Numerical Study of Extra-Large Parachute’s Pre-Inflation in Finite Mass Situation

Abstract

The extra-large parachutes were different from the common parachutes because of their size and opening process. Some undesirable inflation phenomena such as canopy winding and whipping usually appeared in their pre-inflation process. However, the mechanical mechanism of these phenomena was very difficult to be explained by experimental means. In this paper, the pre-inflation process in finite mass situation of an extra-large parachute was calculated by explicit finite elements. According to the results, the pre-inflation process can be subdivided into symmetric inflation stage, undesirable inflation stage, and stable inflation stage. The canopy winding and whipping mainly occurred in the second stage. With the continuous deceleration of parachute-payload system, the top of canopy without effective constraints would appear winding and whipping under the function of inertia force. The canopy winding and whipping increased the difficulty of canopy expanding and then caused asymmetric inflation. The above undesirable phenomena had a great influence on the deceleration effect and were easy to cause the recovery failure. The actual airdrop experiments also proved that the lack of effective constraints on the canopy top will cause undesirable inflation phenomena. The conclusions in this paper can also provide a reference for extra-large parachute design and research.

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“…Gao established a slotted parachute model by ALE method [2] and the adaptive mesh technology in airdrop situation, calculated the drag coefficients and analysed the influence of initial airdrop speed. Cheng calculated the opening process in a finite mass situation [3][4][5], and analysed the interrelation between dangerous section, overload and canopy shape.…”