Tudy On The Stability Of Longitudinal Motion Of A Double-m-hull Ship Based On Channel Wing Wave Presses

With the rapid development of the marine industry,more and more boat models are appearing in people’s view,among which the Double M-hull ship,which combines the features of multi-hull boats,gliding boats and micro-bubble drag reduction boats,is particularly eye-catching.The double M-hull ship uses its unique structural characteristics to capture air during navigation,and with the help of static buoyancy,hydrodynamic force and aerodynamic force augmentation,it makes the hull water resistance greatly reduced,breaking the limit of the speed of conventional boat models.Its transverse structure similar to that of multihull boats makes the hull length and width relatively small and has good transverse stability.In recent years,with the development of CFD technology,it has been widely used in calculating the hydrodynamic characteristics of ships and their flow field distribution.Meanwhile,the flow field environment of double M-hull ship is more complex,and it is more difficult to study the details of its drag reduction mechanism and water and gas two-phase change by model test,so it becomes a good choice to study the sailing performance of double M-hull ship by using numerical methods.Based on the viscous CFD technology,this paper uses the commercial software STAR-CCM + to study the longitudinal motion stability of the double M-hull ship.The overlapping grid technology and DFBI module are used to simulate the 2-DOF motion of the double M-hull ship and the double M-hull ship with combined appendages in still water direct navigation and regular waves.The resistance,water-air two-phase characteristics and navigation attitude are analyzed to explore the influence of combined appendages on the longitudinal motion stability of the double M-hull ship.The main research contents include :(1)Grid independence verification and uncertainty calculation,compared with the towing test data,select the appropriate grid scheme and time step;(2)The numerical simulation of the double M-hull ship is carried out by using the above grid.The resistance,pressure,water-air two-phase distribution and stern wave are analyzed,and the water-air two-phase characteristics and navigation mechanism of the double M ship are summarized.(3)Based on the Stocks first-order wave model,a three-dimensional numerical tank is created to simulate the navigation motion of the double M ship in regular head sea waves.(4)Based on numerical simulation,the resistance,longitudinal motion stability and longitudinal motion stability in regular head sea waves of double M-hull ship are studied.The main factors affecting the longitudinal motion stability of double M-hull ship are analyzed.(5)The influence of combined appendages(channel hydrofoil + pressure wave plate)on the resistance,motion attitude and motion stability in regular waves of double M-hull ship in calm water is explored.Taking the resistance and motion response as the objective function and the installation parameters of the combined appendages as the independent variables,the installation parameters of the combined appendages suitable for the double M-hull ship are given.The research shows that the grid scheme and time step error determined in this paper are small,and the accuracy of the numerical scheme is high.Aiming at the longitudinal motion stability of double M ship in calm water and regular waves,the comparative study of bare ship and double M ship with combined appendages is carried out.The results show that the combined appendages can reduce drag and roll.At low speed,the stern flap plays a major role in suppressing the stern wave,reducing the pressure resistance and reducing the tail tilt.At high speed,the channel hydrofoil plays a major role in reducing the wet area of the bottom of the ship,reducing the friction resistance and improving the navigation attitude.According to the navigation performance of the double M ship,the optimal installation parameters of the combined appendage are given,which provides a certain reference value for the installation of the double M ship combined appendage.