Research On Resistance Reduction Optimization And Seakeeping Performance Of Offshore Wind Power Operation And Maintenance Catamaran Based On CFD

The working area of offshore wind power operation and maintenance catamaran is usually rough and the sea conditions are relatively bad.The operation and maintenance catamaran should have excellent rapidity and wave resistance when performing fan maintenance tasks.Catamaran has two hulls,a wider deck area,and its hydrodynamic performance is better than that of monomer ships.Currently,catamaran is one of the main ship types for offshore wind power operation and maintenance.Therefore,it is of great significance to optimize its rapidity and seakeeping.In this paper,a domestic 28 m catamaran wind power operation and maintenance ship was taken as the research object,aiming at reducing its sailing resistance and reducing its pitch and heave motion when sailing against the waves,the method of installing stern flap at the stern of the catamaran was adopted to improve the speed and wave endurance performance of the catamaran wind power operation and maintenance catamaran.The CFD numerical simulation software FINE/Marine was used to numerically simulate the resistance performance of catamaran ships.Through the analysis of the numerical simulation results and the proportion of total resistance components,it can be seen that the wave resistance of a catamaran at medium-high speed is much greater than the viscous resistance.The install stern flap can play a better role in the drag reduction optimization of catamaran operation and maintenance ships.The numerical simulation of catamaran equipped with 5 kinds of push down angles is carried out.Through the comparison and analysis of the calculation results of bare hull model and the optimized hull model,it is found that the 5 kinds of push down angles can greatly reduce the catamaran’s sailing resistance,and the 10° push down Angle is the best one.Based on the optimal drag reduction Angle Stern flap,the influence of the length and vertical installation position of stern flap on hull navigation resistance is further studied by single factor test in a certain range.Through calculation,it can be concluded that the larger the length of the stern flap in a certain range,the better the drag reduction effect.When the length exceeds a certain length,the friction resistance will be increased due to the increase of the area of the stern flap,so as to reduce the drag reduction effect.When the length of the stern flap is unchanged and the vertical installation position is gradually deepened downward,the drag reduction effect becomes worse as the vertical installation position of the stern flap is further and further away from the design water line.Finally,CFD method is used to calculate the pitch motion response and heave motion response of a catamaran with bare hull and a catamaran with 10° push down Angle stern flap with relatively good resistance performance under three speeds and 10 different λ/L(wavelength to length ratio)conditions.Through the comparative analysis of the calculation results,it is found that the install stern flap can effectively reduce the sailing resistance of catamaran,but also can improve the pitch and heave motion of the hull,and has a certain optimization effect on the seakeeping performance.The research results and conclusions of this paper can provide experience and reference for the optimization design of speed and seakeeping of offshore wind power catamaran operation and maintenance ship.