A direct numerical modeling method for parachute is proposed firstly, and a model for the star-shaped folded parachute with detailed structures is established. The simplified arbitrary Lagrangian–Eulerian fluid–structure interaction(SALE/FSI) method is used to simulate the inflation process of a folded parachute, and the flow field calculation is mainly based on operator splitting technique. By using this method, the dynamic variations of related parameters such as flow field and structure are obtained, and the load jump appearing at the end of initial inflation stage is captured. Numerical results including opening load, drag characteristics, swinging angle, etc. are well consistent with wind tunnel tests. In addition, this coupled method can get more space–time detailed information such as geometry shape, structure, motion, and flow field. Compared with previous inflation time method, this method is a completely theoretical analysis approach without relying on empirical coefficients, which can provide a reference for material selection, performance optimization during parachute design.
The damping-controlled deployment technology of flexible Z-folded inflatable tube is one of the key technologies of space inflatable structures.Constraint failure between couple nodes is proposed to simulate the damping-controlled deployment.And the equation of constraint failure is established.Inflation process of Z-folded tube is simulated with control volume method.Compared with uncontrolled method,it is indicated that the new method can effectively solve the disordered deployment problem of the slender Z-folded inflatable tube.By analyzing the displacement of the apical of the folded tube with different constraint forces during deployment process,the concept of effective constraint force is proposed.In the effective region of constraint force,the folded tube deploys with little retraction and fluctuation.Otherwise,The flexible folded tube would deploy disorderly or even cannot deploy.The simulation method and numerical results have a theoretical and instructive significance to the research on the space inflatable structures.
The inflation of a five-ring cone parachute with the airflow velocity of 18m/s is studied based on the simplified arbitrary Lagrange Euler(SALE)/fluid-structure interaction(FSI) method.The numerical results of the canopy shape,stability,opening load,and drag area are obtained,and they are well consistent with the experimental data gained from wind tunnel tests.The method is then used to simulate the opening process under different velocities.It is found that the first load shock affected by the velocity often occurs at the end of the initial inflation stage.For the first time,the phenomena that the inflation distance proportion coefficient increases and the dynamic load coefficient decreases,respectively,with the increase in the velocity are revealed.The above proposed method is competent to solve the large deformation problem without empirical coefficients,and can collect more space-time details of fluid-structure-motion information when it is compared with the traditional method.
