The parachute inflation process is a typical time-varying, non-linear and fluid-structure coupling problem, especially inairdrop condition. For its complexity, numerical model of the inflation process is a big challenge, and most of the modelsestablished before still have room for improvement. There were two common problems that the first one was ignoranceof inertia force of canopy and line, and the second was that took stretch speed as the initial airdrop speed in modelling.Thus, a modified finite element model for canopy inflation process based on ALE (Arbitrary Lagrange Euler) method wasestablished that the inertia force of canopy and line was taken into consideration and the initial airdrop speed wasestimated and adjusted. The opening load in finite mass situation during deployment-inflation process of C-9 typeparachute was calculated. The result was compared to experimental data and calculated data of unmodified models. Itwas indicated that the opening load and peak time of modified model was the closest to experiment and the snatch loadwas also calculated and confirmed, so that the correctness and rationality of the model was verified. Then the factorinfluence of inertia force and initial airdrop speed was analysed, which provided a reference for parachute numericalmodelling.
In this approach, the numerical model of the fluid dynamics of liquid droplets impacting on the fabric surface with VOF method is proposed. The results obtained by the proposed model are well in agreement with the experimental results. The mechanism of the liquid droplet morphological evolution is investigated by pressure distribution and velocity vector, and the obvious bubble entrapment, which cannot be observed in experimenal results, is captured by the proposed model. The evolution laws of the spreading factor and the contact angle at the liquid-porous interface are obtained and the reason why the contact angle is dynamic is analyzed. The effects of droplet diameter and impact velocity on the fluid flow characteristics are also discussed. Usually, droplet diameter increasing leads more dramatic shape distortion of the liquid droplet, and impact velocity increasing leads shorter time to reach the maximum spreading stage. Finally, based on the properties of the impacting droplet by the proposed model, the important references of optimizing the parachute design for severe weather are built.
The parachute inflation process is a typical time-varying, non-linear and fluid-structure coupling problem, especially inairdrop condition. For its complexity, numerical model of the inflation process is a big challenge, and most of the modelsestablished before still have room for improvement. There were two common problems that the first one was ignoranceof inertia force of canopy and line, and the second was that took stretch speed as the initial airdrop speed in modelling.Thus, a modified finite element model for canopy inflation process based on ALE (Arbitrary Lagrange Euler) method wasestablished that the inertia force of canopy and line was taken into consideration and the initial airdrop speed wasestimated and adjusted. The opening load in finite mass situation during deployment-inflation process of C-9 typeparachute was calculated. The result was compared to experimental data and calculated data of unmodified models. Itwas indicated that the opening load and peak time of modified model was the closest to experiment and the snatch loadwas also calculated and confirmed, so that the correctness and rationality of the model was verified. Then the factorinfluence of inertia force and initial airdrop speed was analysed, which provided a reference for parachute numericalmodelling.
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