基于多相态流体/织物耦合的风雨环境下伞衣充气过程研究

In order to study the mechanical mechanism of the wind and rain effect on parachute inflating process, a new multiphase fluid-structure coupling model is proposed in this project. The single raindrop is described by SPH particle cluster, and the air flow field and the parachute are described by Finite Elements (FE). In the numerical calculation, the SPH model will apply Leapfrog (LF) scheme in time marching, and the FE model will apply the central difference scheme. All of the materials in calculation are based on Lagrangian description. Therefore the coupling forces could be obtained by contact calculation based on penalty function. While in order to reduce the calculation amount, the adaptive motion of air flow field meshes and SPH/FE coupling calculation domain are proposed. The graphical deformation technology is refered to realize the adaptive motion. The transformation matrix is obtained by the change of a local coordinate on payload, and then new position of meshes and domain could be determined according to the matrix. In addition, the experiment of liquid drop impacting on fabric will be used to verify the accuracy and rationality of the rain model, and the parachute tower test will be used to verify the numerical results. By using the above method, the mechanical mechanism of wind and rain effect on parachute inflating could be revealed. The influence degree of wind and rain will be evaluated, and the corresponding optimization and prevention measures will be proposed. The research results could provide references for the parachute design which is used in atrocious weather or outer space. The results also could be refered by other inflatable fabrics design.

为研究外界风雨环境影响伞衣充气的力学机理，本项目提出全新的多相态流体/织物耦合模型：其中雨滴场采用SPH（Smoothed Particle Hydrodynamics）粒子团描述，而风场和伞衣采用有限元（Finite Element, FE）描述。在计算中SPH粒子采用蛙跳格式推进，而有限元模型则采用中心差分格式，由于所有材料都基于拉格朗日描述，因此，不同相态流体/织物间的耦合力可以通过罚函数接触算法获得。同时为了降低计算量，本项目借鉴图形变形法，通过局部坐标获得变换矩阵，实现空气流场和SPH/FE耦合计算域自适应运动。此外，本项目拟采用液滴/织物碰撞试验和伞塔试验验证雨滴模型和数值方法的准确性。通过上述方法揭示风雨环境影响开伞的力学机理，评估不同程度的风雨环境对开伞影响程度，并提出优化和预防措施。研究成果可以为后续极恶劣环境和外空间开伞或其他充气织物工作过程研究提供参考。

为研究外界风雨环境影响伞衣充气的力学机理，本项目开展单液滴撞击织物的数值和试验研究，同时本项目提出全新的多相态流体/织物耦合模型：其中雨滴场采用SPH（Smoothed Particle Hydrodynamics）粒子团描述，而风场和伞衣采用有限元（Finite Element, FE）描述。在计算中SPH粒子采用蛙跳格式推进，而有限元模型则采用中心差分格式，由于所有材料都基于拉格朗日描述，因此，不同相态流体/织物间的耦合力可以通过罚函数接触算法获得。同时为了降低计算量，本项目借鉴图形变形法，通过局部坐标获得变换矩阵，实现空气流场和SPH/FE耦合计算域自适应运动。此外，本项目采用空投试验验证雨滴模型和数值方法的准确性。通过上述方法揭示风雨环境影响开伞的力学机理，评估不同程度的风雨环境对开伞影响程度，并提出优化和预防措施。研究成果可以为后续极恶劣环境和外空间开伞或其他充气织物工作过程研究提供参考。