INVESTIGATION OF DYNAMIC CHARACTERISTICS ABOUT VEHICLE WITH AIRBAGS STRUCTURE DURING WATER-ENTRY AND RECOVERY

Aiming at the problem in the recovery of large-scale model vehicle that the excessive depth during the water-entry process may affect the safety of the launch platform, the vehicle with airbag structure is designed in this paper to improve the recovery efficiency of the whole process, which is considered to be released from the air before water-entry and float synchronously with the vehicle to ensure the recovery of the structure. And the specific design parameters of the model are also shown in this paper. At the same time, the numerical calculation model of the airbag structure during water-entry and recovery process is established based on the CEL algorithm. Combined with the experimental results of the sphere and the AUV head section during water-entry, the validity of the numerical method was verified and the irrelevant mesh scale was also selected. On this basis, the calculation of vehicle recovery during vertical water entry with different airbag volumes was carried out to select the optimum volume. Subsequently, a series comparative analysis of the recovery process over the structure was carried out for different water-entry parameters (the entry velocity, angle of attack and the fixed position of the airbags). The results show that the volume of the airbag has a positive correlation with the recovery efficiency, and that the volume should be selected taking into account the recovery efficiency and the pressure response. The increase in water-entry velocity causes a simultaneous increase in the magnitude of system motion, which is detrimental to recovery. The different angles of attack or airbag fixed position during the water-entry cause the difference in the deflection motion (attitude evolution) between different stages of the vehicle recovery process, and the water-entry with larger angle of attack and fixed position at the middle is beneficial to the recovery of the model.