ISSN   1004-0595

CN  62-1224/O4

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基于平均膜厚和压力流量因子的机械密封泄漏分形模型

Leakage Fractal Model of Mechanical Seals Based on Average Film Thickness and Pressure Flow Rate Factor

  • 摘要: 研究接触式机械密封端面泄漏模型建立问题. 采用分形参数表征机械密封端面形貌,通过引入压力流量因子来反映实际粗糙表面对泄漏通道的影响,推导出了压力流量因子的分形表达式,建立了基于平均膜厚和压力流量因子的泄漏分形模型. 通过理论计算对机械密封泄漏率的影响因素进行了分析,并在自制的试验装置上对2套B104a-70型机械密封进行了试验,试验密封流体为20 ℃清水,压力为0.5 MPa,转速为2 900 r/min,弹簧比压分别为0.15和0.30 MPa. 研究结果表明:泄漏率随着弹簧比压的增大略有下降,随着密封流体压力及转速的增大而增大,且端面越粗糙增大的幅度越大;当端面较粗糙时,泄漏率随着端面分形维数的增大或特征尺度系数的减小而迅速减小,而当端面较光滑时,泄漏率的变化很小;泄漏率的理论计算值与试验值吻合较好,特别是在进入正常磨损阶段后相差很小.

     

    Abstract: Leakage model for contact mechanical seals was established. Using fractal parameters characterizing surface topography and introducing the pressure flow rate factor reflecting actual rough surface on leakage passage, fractal expressions of average film thickness and pressure flow rate factor were derived, and leakage fractal model based on average film thickness and pressure flow rate factor was established. Influence factors of leakage rate for mechanical seal were analyzed by theoretical calculation, and two sets of B104a-70 mechanical seals tests were made on the self-designed mechanical seal testing device. Test sealant was 20 ℃ water. Test pressure was 0.5 MPa. Rotating speed was 2 900 r/min. Spring pressures were 0.15 MPa and 0.30 MPa. Results show that leakage rate decreased slightly with the increasing spring pressure, and it increased with the increasing sealant pressure and rotating speed, and end face was more coarser, the amplitude of increasing was more larger. Leakage rate decreased rapidly with the increasing fractal dimension or with the decreasing characteristic length scale when the surface was coarser, while leakage rate changed little when the surface was smoother. The theoretical calculated values of leakage rate were consistent with the experimental values well, especially in the normal wearing stage.

     

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