翼伞充气过程的流固耦合方法数值仿真

为研究冲压式翼伞折叠充气过程的流固耦合动力学特性，基于自由曲面变形理论建立了多气室冲压翼伞的展向折叠模型。流体域通过时步更新技术实现了随伞载系统运动，采用任意拉格朗日-欧拉（ALE）方法开展了翼伞非定常充气展开过程的非线性动力学数值计算，数值计算结果与空投试验结果具有较好的一致性。深入分析了翼伞充气过程中的三维外形及非定常流场分布情况，表明翼伞充气过程由于翼尖涡绕流，存在“翼尖上翘，中部凹陷”的翼伞尾流再附现象；各气室的充气规律关于中央气室对称；分析了翼伞气动特性的动态变化规律，充满后翼伞滑翔比稳定在2.24。上述研究为翼伞设计及开伞性能预测提供了一定的理论依据。 

Numerical simulation of parafoil inflation process based on fluid-structure interaction method

To study the fluid-structure interaction dynamic characteristics of rammed parafoil during inflating process, a folding model of rammed parafoil with multi-chamber was established based on the theory of free form deformation. The time-step updating technique was used to make fluid field move with the movement of the parafoil system. The nonlinear dynamics numerical calculation was carried out with Arbitrary Lagrange-Euler (ALE) method during the unsteady parafoil inflation process. The numerical results are in good agreement with the airdrop test results. The three-dimensional shape and unsteady flow field distribution indicate that there exists a wake recontact phenomenon with "tip warping and central depression" due to the tip vortex during parafoil inflation process. The inflatable law of each chamber is symmetrical with respect to the central chamber. The dynamic variation law of parafoil aerodynamic characteristics is analyzed and the glide ratio is stable at 2.24 after inflation. The conclusions provide a theoretical basis for parafoil design and inflation performance prediction.