Simulation of Falling-floating Process of Vehicle with Ellipsoidal Airbags
A recovery scheme of vehicle with ellipsoidal airbags is proposed for the problem of model falling into the water at low speed in the underwater launch model test.The numerical simulation is based on Abaqus coupled Eulerian-Lagrangian method,and the effectiveness of the numerical method is verified by comparing the numerical and experimental results of the AUV head section entering into the water.The motion process of the vehicle with airbags entering the water at low speed,the change of airbag pressure and the force of the connecting belt under the conditions of different attitude angles and different initial airbag pressures are analyzed.The results show that the attitude angle of vehicle is the most important factor affecting the falling-floating process,followed by the initial airbag pressure.For the maximum depth of falling into the water,the peak value of airbag pressure and the peak value of pulling force,the condition that tends to fall vertically is more dangerous,the maximum depth of falling into the water is 1.33 times the length of vehicle,the maximum airbag pressure is 3.7 times the baseline airbag pressure,and the maximum pulling force of connecting belt is 2.2 times the gravity of vehicle.These conclusions can provide a reference for the design of recovery scheme and structural parameters for the vehicles falling into the water.