Effect Of Motion And Different Design Parameters On Hydrodynamic Performance Of Ducted Propeller In An Underwater Vehicle System

In this paper,computational fluid dynamics(CFD)approach and multiple sliding mesh technique are applied to observe the effect of motion and different design parameters on hydrodynamic performance of ducted propeller in an underwater vehicle system.From the individual ducted propeller expands to the case with the main body of the underwater vehicle,and then expands to a numerical analysis of the hydrodynamic characteristics and flow field around various types of ducted propellers in an underwater vehicle system from the analysis of the tip vortex generation mechanism and the improvement method in the individual ducted propeller.The main research results are as follows:(1)When the individual ducted propeller is in a yaw motion,the thrust is symmetrical and more thrust clockwise than when counterclockwise.(2)The induced velocity components,induced velocity and thrust follow such a relationship when consider the yaw motion of an underwater vehicle,in a given rotation speed of the propeller,as far as the whole ducted propeller,the smaller the advanced velocity,the greater the thrust issued by the propeller;the value of axial induced velocity decreases,pressure increases behind the propeller disk at the blade tip because of the excitation of tip vortex in the exit of the duck,which results an increase of pressure difference between the face and back of propeller blades;the thrust distribution along the radial direction of blades manifests a feature that the greater the relative radius,the greater the thrust.(3)By increasing the angle of attack and lengthening the length of the duct,the vortex at the tip of the propeller blades is improved effectively,and the pressure distribution on the blades back and face is more uniform.When the inlet velocity coefficient of the ducted propeller is near 0.4,the distribution of the thrust shares on the duct and the blades is reasonable,and the ducted propeller has the higher efficiency.(4)The vortex at the tip of the propeller blades is differs greatly when the underwater vehicle system with different ducted propellers,further more,when the system yaws at different location,the tip vortex strength is also different,the smallest location is ? = 30°.As for the tip vortex,the ducted propeller which has increased the angle of attack and extended the length of the duct shows a better performance.Through simulate precisely the characteristics of flow field around the ducted propeller and the relationship between the various components of velocity and thrust distribution on the propeller disk is helpful to enhance the understanding of the thrust mechanism issued from a ducted propeller.Also a method to improve the tip vortex and stability of the ducted propeller is proposed,all these are helpful to provide a theoretical guideline to design a better performance underwater vehicle system.