Research On Aeroplane Ditching Numerical Simulation Based On SPH Method

At present, trade are getting closer between nations, over-sea flies become more and morefrequent. Thus airplanes have to get an excellent ditching performance. As a requirement ofAirworthiness Regulation, there are two ways to study the ditching performance: test and numericalsimulation. Nevertheless the recommends of huge cost and time resuming to test, numericalsimulation have plenty of advantages.A SPH method, namely Smoothed Particle Hydrodynamics method, to study airplane ditching ispresented in this project. Contrast to other FEMs which cannot simulate the large deformation,fluid-structure coupling and liquid splash, SPH method has its unique creativity to solve the freesurface problem.Firstly, this paper introduces the SPH method theory, and gives the Kernel approximation andParticle approximation function. Then the author presents the equations of Conservation of mass,Conservation of momentum and Conservation of energy for fluid dynamics and structure dynamics.Secondly, with reference of wedge impacting water test from a published paper, this projectbuilds a model to simulate this test. With a comparative study on process picture and wedgedisplacement of test and simulation, SPH method has the ability to simulate phenomena of watersplash and breaking, and the simulation results are very consistent with test phenomena.Thirdly, the author builds airplane model and wave model. Based on the state of landing gear andattitude angle, this project designs seven simulation conditions, and analyzes velocity, accelerationand attitude angle during ditching of each condition. In consideration of the minimal drag force andattitude angle variation, a conclusion of the optimum ditching attitude is present.The major work of this project is the application of the advantage of SPH method to simulateimpacting problem to simulate airplane ditching, then provides a valuable reference to later airplanedesign work.