Fluid-Structure Interaction Study on the Influence of Circular Gap of Parachute on Inflation Performance with Fixed Payload
Journal of Engineered Fibers and Fabrics
In order to study the influence of circular gap controlled by the tearing force on rescue parachute inflation performance, the Arbitrary Lagrange-Euler (ALE) coupling method is utilized to simulate the inflation process of the circular gap rescue parachute with fixed payload; the contact failure model of the open of circular gap was built by the sewing force of the sewing thread. The canopy structure model influenced by fabric permeability performance is proposed, and the differential pressure
... ferential pressure of permeable fabric is described in Ergun equation through the textile material permeability test. The numerical results calculated by LS-DYNA are compared with the results of airdrop test and the empirical method of parachute-payloads dynamics, and it is shown that the steady drag coefficient and transient shape during inflation are more consistent with the airdrop test results, and the dimensionless initial inflation time and the maximum equivalent opening shock are more realistic. The stress variations of each gore unity during inflation are investigated. The most dangerous time-space state point during inflation process was discovered. With the study of the influence of the circular gap structure of parachute on inflation performance, the numerical results show the circular gap structure can reduce the opening load and adjust the time of two inflation stages, which reduces the maximum effective stress in dangerous parts and improves the safety of canopy. INTRODUCTION Maximizing the work scope of a rescue parachute is a serious challenge for all designers: on the one hand the rescue parachute should provide rapid opening and inflation at low altitude and low speed to ensure enough open height and terminate descent time, on the other hand the rescue parachute should provide slow inflation and small open shock at high altitude and high speed to ensure the safety of pilot. To solve the above conflicts, the most effective method is to utilize an adjustable ventilation structure. A number of experiments show that multi-gap adaptive gore structure can decrease open load through increasing ventilation at high speed . Because of the improvement of the work scope of a rescue parachute, current adaptive gore design could not meet the requirement of higher opening velocity. The circular gap structure of a rescue parachute, which can be torn by opening force influenced by velocity, becomes an important measure to reduce the opening load at high speed and to quickly up the inflation at low speed. In order to effectively assess the influence of circular gap structure on inflation process and realize the goal of the optimization design of circular gap, the inflation process of this structure parachute is investigated by fluid-structure interaction (FSI) method.