Numerical Simulation And Airfoil Optimization Of Polar Cruise Rudder Based On CFD

In recent years,the rapid development of polar tourism has increased the demand for polar cruise ships,but the hostile environment has put forward exacxting requirements on ship design,construction,navigation and environmental protection.As the main tool for developing tourism resources,polar cruise ships have high standards for comfort,safety and ice-breaking capability.Currently,only Norway,Finland,and Russia have mastered the ship design and construction technology.Now China is in its infancy in this regard.Our first polar cruise ship with independent intellectual property rights was successfully launched in 2017,which setting a precedent for domestic research.As the key equipment in the deck machinery of polar cruise ships,the rudder is one of the main equipments to implement the manoeuvrability of the ship.The cruise ships sailing in polar regions,due to the influence of ice floes and the environment.The main focus is on maneuverability,and the other is on stability.Moreover,the impact of the ice floes to the strength of the rudder blades needs to be considered.Therefore,the selection of rudder needs to consider a variety of factors.The main research contents of this paper are as follows:(1)Investigate the current ownership of polar ships at home and abroad,summarize the ice class classification of various classification societies and the requirements of the polar ships.Comprehensively consider the environmental conditions and equipment compatibility of cruise ships,and explore the selection of rudder in combination with the shipyard’s requirements.According to the principle of type,clarify the key points of rudder selection for polar cruise ships,and determine the type selection strategy with maneuverability as the main factor and stability as the supplement.(2)The hydrodynamic numerical simulation of three rudder blade airfoils is carried out based on CFD technology.The lift coefficient and pressure coefficient are obtained through model construction,flow field design,mesh division and fluent simulation.Combined with the velocity vector diagram and pressure cloud diagram under different rudder angles,NACA 0020 is selected as the basic airfoil according to the simulation results,type selection principles and real ship examples.(3)NACA 0020 airfoil is parameterized based on CST and Hicks Henne parameterization method.Aiming at the discontinuity of airfoil trailing edge fitting in the traditional Hicks Henne method,the airfoil fitting effect of rudder trailing edge is improved by adding profile function.The NACA 0020 airfoil is fitted based on the CST method of different Bernstein polynomial orders.The CST method and the improved Hicks-Henne method are compared with the fitting effect and the number of parameters,and the 6th-order CST method is used to express the airfoil parameterization.(4)Particle swarm optimization is used to optimize the hydrodynamic performance of the parameterized airfoil with lift-drag ratio and pressure coefficient as optimization goals.The lift-drag ratio is optimized based on the single-objective particle swarm algorithm,and the lift-drag ratio and pressure coefficient are optimized based on the multi-objective particle swarm algorithm.The optimization results show that compared with the CFD numerical simulation,the two algorithms achieve the optimization goals of increasing the lift-drag ratio and decreasing the pressure coefficient.Proving the feasibility of optimizing the hydrodynamic performance of the rudder blade by particle swarm optimization,and providing a theoretical reference for the design and selection of the rudder.