Experimental Study on Coupled Motions of Mother Ship Launching and Recovering of Human-Occupied Vehicle in Regular Waves

Abstract

The launching and recovery process of a human-occupied vehicle (HOV) faces more complex wave effects than other types of submersible operations. However, due to the nonlinearity between the HOVand its mother ship, difficulties occur in theoretically simulating their coupled motion and hydrodynamics. The coupled motion responses and the load under different regular wave conditions are investigated experimentally in this study. The optimized design of the experimental scheme simulated the launching and recovery process of the mother ship and HOV in regular waves. The attitude sensor performed synchronous real-time measurement of the coupled motion between the mother ship and HOV as well as obtained the load data on the coupled motion under different cable lengths. The results show that models in heading waves mainly lead to the vertical motion of the hoisting point. In beam waves, the transverse and vertical motions of the hoisting point occur in a certain frequency of waves. Under the heading and beam wave conditions, the longer the hoisting cable is, the greater the movement amplitude of the submersible is. Moreover, compared with the condition of the beam waves, the hoisting submersible has less influence on the mother ship under the condition of the heading waves. The findings provide theoretical support for the design optimization of the launching and recovery operation.

Preliminary Modeling of Coupled Motion Response for Floating Crane and Suspended Module by Using Boundary Element Approach and Empirical Model

“…In addition to being affected by the damping coefficient, the dynamic responses of floating cranes on the multibody system are significantly induced by the dynamic response of a swinging pendulum. According to the experimental study 8,12) , the oscillation of swinging suspended objects influenced the obstructed roll motion in beam seas.…”

“…In the results of transfer functions, there is a frequency resonance in the rolling motion due to the oscillation of the suspended module. Chen et al 12) explained that the length of cable on the suspended human-occupied vehicle (HOV) has a clear influence on the mother ship's response in the launching process, which is calculated using an experimental method.…”