Theoretical And Experimental Investigation On Mechanical Face Seal Performance Textured With Typical Surface Texture Patterns

The wear and leakage increase dramatically while the mechanical face seals operate under high environmental temperature,high medium pressure and high interfacial sliding speed.Lots of researches have been conducted to improve sealing performance by fabricating certain texture patterns with defined shapes,sizes and arrangements on mechanical face seals.Nowadays,many studies have been conducted to improve mechanical face seal performance by typical surface texture patterns of microgrooves and microdimples.The selection of surface texture patterns is the first problem of surface texturing design for mechanical face seals.Nevertheless,no systematic study comparing the effect of microgrooves and microdimples on hydrodynamic performance and leakage performance synthetically appears to exist in open literatures.In order to enrich the surface texture research on mechanical face seals,comparative investigation of mechanical face seals textured with different texture patterns was studied in both theory and experiment in this paper.At first,a theoretical model textured with different patterns was developed in hydrodynamic lubrication region based on Reynolds equation.The“interaction effect”between two neighboring dimples was systematically studied.The effect of textural parameters and operating parameters on sealing performance such as the load carrying force,gas film stiffness and gas leakage was investigated.Two property-evaluating parameters were defined and comparative analysis of different seal parameters between microgrooves and microdimples was presented.Then,the sealing experiments were designed and carried out according to the analytical results.The experimental results were compared with the theoretical analysis and the conclusions can be shown as follow:The results obtained from the research on“interaction effect”of adjacent texture showed that the pressure distribution presented periodic trend in the radial direction,but the value showed a nonlinear increment.In the circumferential direction,the pressure distribution had the same behavior,but the maximum and minimum pressure values of different columns were different and the location of the maximum and minimum pressure values had a small deviation.The results obtained from the theoretical research about the differences of sealing performance of mechanical face seals textured with different patterns showed that the improvement of hydrodynamic performance of surface texture was always companied with the increase of leakage.Area density,S_p was an important parameter.In the research,microdimples with a low area density could obtain higher property-evaluating parameters,but when the area density was higher than 10%,microgrooves yield better sealing performance.An optimal texture depth of about 3?m could be found for best seal performance for each individual texture pattern.It may be an important means to generate self-pumping capacity that could pump sealing medium from seal chamber to seal surface by the adjustment and optimization of inclination angle of surface texture.A small clearance?h₀<3?m?was helpful to increase the load carrying force,gas film stiffness and decrease the gas leakage.The load carrying force and gas film stiffness increased with increasing the pressure ratio and rotation speed,but it was often companied with the increase of leakage especially under the conditions of lager pressure ratio and higher rotation speed.The results obtained from the experimental research about the differences of sealing performance of mechanical face seals textured with different patterns showed that an optimal area density of11%-16%can be obtained for the lowest average friction coefficient for each individual texture pattern and the result showed a good correlation with it obtained from the theoretical analysis.In the experiment,sealing surface textured with microgrooves with a low area density?S_p<10%?had lower average friction coefficient and leakage rate,but when the area density was larger than 10%,the surface textured with microdimples had.For all selected texture patterns,textured surface with texture depth of 5?m presented optimum friction reduction and stable leakage rate.Among the pattern of microgrooves and microdimples selected in the experimental study,tribological and sealing performances of mechanical seals can be improved by the adjustment and optimization of inclination angle.The optimal rang of inclination angle was 30°-45°for all texture shapes.