Research On Numerical Simulation Of Parachute Fluid-Structure Interaction

As an important tool for life-saving and decelerating system of aerospace mission,the structural deformation of parachute is usually large and transient,the evolution of surrounding flow is also complex and highly variable,which raise many difficulties and always attract the attention of parachute designers.Based on the key factors during this kind of simulations,a new parachute fluid-structure interaction method is proposed and developed based on the combination of preconditioning finite volume method?nonlinear finite element method and pseudo solid dynamic mesh algorithm.A preconditioning fluid dynamic solver is developed to simulate viscous flow problem at all speed.The spatial discretization is conducted by applying unstructured finite volume scheme.The time discretization methods used in pseudo time level is LU-SGS implicit iteration method,while the second order backward Euler difference method is applied in physical time iteration level.The flux accumulating algorithms including Roe and HLLC sheme have been applied to compute convective fluxes.The one equation Spalart-Allmaras turbulence model is employed to simulate viscous flow problem.The flux computation scheme as well as the LU-SGS iteration scheme have been modified and tested by the preconditioning algorithm to formulate a robust CFD solver to simulate parachute aerodynamic problems at all speeds.A membrane-cable nonlinear dynamic simulation code is developed by studying the nonlinear finite element theory.The wrinkling detection and simulation method are applied to modify the stress-strain results and eliminate the compressive stress within wrinkled area of fabric structure.In order to simulate the dynamic contact problems during parachute unfolding and inflation procedure,a contact searching algorithm with high efficiency is designed and the nonlinear contact governing equation based on penalty method has been established to predict the fabric contact problems.The large deformation tests are carried out to verify the accuracy of membrane-cable nonlinear finite element method.The single folded parachute inflation as well as the cluster folded parachute inflation have been simulated to verify the ability of nonlinear contact algorithm.Based on the large and arbitrary motion of parachute dynamics,a robust pseudo solid mesh deformation solver is developed to update the fluid mesh after structural deformation during fluid-structure interaction.Parallel computation techniques have been developed for those three independent module of parachute fluid-structure interaction method.Parallel efficiency have been tested individuality and the three numerical operation module have been finally assembled to formulate parchute fluid-structure interaction code.Two independent fluid-structure interaction simulation have been carried out for C-9 parachute and ATPS parachute respectively,the deformation results and vibration force results have been compared with former literatures which use different methods,thus demonstrates the ability of this new FSI code in predicting parachute configurations and calculating nonlinear dynamic forces of parachute system.