Study On The Influence Of Vibration Characteristics Of Flexible Rotor On Liquid Film Seal

Due to the rapid development of rotating machinery in the direction of high power,when the rotor passes through the critical speed,it will produce more severe vibration,which is called flexible rotor.The vibration characteristics of flexible rotor have a great influence on the working performance of mechanical seal,and the sealing performance is an important factor affecting the performance and life of rotating machinery.In order to understand the influence of vibration characteristics of flexible rotor on the performance of liquid film seal,theoretical research and numerical calculation methods are used to study the problem.The main work and conclusions are described as follows:Firstly,the three-dimensional model of the multi disk rotor is established,and the modal analysis of the rotor is carried out by using ANSYS Workbench finite element analysis software,then the critical speed and vibration mode diagram of the rotor are solved;according to the vibration mode diagram of the rotor,the motion state of the dynamic ring of the mechanical seal during vibration is analyzed:the eccentric,inclined and axial vibration of the dynamic ring.Secondly,the mathematical models of rotating ring eccentricity,rotating ring tilt and axial vibration are established respectively.For the liquid film seal with inner diameter slotting,the rotating ring eccentricity changes the area of the liquid film area between the seal ring end faces,the rotating ring tilt makes the liquid film thickness uneven distribution between the seal ring end faces,and the axial vibration of the rotating ring makes the liquid film in a dynamic change.Finally,the dynamic analysis of the model was carried out,and the film thickness variation formula was obtained.The film thickness variation was substituted into the Reynolds equation to solve the pressure distribution on the seal face and the steady-state performance parameters of the seal.The results show that:the eccentricity of the rotating ring leads to the uneven area of the groove,and the pressure of the sealing ring decreases with the decrease of the groove area;the existence of the inclination of the rotating ring makes the end pressure of the sealing ring asymmetric at both ends;at the initial stage of the axial vibration of the rotating ring,the end pressure of the sealing ring decreases sharply,and then maintains for a period of time after it reaches the minimum value,and the pressure also increases with the recovery of the liquid film thickness The recovery was stable.With the increase of the eccentricity of the rotating ring,the cavitation rate increases,and the influence on the leakage and friction torque tends to decrease;the inclination of the rotating ring will increase the opening force of the liquid film,and the cavitation rate will increase with the increase of the inclination,but the leakage rate does not change much,and the friction torque will increase slightly;when the rotating ring vibrates axially,the opening force,cavitation rate and friction torque of the liquid film will decrease to the maximum However,the minimum value ofΔh_max=1μm is higher than that of other vibration amplitudes,and the larger the amplitude is,the faster the time to reach the minimum value is.The leakage is the increase of vibration amplitude,the time point of leakage mutation is also in advance,and the change of leakage extreme value is also greater.