Numerical Analysis Of Aircraft Ditching Based On SPH Method

With the thriving of aviation industry, over-sea flight missions of aircraft become more and more frequent. Therefore, the probability of emergency ditching accident also increases significantly. According to "China’s Civil Aviation Regulation department:25 transport category aircraft airworthiness standards", which promulgated by the Civil Aviation Administration of China, it requires aircraft must has good ditching performance to obtain a certificate of airworthiness. Compared to the expensive and time-consuming experimental methods, numerical simulation as one of the alternative methods to investigate the aircraft ditching performance is widely valued by researchers all over the world.In this thesis, the Smoothed Particle Hydrodynamics (SPH), which has advantages over simulating high deformation of materials, fluid and structure interaction and liquid splashing, is used to simulate aircraft ditching. First, through three confirmatory simulation, the reasonableness and correctness of using SPH to simulate ditching are validated. Some important attribute data and keywords paragraph are also verified in the meantime. Second, ditching models are constructed. In this phase, the influences of wing lift and tail suction on ditching simulation are discussed. Different simulations are carried out according to different working conditions, and analyses of the velocity, attitude angle and vertical displacement of the center of gravity during each condition are conducted. Finally, sea wave model is built. Two specified ditching simulation are completed and the kinematics of aircraft in those conditions are discussed. Through the two specified wavy water ditching simulation, some conclusions are provided and they also serve as a foundation for the subsequent processing. According to the overall simulation results, it can be found that:1. The SPH method is suitable for simulating aircraft ditching; 2. During ditching simulation, the tail suction plays an important role; 3. Waves generated by SPH method have realistic effects.4. Waves have negative effects on ditching simulation and it should be avoided to make an emergency landing on severe sea conditions.