The Influence Of Ship Motion On The Take-off And Landing Process Of Aircraft

Ski-jump take-off is one of the important means of aircraft take-off,because of the limited size of ship,and it’s six degrees of freedom movement when sailing in the sea,taking off on ship is more complex than taking off on land,the security of ski-jump take-off has attracted increasing attention.In addition,due to the high speeds of ship and the motion of the deck,there exists complex flow disturbance,the ship airwake changes with different ship motion,serious airwake will even make the aircraft unable to land safely.In this paper,the aircraft take-off and landing process under different conditions of ship motion were studied,which provides technical support for the safe of aircraft take-off and landing.Firstly,the simplified frigate ship SFS1 was numerically simulated,and the results were compared with the experimental data,the feasibility of the calculation method was verified.Secondly,considering the different conditions of the ship motion(rolling and pitching motion),lattice Boltzmann method and WALE turbulent model were used to simulate the take-off process of the aircraft at the wind speed of 25m/s.The simulation results of deck flow field and ship airwake were compared under different conditions,the influence of deck motion on aircraft takeoff and landing was analyzed.Overall,the aircraft is greatly affected by the vortices in skid deck during takeoff,including the vortices generated by the flow around the bow and the vortices at the edge of the deck.Downwash flow exists in the middle of the skid deck,and upwash flow appears near the bow.When the roll motion occurs,the distribution of vortices on both sides of the deck is quite different,especially near the bow,the vortices will increase on the side of the rising deck,the vortices will decrease on the other side,this asymmetric distribution will affect the takeoff.When there is a pitch motion,boundary layer separation occurs near the bow,the flow field becomes more complex.The velocity distribution of downwash flow and upwash flow on the skid deck is greatly affected by the pitching motion,and the velocity of upwash flow increases with the increase of the upward pitching angle.The maximum velocity can reach to 10.5m/s,that’s conducive to the aircraft take-off.In addition,when the aircraft enters the skid deck,the lateral force is proportional to the speed of the aircraft and the angel of rolling motion,the maximum force is over 10 KN,the safety of takeoff is seriously affected.The variation of horizontal force and vertical force is large when the pitching motion occurs.This phenomenon changes with the speed of the aircraft and the pitch angle.At the time of landing,the aircraft can safely fly over the height of 41 m above the deck.As the flight altitude decreases,the aircraft will be affected by upwash flow and downwash flow.When the ship is moving,the lateral velocity component of ship airwake within the height of 21 m above the deck has a certain fluctuation.The pitching motion has a great influence on the vertical velocity component,the maximum velocity of downwash flow can reach to 10m/s,which is a great threat to the landing safety of the aircraft.