The water entry problem of a wedge is simulated based on the velocity potential theory in time domain. The Complex Variable Boundary Element Method (CVBEM) is used in the stretched coordinate system. Before the simulation, the similarity solution is taken as the initial conditions. The auxiliary function scheme in conjunction with the same CVBEM is used to obtain the accurate time derivative of velocity potential and pressure distribution on wedge surface. The time marching solution is matched with the jet special treatment. Finally, the simulation results are compared with the similarity solution, which shows that the jet linear approximation can simulate the jet well.
Aircraft Ditching is related primarily with the aviation safety. Firstly, the full-scaled shape of Boeing 777-200 is modeled according to the lost MH370 aircraft on 8th March. And then an Arbitrary Lagrange-Euler (ALE) fluid-field model is created for water and air domain. Next some simulation cases are implemented related to different vertical velocities using LS-DYNA nonlinear finite-element code, with the same horizontal velocity and attack angle. At the same time, the variations of the velocity of the head and tail are discussed. Consequently, Ditching overload peak occurs at the highest vertical velocity. The simulation results can deeply be applied to accident analysis of aircraft impacting on water.
In order to meet the requirements of increasing domestic airline pilot training and flight safety, airline pilot training departments pay special attention to flying qualities of advanced teaching aircraft. According to the application of equivalent systems in aircraft flying quality evaluation system, the selection method of initial value and equivalent system and the evaluation index of equivalent systems are analyzed. A modeling and simulation example is given to an advanced teaching aircraft, and it increasingly demonstrates that the adoptive equivalent system method applied to flying quality evaluation of advanced teaching aircraft is feasible.
It is significant for the phenomena of bouncing on water to analyze the ditching procedure of any kind of aircraft. The SPH method is employed to achieve a numerical simulation in the architecture of LS-DYNA and PrePost programs. The water domain is modeled by SPH and the boundary condition is discussed too. Through a set of contrastive analysis of different boundary conditions, some constructive suggestions of establishing the boundary conditions are given to deeply simulate aircraft ditching in the future.
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