Numerical investigation of ram-air parachutes inflation with fluid-structure interaction method in wind environments

A novel nonlinear numerical model for folded ram-air parachutes inflation in wind environments is proposed based on graphical deformation and arbitrary Lagrange-Euler method. The Constrained Free-Form Deformation algorithm is introduced to implement the spanwise modeling of folded ram-air parachutes. The finite mass inflation simulation adopts Time-step Motion Method. The convection of flow field is set up by initial and boundary conditions to introduce the wind speed. This method is used to study the fluid-structure interaction dynamic characteristics of the folded ram-air parachutes inflation process in wind environments, and the transient 3D canopy shapes, surrounding flow field and opening load are obtained. The results show that the numerical result of opening load is consistent with the airdrop test. There exists a wake recontact phenomenon at the initial inflation stage. Besides, wind environments affect the inflation performance. Under upwind, the parachute inflates well and keeps a certain elevation angle. However, in the downwind or crosswind state, the payload-parachute system is unstable and unable to work. The maximum opening load in wind environments is larger than that without wind. And the stress concentration occurs at the leading edge and the stability fins. This manuscript can provide a reference for ram-air parachutes design and inflation performance optimization.