Study On Pumping Mechanism And Multi-Objective Optimization Of Reverse Herringbone Groove In Cylindrical Gas Seal

In aero-engine high speed fluid machinery,the floating adaptability of cylindrical gas seal has unique advantages in the field of aero-engine seal.Because it is difficult to process grooves in the sealing floating ring,domestic scholars put forward a new type of cylindrical air film seal by carving grooves on the side of the rotating shaft sleeve.With the sealing conditions of the cylindrical air film seal by grooving on the side of the shaft sleeve becoming more and more stringent in the practical application of engineering,the groove structure to obtain the optimal sealing performance has become a research focus.At present,the influence mechanism of the position characteristics and direction of the spiral groove on the sealing performance of the sleeve side grooving cylinder gas film has not been studied,and the influence mechanism of the reverse herringbone groove structure parameters on the sealing performance is not clear,and the key structural parameters that have the greatest influence on the sealing performance have not been extracted and multi-objective optimization has not been carried out.Based on the dynamic lubrication theory of sleeve side slotted cylinder air film seal,this paper explored the influence rule of groove spiral direction and position characteristics on sealing performance and conducted multi-objective optimization of reverse herringer groove parameters.The specific research contents are as follows:(1)By establishing the mathematical model of cylinder air film seal with grooving sleeve side,using finite difference method and overrelaxation iterative method to solve the gas film pressure distribution.The similarities and differences of groove seal mechanism with different position characteristics and spiral direction were expounded,and the response mechanism of performance parameters of different groove seal to operating parameters was explored,which provided theoretical reference for groove design and selection of cylindrical gas seal with grooving sleeve side.(2)According to the characteristics of sealing gas leakage controlled by countercurrent pumping of reverse herringer groove at high speed.The influence of structural parameters of reverse herringer groove on sealing performance was investigated.The single factor optimization method was used to obtain the optimal structural parameter combination of the reverse herringer groove,and the leakage control ability of the reverse pumping was evaluated.The results show that the sealing gas flow caused by the countercurrent pumping action of the reverse herringer groove can compensate the sealing gas leakage along the axial clearance caused by the differential pressure flow.By adjusting the structural parameters of the reverse herringer groove reasonably,the goal of zero leakage of the cylindrical gas seal with grooving sleeve side of the sleeve can be achieved.(3)By integrating Isight platform with MATLAB software,the original sample point data were obtained by using the optimal Latin hypercube experimental design,and the key groove parameters affecting the sealing performance of the reverse herringer groove were extracted.The original sample points were used to establish different types of approximate models and evaluate the prediction accuracy.The radial basis neural network approximate model satisfying the prediction accuracy was obtained and the multi-peak response of design variables and sealing performance parameters was investigated.Finally,the radial basis neural network approximation model was used to integrate NSGA-II multi-objective optimization algorithm module to optimize groove parameters and obtain pareto optimal solution.The sealing performance parameters of reverse herringer groove before and after single-factor optimization and multi-objective optimization were compared by numerical calculation.The research results show that the multi-objective optimization groove parameters can significantly improve the bearing capacity and sealing performance of the reverse herringer groove,and verify the feasibility of the approximate model integrated with NSGA-II multi-objective optimization algorithm based on Isight platform.The research results provided theoretical reference for the groove optimization design of the cylindrical gas seal with grooving sleeve side.