Study On Dynamic Characteristics Of Squeeze Film Damper Considering Oil-Air-Thermal Coupling

Squeeze Film Damper（SFD）has been widely applied to aero-engines due to its good damping effect,but,the dynamic properity of SFD is affect by the complex oil-air-thermal coupling.In order to clarify the effects of oil-air-thermal coupling on the dynamic characteristics of SFD,a three-dimensional fluid domain model of the SFD was established by CFX,and the numerical simulation analysis was based on transient time step solution method and dynamic mesh technique.The vapor cavitation of SFD was simulated based on the Z-G-B cavitation model,air ingestion of SFD was studied by adding additional mass cofficience and combine with the setting of boundary conditions and thermal effect of SFD was solved by the total thermal model,meantimes,the bidirectional excitation experiment research was carry out and veitify the accuracy of numerical simulation.The specific study content of this paper are follows:（1）Based on the theory analysis,by the help of theoretical formula of oil film pressure distribution of considering oil film inertial force,the mesh independence and the accuracy of numerical solution was veritified.（2）The characteristic of two phase was studied by the numerical simulation,and the influence of different working conditions,structural parameters and supply conditions on two phase are analysised.The results of study shows that the air ingestion will be suppressing the form of vapor cavitation,but vapor cavitation will promote the diffusion of air ingestion,when the two phenomena occur at the same time,the damper is prone to failure.（3）Considering the heat change caused by the viscous work of the SFD,the influence of different working conditions and structural parameters on the oil film temperature is analyzed.The study shows that the thermal effect of SFD will reduce the dynamic viscosity of oil,and resulting in a decrease in the damping of SFD.The formation of vapor cavitation is an endothermic process,so the vaporization degree and vaporization range of the vapor cavitation is serious by the thermal effect.Meantime,the thermal effect also increases the volume fraction and range of air ingestion.（4）The results of the experimental results have a good consistent with the simulation result considering oil-air-thermal coupling.With increasing precession frequency and eccentricity ratio,due to the existence of two phase and thermal effect,the effective squeezing aero of oil film is shrinking and peak pressure of oil film decrease resulting in oil film dampering shows a decrease trendency with the increase of procession frequency and eccentricity ratio.