Study On Damping Performance Of Landing Gear Shock Absorber Throttle Device

The sinking speed of the aircraft in various landing conditions is from 3m/s to over 10m/s,the shock absorber absorbs most of the impact loads that the aircraft suffered during landing.While absorbing and dissipating energy,the buffer overload of the landing gear must be limited within the set range.Therefore,the shock absorber is one of the most critical components to ensure the safety of the aircraft landing.Oleo-pneumatic shock absorbers are employed in most modern aircraft landing gear,the damping performance of the shock absorber throttle device is the key factor that influence the energy dissipation and overload restriction.For the conceptual design of the shock absorber,the estimation formula for the oil damping characteristics is rough and covers a wide range in the existing design manual.The theoretical calculation method of damping characteristic based on the orifice characteristics and parameters is still lacking in the characteristic conceptual design of the shock absorber typical damping valve.In addition,due to the complex structure and flow field of the valve body,the design theory and method of variable damping throttle device are still lacking.In this paper,based on the knowledge of pipeline hydrodynamics,the theoretical analysis of the shock absorber throttle devices is performed.Finite element analysis is also conducted for the throttle device structures using the commercial computational fluid dynamics(CFD)software FLUNET.By this method,the influences of orifice parameters such as length diameter ratio,aspect ratio and orifice chamfering on the damping performances of the fixed orifice are analyzed.On this basis,a sectional modeling and analysis method for an inner spring throttle valve is proposed and the damping characteristic analysis is carried out.Finally,the certain type landing gears drop dynamic performances are calculated using obtained damping performances and compared with experimental results.The data demonstrates that the damping performances can be calculated accurately by the CFD simulation method,whether it is a variable damping or a fixed orifice throttle device.The above research provides a more precise and efficient design method for the throttle device in the conceptual design stage of landing gear shock absorber,which enriches and develops the design technology of landing gear shock absorber throttle device.