Research On Hydrodynamic Characteristics Of Cycloidal Propeller Considering The Influence Of Hull

Cycloidal propeller,as a kind of special marine propeller,has good maneuverability,so it is widely used in various fields of marine engineering equipment.By changing the position of the eccentric point,the cycloidal propeller can produce forces in different directions to realize in-situ rotation,translation and other operations.Its good maneuverability has great application value for tugs,ferries and other ships with high mobility requirements.Cycloidal thrusters are usually installed at the bottom of the ship perpendicular to the waterline surface of the hull.Their motion is composed of revolution around the center point of the propeller and rotation around the blade itself.Due to the large number of blades,the hydrodynamic interference between the blades is very complex.After increasing the hull,the existence of the wake of the hull aggravates the complex interference between the blades.Based on the special combination between cycloidal propeller and hull,the influence of hull waterline shape on the hydrodynamic performance of cycloidal propeller can be explored by two-dimensional method.Studying the hydrodynamic performance of cycloidal thrusters with different ship shapes and different installation positions has important engineering guiding value for the design of cycloidal thrusters and the matching of appropriate ship types.In this paper,CFD method is used to calculate the hydrodynamic performance of cycloidal propeller under the influence of open water and hull.The overall work is summarized as follows:This paper briefly expounds the engineering practical significance,theoretical and experimental research process and application status of cycloidal propeller,puts forward the idea of using two-dimensional method to study the hydrodynamic characteristics of cycloidal propeller under the influence of open water and hull,and gives the overall framework of the paper.On this basis,the motion principle,control equation and hydrodynamic calculation formula of cycloidal propeller are introduced,and a simple cycloidal propeller model is constructed.Based on the convergence analysis of grid and time step,after determining the appropriate calculation strategy,the variable parameter analysis of cycloidal propeller under the influence of open water and hull is carried out respectively,The variation law of hydrodynamic performance of cycloidal propeller under different motion parameters is studied.Then,the hydrodynamic performance curve of open water cycloidal propeller is compared with that of considering the influence of hull under the same parameters to study the specific impact of adding hull on the propeller.The results show that under the same eccentricity and inflow velocity,increasing the hull will increase the amplitude and amplitude of the main thrust and torque of the cycloidal propeller,and change the direction of the lateral thrust.After getting the influence of adding the hull on the cycloidal propeller,change the fullness of the hull and the installation position of the propeller,and study the hydrodynamic performance of the cycloidal propeller with different fullness and different installation positions.By comparing the flow field,vorticity field and pressure distribution under different working conditions,the reasons for the change of hydrodynamic performance are explored.The results show that the higher the fullness of the hull,the difference between the high-speed region and the low-speed region of the propeller wake flow field increases,and the thrust and torque increase.When the cycloidal propeller moves from the original position to the bow,stern,midship and both sides of the hull,the influence on the hydrodynamic performance of the cycloidal propeller is different,and the change of the lateral position of the cycloidal propeller has a greater influence on the hydrodynamic performance.