Research on the characteristics of cavitation flow and pressure load during vertical water exit of different head-shaped vehicles

It is a complex process for a vehicle to emerge from the water. During this period, the cavitation flow state and the load on the vehicle change sharply, which has a great impact on the movement of the vehicle. It is necessary to study the cavitation flow state and loading characteristics during the process of water-exit. At present, the research on this aspect at home and abroad mostly focuses on the use of commercial software or self-written programs to simulate the pressure distribution on the surface of the extended vehicle and the flow field at the head of the vehicle during the process of water exit. However, there is a lack of relevant experimental data on the changes of pressure and cavitation flow regimes during the water-exit process of different head-shaped vehicles. The research on water plumes mostly focuses on the interaction between the explosion bubble and the free surface, but there is little research on the water plumes generated when different head-shaped vehicles exit the water. Based on this, this paper designs a set of surface pressure load measurement system for the water-exit process of the vehicle under the decompression environment, and designs and processes the vehicle with different head types such as cone head, hemispheric head, and swelling conical head. The flow characteristics and pressure loads of different head-shaped vehicles in the initial stage, development stage and collapse stage of cavitation were studied. The study found that the shape of the vacuoles in the initial stage, the development stage and the collapse stage of different head-shaped vehicles is quite different, and the change process of the pressure is also different; In addition, the water plumes generated when the vehicle is out of water can be divided into three categories according to the collapse method, and the collapse time of each type are also different. •The cavitation flow characteristics and pressure changes of different head-shaped vehicles in the process of underwater vertical motion were explored by experimental methods•Three different types of water mounds are proposed when the vehicle emerges from the water, and are explored by means of experiments.•Using the pressure sensor to record the pressure changes of the vehicle during the underwater movement phase and the water exit phase.•The contour of the cavitation bubble is more accurately extracted by using the boundary recognition program