Propellant Flow Characteristics in Tank and Related Impact Analysis During the Vertical Landing Stage

Reusable technology is one of the key factors to realize the launch vehicle reusability. It is a hot spot in current research to achieve the sub-stage reusability by vertical landing. During the process of launch vehicle taking-off and vertical landing, the propulsion system is not only required to provide thrust in the ascent, but also to realize the smooth deceleration and control of vertical landing. It is required that the rocket engine shall be improved to possess multiple-start and in-depth thrust regulating capability and also have higher requirements to propellant management. During the vertical landing process, the propellant flow characteristics in tank are greatly affected by the acceleration of the vehicle. If there are some lateral disturbance, the propellant in the tank will move violently due to severe acceleration decrease and may affect the normal operation of the rocket engine. In this paper, the propellant flow behavior during the vertical landing process is investigated with Flow 3D numerical simulation, and the influence of the lateral and axial acceleration on the propellant flow behavior during the engine shutdown process is analyzed. The results show that the sloshing amplitude of the propellant is related to the amplitude of the lateral disturbance when the axial acceleration changes to a certain extent, and the sloshing amplitude of the propellant will be greatly enlarged when axial forces suddenly decrease. It is suggested that in the process of vertical taking-off and landing, the attitude of vehicle should be guaranteed as much as possible to avoid large lateral disturbance.