[J].Lubrication Engineering,2008,33(10):70-72.
[8]侯宇.螺杆泵定转子合理过盈量确定方法研究[D].大庆:东北石油大学,2011.HOU Y.A Study on the rational interference fit between rotor and stator of progressing cavity pump[D].Daqing:Northeast Petroleum University,2011.
[9]李晓芳,孙春龙,李强.螺杆泵定转子过盈接触三维有限元分析[J].润滑与密封,2008,33(10):64-65,48.LI X F,SUN C L,LI Q.3D-FEM analysis of stator-rotor interference fit contact of progressing cavity pump[J].Lubrication Engineering,2008,33(10):64-65,48.
[10]张强,高磊,刘昱良,等.基于温度比拟法的橡胶定子溶胀影响密封性能的研究[J].润滑与密封,2017,42(4):75-79,100.ZHANG Q,GAO L,LIU Y L,et al.Research on rubber stator sealing performance affected by swelling based on temperature analogy method[J].Lubrication Engineering,2017,42(4):75-79,100.
[11]韩国有,赵毅,杜秀华.采油螺杆泵三维有限元模型分析[J].东北石油学院学报,2010,34(5):110-113.HAN G Y,ZHAO Y,DU X H.Analysis of three dimensional finite element model for oil extraction progressing cavity pump[J].Journal of Daqing Petroleum Institute,2010,34(5):110-113.