發(fā)布時間：2018-07-24 08:58

【摘要】：對于介質為液體的機械端面密封，受密封環(huán)端面形貌的影響，在密封間隙局部會產(chǎn)生低壓區(qū)，當壓力低于工作溫度下液體的飽和蒸汽壓時，液體將發(fā)生汽化，形成氣泡，即發(fā)生了空化。為了分析密封的性能，必須考慮可能出現(xiàn)的空化現(xiàn)象。 對此，本課題提出了考慮空化效應的自由網(wǎng)格有限元算法，能夠適應任意端面構型的機械端面密封的計算，并給出一種非常規(guī)的有限元推導過程，能夠直接獲得求解域邊界的流量，特別適合機械密封的性能分析計算。該算法被證明高效穩(wěn)定，具有較高的可靠性，且推導過程嚴謹清晰，利于進一步擴展。 同時，基于MATLAB開發(fā)了一整套求解計算的程序，給出了完整的實現(xiàn)過程。該程序被證明具有適用性強、求解效率高等優(yōu)點。程序采用模塊化設計，便于進行二次開發(fā)，預置了5種密封端面結構以及2種邊界條件的求解模塊，引入了COMSOL Multiphysics軟件，通過API調(diào)用能夠實現(xiàn)多種功能，利于該程序向“流-固-熱”耦合分析進行擴展。對比了兩種空化邊界條件的計算，得知對于空化程度較高的模型，，JFO邊界條件的計算結果的可信度明顯高于雷諾邊界。而且預置的JFO邊界條件的計算模塊求解效率很高，求解時間甚至小于雷諾邊界條件，從而使JFO邊界條件能夠得到更廣泛的應用。另外，提出了一種新的斜直線槽密封結構，利用計算程序進行了性能分析。 進一步的，設計了一套全新的特殊的密封實驗臺，采用開放式設計，并采用透明材料制作其中一個密封環(huán)，因此能夠對密封間隙內(nèi)的流體進行直接觀測，并且能夠測量相關的性能參數(shù)。實驗證明斜直線槽密封在實驗的工況下發(fā)生了明顯的空化現(xiàn)象，空泡形狀與JFO邊界條件的計算結果十分吻合，顯示出JFO邊界條件的優(yōu)勢及必要性。
[Abstract]:For the mechanical end seal with liquid medium, due to the shape of the end surface of the seal ring, there will be a low pressure area in the seal clearance. When the pressure is below the saturated vapor pressure of the liquid at the working temperature, the liquid will vaporize and form a bubble. Cavitation occurs. In order to analyze the performance of seal, the cavitation phenomenon that may occur must be considered. In this paper, a free mesh finite element algorithm considering cavitation effect is proposed, which can be used for the calculation of mechanical end seal with arbitrary end configuration, and an unconventional finite element derivation process is given. The flow rate of the boundary can be obtained directly, which is especially suitable for the performance analysis of mechanical seals. The algorithm is proved to be efficient and stable with high reliability, and the derivation process is precise and clear, which is conducive to further expansion. At the same time, a whole set of program based on MATLAB is developed, and the complete realization process is given. The program has been proved to have strong applicability and high efficiency. The program is designed by modularization, which is convenient for secondary development. Five kinds of sealing end structure and two kinds of boundary conditions are preset. COMSOL Multiphysics software is introduced, and many functions can be realized by calling API. This program can be extended to the "fluid-solid-thermal" coupling analysis. By comparing the calculation results of two kinds of cavitation boundary conditions, it is found that the computational results of JFO boundary conditions with higher cavitation degree are more reliable than those with Reynolds boundary conditions. Moreover, the calculation module of preset JFO boundary condition is very efficient, and the solution time is even smaller than that of Reynolds boundary condition, so that the JFO boundary condition can be applied more widely. In addition, a new structure of oblique straight groove seal is proposed, and the performance is analyzed by computer program. Furthermore, a new set of special sealing test rig is designed, which is open design, and one of the sealing rings is made of transparent material, so that the fluid in the seal clearance can be observed directly. And can measure the related performance parameters. The experimental results show that the cavitation of oblique straight groove seal is obvious under the experimental condition, and the cavitation shape is in good agreement with the calculation result of JFO boundary condition, which shows the advantage and necessity of JFO boundary condition.
【學位授予單位】：清華大學
【學位級別】：碩士
【學位授予年份】：2011
【分類號】：TH136;O241.82

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