| As a new type of non-contact mechanical seal,the diffuser self-pumping mechanical seal has self-lubricating and self-cleaning characteristics,and effectively improves the opening force of the end face.However,due to the large number of end face structural parameters,traditional modeling methods will consume a lot of time when analyzing the influence of structural parameters on sealing performance through numerical simulation.When designing and selecting the rotating ring end face of a diffuser self-pumping mechanical seal,consideration should be given to the requirements of opening force and leakage rate.The interaction between the structural parameters of the seal end face makes its sealing mechanism more complex.This article took the diffuser self-pumping mechanical seal as the object.Firstly,a three-dimensional parametric modeling was conducted on its rotating ring end face and fluid calculation domain.Then,Fluent software was used to explore the single factor influence law and multi factor interaction of its main structural parameters on sealing performance through numerical simulation methods.Finally,uniform experiments were designed and multiple regression analysis was conducted,with leakage rate and opening force as the target parameters.A prediction model for the sealing performance of the diffuser self-pumping mechanical seal was established,and a multi-objective optimization method was used to find the optimal combination of rotating ring end face structural parameters for sealing performance.The main research work and conclusions of this article are as follows:1.Using Visual Basic programming and size driven method for secondary development of Solid Works software.A groove drawing method based on parameter equation driven logarithmic helix was proposed,and three-dimensional parametric modeling was performed on the rotating ring end face and fluid calculation domain of the diffuser self-pumping mechanical seal.This made the built model closer to the real structure,and users can directly modify the sealing structure parameters through the human-machine interaction window,Compared with traditional modeling methods,it greatly reduces modeling time,improves numerical simulation efficiency and accuracy.2.The key research structures were determined to be spiral grooves and diffuser ring grooves.The fluid calculation domain obtained from parameterized modeling was meshed using ICEM and the grid independence was verified.The boundary conditions and solver were set using Fluent software to study the single factor influence of the spiral groove length and diffuser ring groove width on the sealing performance of the diffuser self-pumping mechanical seal at different rotational speeds.The results show that as the spiral groove becomes longer,the opening force and leakage rate of the sealing end face will increase;As the diffuser groove widens,the opening force will significantly increase,while the leakage rate will increase slowly.3.A test table using the response surface method was designed and corresponding numerical simulation experiments were conducted to explore the interaction of various structural parameters on sealing performance.The results show that the spiral groove length and diffuser ring groove width have a significant impact on leakage rate,while the spiral groove length,diffuser ring groove width,spiral groove depth,diffuser ring groove depth,and width ratio of groove to diffuser ring have a significant impact on opening force;The analysis of the interaction effect shows that the interaction between spiral groove length and diffuser ring groove width has a significant impact on the leakage rate.The interaction between spiral groove length and diffuser ring groove depth,between spiral groove length and diffuser ring groove width,between spiral groove length and width ratio of groove to diffuser ring,between diffuser ring groove width and depth,between diffuser ring groove width and width ratio of groove to diffuser ring,between spiral groove depth and diffuser ring groove depth,between diffuser ring groove depth and width ratio of groove to diffuser ring have significant impact on the opening force.And analyzed the impact of the interaction of seven sets of structural parameters on the sealing performance one by one.4.Selecting five structural parameters,namely the inner diameter of the sealing ring,sealing dam length,spiral groove length,diffuser ring groove width,and spiral groove depth,a uniform test table was designed and numerically simulated.Performance prediction models for leakage rate and opening force were established using the method of quadratic polynomial stepwise regression.The NSGA2 multi-objective optimization method was used to avoid leakage while obtaining a large opening force as the goal,and the Pareto optimal solution set was obtained,The optimized structure significantly improves the opening force and reduces the leakage rate.Then,the weighted TOPSIS decision method was used to screen the optimal solution set and obtain the optimal results for different sizes under zero leakage conditions.As the inner diameter size increases,sealing dam length,spiral groove length,and diffuser ring groove width all correspondingly increase.The depth of the spiral groove becomes shallower,and there is a 2:1.5:1 ratio relationship between sealing dam length,spiral groove length,and diffuser ring groove width.Evaluation of the optimal sealing performance corresponding to different leakage rate weights shows that as the leakage rate weight increases,the sealing dam length,spiral groove length,and diffuser ring groove width all show a decreasing trend.The ratio of sealing dam length to diffuser ring groove width is between 1.46 and 2.01,and the ratio of spiral groove length to diffuser ring groove width is between 1.32 and 1.86,indicating the optimal sealing performance.The optimized values of leakage rate and opening force verified have little error compared to the simulated values,providing a reference for the selection and further research of diffuser self-pumping mechanical seal. |
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