基于降落伞的重要应用与设计的实际需要,降落伞的数值模拟开始得到越来越多的重视,而充气过程是其中最为复杂的一个阶段。本文建立了平面圆形伞主充气过程中的CFD(Computational Fluid Dynamics)与结构动力学的MSD(Mass Spring Damper)...基于降落伞的重要应用与设计的实际需要,降落伞的数值模拟开始得到越来越多的重视,而充气过程是其中最为复杂的一个阶段。本文建立了平面圆形伞主充气过程中的CFD(Computational Fluid Dynamics)与结构动力学的MSD(Mass Spring Damper)之间的耦合模型。流场求解采用稳定性较高的标准k-ε模型,在多块贴体坐标下,获得某时间节点处的流场,并将该流场中的压力数据引入MSD模型,以获得下一时间节点的伞衣形状,最终获得主充气过程中伞衣形状和流场之间的动态关系。数值计算结果和实验结果及经验值比较,均有较好的一致性。充气过程的数值求解有助于提高对降落伞充气过程机理的理解。展开更多
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 struct...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 infla- tion process of a folded parachute, and the flow field calculation is mainly based on operator split- ting 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 cap- tured. 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 optimi- zation during parachute design.展开更多
The fluid-structure interaction (FSI) between the canopy and flow field on the inflating and inflated conditions is investigated based on the arbitrary Lagrange-Euler (ALE) method,in both a single-and double-cruciform...The fluid-structure interaction (FSI) between the canopy and flow field on the inflating and inflated conditions is investigated based on the arbitrary Lagrange-Euler (ALE) method,in both a single-and double-cruciform parachute systems.The projection area of canopy is calculated in the inflation process.The flow field characteristics and the interaction between canopies are analyzed.Results showed that,with free stream velocity of 50m/s,overinflation phenomenon would not occur during the inflation process of the double-cruciform-parachute system,because the collision and extrusion of the two canopies during inflation obstructed the oscillation of the inner gores.Concurrently,compared with the single-cruciform parachute,the vortex motion in the wake of double-cruciform-parachute is more intense.Thus the double-cruciform parachute system oscillated at a velocity of 50 m/s with an angle of less than 6.8°.By comparison,the oscillation angle of the single-cruciform parachute was within 3.5° at the velocity of 50m/s.The results are consistent with those of the wind tunnel test.展开更多
文摘基于降落伞的重要应用与设计的实际需要,降落伞的数值模拟开始得到越来越多的重视,而充气过程是其中最为复杂的一个阶段。本文建立了平面圆形伞主充气过程中的CFD(Computational Fluid Dynamics)与结构动力学的MSD(Mass Spring Damper)之间的耦合模型。流场求解采用稳定性较高的标准k-ε模型,在多块贴体坐标下,获得某时间节点处的流场,并将该流场中的压力数据引入MSD模型,以获得下一时间节点的伞衣形状,最终获得主充气过程中伞衣形状和流场之间的动态关系。数值计算结果和实验结果及经验值比较,均有较好的一致性。充气过程的数值求解有助于提高对降落伞充气过程机理的理解。
基金co-supported by the National Natural Science Foundation of China (No. 11172137)the Aeronautical Science Foundation of China (No. 20122910001)
文摘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 infla- tion process of a folded parachute, and the flow field calculation is mainly based on operator split- ting 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 cap- tured. 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 optimi- zation during parachute design.
基金supported in part by the Aeronautical Science Foundation of China(No.20172952031)the Aeronautical Science Foundation of China (No.20142952026)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘The fluid-structure interaction (FSI) between the canopy and flow field on the inflating and inflated conditions is investigated based on the arbitrary Lagrange-Euler (ALE) method,in both a single-and double-cruciform parachute systems.The projection area of canopy is calculated in the inflation process.The flow field characteristics and the interaction between canopies are analyzed.Results showed that,with free stream velocity of 50m/s,overinflation phenomenon would not occur during the inflation process of the double-cruciform-parachute system,because the collision and extrusion of the two canopies during inflation obstructed the oscillation of the inner gores.Concurrently,compared with the single-cruciform parachute,the vortex motion in the wake of double-cruciform-parachute is more intense.Thus the double-cruciform parachute system oscillated at a velocity of 50 m/s with an angle of less than 6.8°.By comparison,the oscillation angle of the single-cruciform parachute was within 3.5° at the velocity of 50m/s.The results are consistent with those of the wind tunnel test.
