Analysis Of Rotating-guide-bar Eccentric-disc Cycloidal Propeller Mechanism

Cycloidal propeller is a special propulsive device, which can be used as the main or auxiliary thruster of surface ships, submarines or aircraft. The blades of cycloidal propeller are straight wings,each axis of which is parallel to the propeller shaft. Each blade rotates around the shaft while around its own axis. When the ship moves in a certain advance coefficient,the trajectory of points in the blade’s axis is cycloid. Cycloidal propeller can produce thrust of any direction in the plane without a rudder, while magnitude and direction of the thrust can change rapidly and accurately.Aiming at the shortcomings of present cycloidal propeller,this article presents a rotating-guide-bar eccentric-disc cycloidal propeller mechanism. The rotating-guide-bar mechanism is adopted to make the blades of cycloidal propeller move as Normal Intersection Law, and the eccentric-disc amplifier is adopted to reduce the slippage of the rotating guide bar to enlarge the eccentricity.This paper analyzes the kinematics and dynamics of the rotating-guide-bar eccentric-disc cycloidal propeller mechanism, also how the clearance of kinematic pair influences the error of blade angle.According to the kinetic characteristic of the rotating guide bar, the relationship between the angle velocity and acceleration of the blade and the angular trajectory of the spindle has been obtained. The magnifying function that eccentric disk does to the eccentricity is illustrated through theoretical analysis. The features of slider coupling, synchronous belt transmission mechanism and Schmidt coupling are compared when to realize the synchronous rotation of the eccentric disk and the spindle. To realize any-position adjustment of the eccentric point in the plane, a polar-coordinates operating mechanism of eccentric controlling point is designed.The dynamics analysis of the mechanism and the analysis of hydrodynamic performance of the blades are conducted, aiming at working out the driving torque of the rotating-guide-bar eccentric-disc cycloidal propeller. The fluid force sustained by the spindle of the cycloidal propeller and by the axises of the blades are obtained by simulation. Kinetic equations of cycloidal propeller are built by dynamic equivalent model, when rotary inertia of all moving parts are equal to the principal axis.Whether the motion law of the blades is correct directly affects the efficiency of the cycloidal propeller. Aiming at the control part and the polar-coordinates operating mechanism of eccentric controlling point part of the rotating-guide-bar eccentric-disc cycloidal propeller ,the analysis of the impact that each kinematic pair clearance does to the angular and positional error of the circle’s center of the eccentric disc is conducted, and the affecting law that the angular ane positional error of the circle’s center of the eccentric disc does to the blades’angular error is obtained.A driving system of the cycloidal propeller mechanism is presented. A vibration measurement instrument is applied to test the vibration performance of the cycloidal propeller.The mechanical noise of the cycloidal propeller and the hydrodynamic noise of the blades are respectively tested in cavitation tunnel.