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  本文選題：徑向唇形密封 + 生熱　； 參考：《重慶大學》2012年碩士論文

【摘要】：密封系統(tǒng)可靠性影響著旋轉機械的可靠性，而徑向唇型密封是一種常見的重要密封。徑向唇形密封失效原因有很多，主要與密封接觸區(qū)域的生熱和泵汲效應有關。密封的泵汲率并不是越高越好，因為唇口生熱量可能也很高，密封性能仍然不佳。密封參數設計時，既要考慮各參數對生熱和泵汲效應的單一影響，又需要綜合考慮生熱和泵汲效應對密封性能的影響，而此類研究缺乏。本文針對這一研究現(xiàn)狀，以軸的微觀往復運動機理為基礎，并考慮抱軸力與唇口形變量之間的應變關系，建立密封區(qū)域的二維模型，分別利用理論分析和CFD數值模擬方法分析相關參數對密封性能的影響。 理論分析結果表明，密封間隙內的壓差作用才是影響泵汲效應的主要因素，微觀往復運動對泵汲效應沒有明顯影響。轉速提高后，泵汲率增大，但是唇口單位面積生熱量和總生熱量也都增加，密封性能不一定得到提高。當抱軸力增加時，生熱量增加，泵汲率不變，密封性能下降，因此在滿足跟隨性的前提下，抱軸力應當盡量設計為較小值。隨著材料楊氏模量的提高，泵汲率逐漸減小，總生熱量不變，單位面積生熱量增加，密封性能下降。隨著唇口厚度增加，泵汲率逐漸增加，唇口總生熱量不變，單位面積生熱量減小，密封性能提高。軸徑增加后，，軸表面的線速度增加，泵汲率顯著提高，單位面積生熱量和總生熱量也同樣增加很多。在設計密封唇角時，應該選取較小的空氣側唇角，并保持兩側唇角之差約為20～30°，這時唇口總生熱量一定，泵汲率相對較高，密封性能良好。 CFD模擬結果表明，由偏心造成的周期性微觀往復運動、轉速和接觸寬度對密封間隙及附近的壓力分布有一定影響，且當接觸寬度較大，偏心角度為1°時，泵汲率較高；當接觸寬度較小，偏心角度為0.5～1°時，泵汲率較高。然而模擬所得泵汲率相對理論分析所得計算結果仍偏小，這也說明理論分析與模擬的結果具有一致性，即唇口的壓力分布才是影響泵汲效應的主要因素，而微觀往復運動對泵汲效應影響有限。
[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 擄. 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 擄, the pump swabbing rate is higher.When the contact width is small and the eccentric angle is 0.5 擄, 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.
【學位授予單位】：重慶大學
【學位級別】：碩士
【學位授予年份】：2012
【分類號】：TH136

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