径向唇形密封的密封性能研究

发布时间：2018-04-10 17:23

本文选题：径向唇形密封 + 生热　；参考：《重庆大学》2012年硕士论文

【摘要】：密封系统可靠性影响着旋转机械的可靠性，而径向唇型密封是一种常见的重要密封。径向唇形密封失效原因有很多，主要与密封接触区域的生热和泵汲效应有关。密封的泵汲率并不是越高越好，因为唇口生热量可能也很高，密封性能仍然不佳。密封参数设计时，既要考虑各参数对生热和泵汲效应的单一影响，又需要综合考虑生热和泵汲效应对密封性能的影响，而此类研究缺乏。本文针对这一研究现状，以轴的微观往复运动机理为基础，并考虑抱轴力与唇口形变量之间的应变关系，建立密封区域的二维模型，分别利用理论分析和CFD数值模拟方法分析相关参数对密封性能的影响。理论分析结果表明，密封间隙内的压差作用才是影响泵汲效应的主要因素，微观往复运动对泵汲效应没有明显影响。转速提高后，泵汲率增大，但是唇口单位面积生热量和总生热量也都增加，密封性能不一定得到提高。当抱轴力增加时，生热量增加，泵汲率不变，密封性能下降，因此在满足跟随性的前提下，抱轴力应当尽量设计为较小值。随着材料杨氏模量的提高，泵汲率逐渐减小，总生热量不变，单位面积生热量增加，密封性能下降。随着唇口厚度增加，泵汲率逐渐增加，唇口总生热量不变，单位面积生热量减小，密封性能提高。轴径增加后，，轴表面的线速度增加，泵汲率显著提高，单位面积生热量和总生热量也同样增加很多。在设计密封唇角时，应该选取较小的空气侧唇角，并保持两侧唇角之差约为20～30°，这时唇口总生热量一定，泵汲率相对较高，密封性能良好。 CFD模拟结果表明，由偏心造成的周期性微观往复运动、转速和接触宽度对密封间隙及附近的压力分布有一定影响，且当接触宽度较大，偏心角度为1°时，泵汲率较高；当接触宽度较小，偏心角度为0.5～1°时，泵汲率较高。然而模拟所得泵汲率相对理论分析所得计算结果仍偏小，这也说明理论分析与模拟的结果具有一致性，即唇口的压力分布才是影响泵汲效应的主要因素，而微观往复运动对泵汲效应影响有限。
[Abstract]:The reliability of sealing system affects the reliability of rotating machinery, and radial lip seal is a common important seal.There are many reasons for the failure of radial lip seal, mainly related to heat generation and pump swabbing effect in seal contact area.Sealing pump swabbing rate is not as high as possible, because lip heat may also be high, sealing performance is still poor.In the design of sealing parameters, the single effect of each parameter on heat generation and pump swabbing effect should be considered, and the influence of heat generation and pump swabbing effect on sealing performance should be considered synthetically, but this kind of research is lacking.In this paper, based on the micro reciprocating mechanism of the shaft and considering the strain relationship between the axial holding force and the lip shape variables, a two-dimensional model of the sealing area is established.Theoretical analysis and CFD numerical simulation were used to analyze the influence of relevant parameters on sealing performance.The theoretical analysis results show that the pressure difference in the seal clearance is the main factor affecting the pump swabbing effect, but the micro reciprocating movement has no obvious effect on the pump swabbing effect.With the increase of rotational speed, the pump swabbing rate increases, but the heat generation and the total heat generation per unit area of the lip also increase, so the sealing performance is not necessarily improved.When the axial force increases, the heat generation increases, the pump swabbing rate remains unchanged, and the sealing performance decreases. Therefore, the axial holding force should be designed as small as possible under the premise of satisfying the following property.With the increase of Young's modulus, the pump swabbing rate decreases gradually, the total heat generation remains unchanged, the heat generation per unit area increases, and the sealing performance decreases.With the increase of the lip thickness, the pump swabbing rate increases gradually, the total heat generation of the lip is unchanged, the heat generation per unit area decreases, and the sealing performance is improved.With the increase of axis diameter, the linear velocity of the shaft surface increases, the pump swabbing rate increases significantly, and the heat generation per unit area and the total heat generation also increase a lot.When designing the seal lip angle, the air side lip angle should be chosen, and the difference between the two sides lip angle should be about 2030 掳. At this time, the total heat production of the lip is constant, the pump swabbing rate is relatively high, and the sealing performance is good.CFD simulation results show that the periodic micro-reciprocating motion caused by eccentricity, rotational speed and contact width have certain influence on the seal clearance and the pressure distribution nearby, and when the contact width is large and the eccentric angle is 1 掳, the pump swabbing rate is higher.When the contact width is small and the eccentric angle is 0.5 掳, the pump swabbing rate is higher.However, the calculated results of the simulated pump swabbing rate are still relatively small compared with the theoretical analysis, which also shows that the theoretical analysis is consistent with the simulated results, that is, the pressure distribution of the lip is the main factor affecting the pump swabbing effect.Microcosmic reciprocating motion has limited effect on pump swabbing effect.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH136

【参考文献】