Groove Design And Performance Study Of Liquid Film Seal Based On Bat Wings

Because of outstanding working performance(extremely low leakage rate,good lubricating property,stability and self-regulation ability,etc.)and long service life,liquid film seals have broad prospects for development in petrochemical,aerospace,ship and automobile industries.However,due to the changing working environment and conditions,there are still some problems(such as poor high-speed stability,medium phase transition,inadequate lowspeed opening characteristics,and serious wear and tear)in application.In order to alleviate the existing problems,various end face structures have been developed,but the using effect is always unsatisfactory.In view of the above mentioned situation,a groove structure of liquid film seal for bat-wing was proposed based on the bionic design method in this paper,and the performance of bat-wing groove seal was studied by combining experimental research with numerical simulation.The main work and conclusions are described as follows.Firstly,a bat-wing type end-face structure of liquid film seal was constructed by using bat wings as bionic model,and the phenomenon observation and parameter measurement of the seal were carried out by the cavitation visual test device.After that,the performance difference between bat-wing groove seal and spiral groove seal under the same working conditions and different influence factors on sealing performance were discussed.At the same time,the groove structure was optimized.Next,the mechanical and thermal deformation mathematical model of friction pairs of bat-wing groove seal was established,and the deformation of friction pairs under different working conditions was investigated by using fluid-structure coupling algorithm.Finally,the influence of instantaneous change of working condition on sealing performance and system stability was analyzed based on the axial dynamic model and the film pressure control equation considering time term.The results show that,the cavitation mainly occurs at the leeward side of spiral groove inner diameter and the convergence of circular groove,and decreases with the increase of pressure difference and the decrease of rotational speed.The steady-state performance of batwing groove seal is better than that of spiral groove seal when the operating parameters such as rotational speed,differential pressure,film thickness and film temperature are the same.The whirling speed and direction of the seal ring have great influence on the overall performance of the seal.When the system runs at high speed,the whirl motion should be avoided as far as possible to prevent rubbing of parts.Different optimization objectives lead to different combinations of groove structural parameters,corresponding selection should be made according to specific requirements in actual production.The positions of maximum mechanical deformation and maximum thermal deformation are different,thermal deformation plays a dominant role in the total deformation,the deformation is closely related to the material of friction pairs and operating conditions,the larger the speed and pressure difference,the more serious the deformation is.When the working condition changes continuously,the instantaneous performance of the seal is that the opening force,leakage and cavitation increase sharply first and then remain stable while the friction torque decreases sharply and then restores stability,and it takes less time for opening force,leakage and friction torque to reach stability than cavitation rate.When the working condition changes sharply,the liquid film oscillation is serious and the system suffers a great impact.In order to ensure the stable operation of the seal,the large-scale speed regulation and pressure regulation should be avoided as far as possible.