Numerical Simulation Of Aircraft Carrier Airwake And Preliminary Study On Control Law For Automatic Carrier Landing

The carrier-based aircraft approach and landing is the key technology of modem carrier/carrier-based aircraft system. Which cover multi-subject like flight dynamics, aerodynamics, ship hydrodynamics, control and navigation. The airwake can significantly affect carried-aircraft’s glide path and reduce the safety during recovery to the flight deck. How to improve the performances of airplane in landing through airwake region is very important.First, Computational fluid dynamics is used to create an aerodynamic ship airwake database, and the influence of wind over deck and ship moving state on airwake is emphasized. The research show that the higher the wind speed is, the stronger the airflow disturbance to the airplane. Along with the wind direction changed, the airwake region of influence changed obviously, it could be concluded that airwake region is mainly affected by wind direction. Results show that the periodic component of airwake is caused by ship’s pitch and heave motion, the nearer the ship, the stronger the periodic component of airwake.Second, equations of longitudinal aircraft nonlinear motion is created for aircraft flight through the airwake region, the flow field analog data from CFD can serve as input to the dynamics model by looking up table interpolation. The flight parameters are acquired when the aircraft approach and landing in airwake through simulation. Results show that the aircraft encounter the tailwind, upwash and tailwind, downwash distributions in turn during the approach process, the aircraft drift upward first and then sink quickly near aft due to lift reduce, As a result, the actual landing point on the carrier deck deviate the designated touchdown point.Lastly, nonlinear dynamic inversion and PID algorithm are used to solve the difficulty problem of automatic landing of carrier-based aircraft. Singular perturbation theory is applied to divided the whole system into three simple subsystems, each loop’s controllers are designed from the inside to the outside respectively. The simulation results prove that the control law not possesses a good decoupling capability and trajectory tracking performance, but also is robust to airwake disturbances. How to enhance the robustness ofthe control system is still the key areas of our future work.