Research On Hydrodynamic Performance Of Dragon Boat Based On CFD

With the holding of a series of competitions such as the Dragon Boat World Cup and the Asian Games,athletes from other countries have achieved good results in these competitions,making the dragon boat competition more intense.Good competition performance is related to physical fitness and tactical training on the one hand,and depends on the hydrodynamic performance of the dragon boat body on the other hand.However,the current physical fitness and tactical training has limited space for further improvement after years of development,so the hydrodynamics of the boat body Performance has become the key to affecting competition results.Existing dragon boat hydrodynamic performance research methods usually use boat model tests for performance research,which requires a long time and high costs and many limiting factors.The use of computational fluid dynamics(CFD)technology can effectively simulate the various postures and mechanical characteristics of the dragon boat in the actual sailing process,overcome the conditional limitations of the model test and shorten the test time,which is of great significance for studying the hydrodynamic performance of the dragon boat.In this paper,the hydrodynamic performance of the dragon boat is studied by a combination of experiment and numerical simulation calculation.With reference to the theory of ship fluid mechanics,the type of resistance and the cause of formation during the dragon boat sailing process are analyzed;based on the similar plate theory and the sailing attitude parameters of the boat,the resistance characteristics of the dragon boat are preliminarily predicted,and the resistance of the dragon boat body at different speeds and inclination angles is obtained.According to the characteristics of the movement and force during the dragon boat’s navigation,the models of the inertial force and moment of inertia formed by the change of the human propeller’s attitude were established,and the models for the direct and rolling motion of the dragon boat in still water were established and analyzed.The relationship between the attitude of the boat body and the inertial force and moment of inertia of the human propeller and the force and moment of the water flow on the boat body;through the simulation test of the inertia force of the blade propeller hand,the peak inertial force during the rowing process is obtained and according to the boat body The size,combined with the static water direct navigation and roll motion models,obtains the moment of inertia of the blades and propellers when the boat rolls and pitches,which provides a basis for the numerical simulation analysis.Using a combination of experiment and simulation,the FLUENT software is used to simulate and analyze the direct navigation of the dragon boat in still water to explore the influence of speed and inclination on the resistance,restoring torque,pressure distribution at the bottom of the boat and free liquid surface during the pitch motion of the dragon boat,And compare and verify the numerical simulation resistance with the predicted resistance result.Then,the relative analysis of the rolling motion of the dragon boat is carried out.The dynamic grid technology is used and the external custom function(UDF)is used to study the influence of the moment of inertia and the forced rolling parameters on the rolling motion of the boat.The results show that:the rolling period The shorter,the greater the amplitude,the greater the rolling moment of the boat;when the moment of inertia is the same,the longer the action period,the greater the amplitude of the boat roll angle;the shorter the action period,the greater the dynamic lift of the boat,The smaller the heave amplitude.Finally,according to the characteristics of the boat roll motion,the influence of the installation of the bilge keel on the boat roll motion is analyzed.The results show that the increase of the bilge keel can effectively improve the amplitude of the boat roll motion under the action of the moment of inertia.The method and content proposed by the Dragon Boat Hydrodynamics Research Institute in this paper can provide reference significance for the follow-up dragon boat performance research.