| The failure problems caused by the vibration of aero-engine blades account for more than 40% of the total failures of aero-engines.Therefore,it is necessary to apply damping vibration reduction technology to aero-engine blades.Air film damping technology has broad application prospects in aero-engine fan blade vibration suppression due to its simple structure,wide application range,and good vibration suppression performance.This paper first derives the air film damping force according to the squeeze film control equation,and the air film damping force is introduced into the plate structure vibration equation to derive the fluid-solid coupling control equation of the plate with air film damping;on this basis,further deduction the energy dissipation equation and damping ratio equation of the air film in each vibration period are discussed.Secondly,the Ansys Workbench finite element software was used to establish a fluid-solid-thermal multi-physics coupling simulation model with a air film damping plate,and the influence of the air film damping structure parameters on the vibration suppression performance under external excitation was studied.The experimental study on the vibration of the air film damping plate verifies the established simulation model.Finally,a fluid-solid-thermal multi-physics coupling simulation model of a fan blade with air film damping is established,and the influence of the air film damping structure parameters on the vibration suppression performance of the blade under external excitation is studied,and the influence of environmental temperature and pressure is further analyzed.The main conclusions of this paper are as follows:(1)The addition of air film damping structure has little effect on the inherent characteristics of the original plate and the fan blade.Both the simulation results and the experimental results show that the gas film damping can suppress the multi-order bending vibration of the flat plate.(2)The simulation results of the flat plate with air film damping and the fan blade with air film damping show that the vibration suppression performance of the film damping is related to the structural parameters of the air film.The best position of the air film is at the maximum amplitude;the length of the air film has an optimal value;the thickness of the vibration absorbing sheet also has an optimal value,which will slightly change near different natural frequencies;The reduction of the air film thickness is beneficial to improve its vibration suppression performance.(3)The air film damping structure is installed on the fan blades,which can suppress bending vibration,torsional vibration,and combined bending and torsion vibration.(4)The increase of ambient temperature and pressure will improve the vibration suppression performance of the air film damping. |
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