Analysis of Multi-Body Separation Characteristics of Trans-Medium Vehicles

Abstract

This paper studied the underwater separation characteristics of pods of trans-medium vehicles by numerical simulations of computational fluid dynamics and dynamics model simulations and analyzed the hydrodynamic forces exerted on the pods before and after separation. The analysis results show that 1) with appropriate shapes, the pods can separate from the vehicle under the action of hydrodynamic forces; 2) the opening angle and opening angular velocity of the pods have a large impact on the hydrodynamic forces. At different opening angles, the generation mechanisms of the separation moment are different. At a small opening angle, the opening of the pods mainly relies on the internal and external pressure difference generated by the low pressure in the outer separation zone, and the fluid moment is mainly generated by the front section of the pods. At a large opening angle, the opening of the pods mainly relies on the normal force caused by water flow impact, and the moment is mainly generated by the middle and rear sections of the pods; 3) the damping moment of the fluid is large when the opening angle of the pods is small, which makes it hard for the pods to separate from the vehicle quickly at the initial stage. As the opening angle increases, the damping moment of the fluid gradually decreases, and the opening angular velocity of the pods rapidly increases. Therefore, appropriate shapes and separation methods should be designed to reduce the initial damping moment of the fluid of the pods during underwater separation.

Keywords

• trans-medium vehicle
• underwater separation
• multi-body separation
• pod