Studying On Leakage Model Of Contact Mechanical Seal Considering The Effect Of Surface Wettability

For a long time,the era of energy conservation,environmental protection and safe production has been required,and the leakage problem of mechanical seal has been a hot topic among scholars.Compared with the non-contact mechanical seal,the contact mechanical seal is not only simple in structure,low in manufacture,and convenient in maintenance,but also can obtain good sealing performance under the same production conditions.However,when calculating the leakage rate of contact mechanical seal,the existing theories and models are not perfect,so that the calculated value is larger or smaller than the actual value.In this thesis,therefore,the contact mechanical seal is taken as the research object to extract real seal interface as the sample.The leakage rate model based on the fractal theory of porous media is established.Considering the important role of surface wettability in microchannel flow,the influence of wettability on leakage rate is discussed.The main research tasks are summarized as follows:(1)The morphology data of the real seal end faces are collected and the contact model of asperities on two seal end faces was established.Using reverse engineering principle,the real rough surface of the seal end faces is generated,and the contact between the end faces of the mechanical seal is simplified as a contact between a rigid smooth plane and an elastic rough plane.(2)The change rules of surface morphology parameters under the different face pressure are revealed.Studying the change of surface morphology under the different face pressure by ANSYS,the parameters of porosity,fractal dimension and maximum pore diameter are calculated and their change rules are analyzed.(3)The microchannel with different surface contact angle is constructed to simulate the wettability effect in the actual leakage channel.The flow characteristics of fluid in microchannel are analyzed,introducing the impact factors of wettability on leakage rate,and the relationship between impact factors and contact angles is established.(4)Considering the effect of surface wettability on leakage rate,the theoretical model of contact mechanical seal leakage rate about the parameters such as surface contact angle,pressure,coefficient of viscosity,fractal dimension and maximum pore diameter is established based on modified Hagen-Poiseulle equation.This thesis studies the leakage of contact mechanical seal from a new point of view.The results are of great theoretical significance for the accurate calculation and prediction of leakage rate,the study of leakage suppression and the extension of its service life.