Research On Hydrodynamic Performance Of Flap Cycloidal Propeller

Cycloidal thrusters can quickly and accurately generate the thrust required by the ship,and ensure the ship has better control performance at low speed without relying on the rudder.Flaps were first introduced in the development of aviation airfoils,and are often called trailing flaps because they are placed behind the wing.The designer can adjust the lift of the wing by changing their motion pattern.In this thesis,the flap is added to the tail end of the blade of cycloidal propeller according to the idea that the vertical axis fan can improve the aerodynamic performance by introducing the flap,and the influence of the flap structure parameters on the hydrodynamic performance of cycloidal propeller is discussed.The difficulty of studying the hydrodynamic performance of cycloidal propeller lies in how to correctly simulate the complex superimposed motion of its blades.In this thesis,STAR-CCM+ overlapping grid technology is used to simulate blade motion.NACA 3412 airfoil,which is similar to the airfoil in NSRDC,is selected as the model to verify the simulation method.After setting appropriate turbulence model and boundary conditions,a simulation scheme is established.Both errors are within the allowable range of engineering,which verifies the validity and accuracy of the simulation method in this thesis.Based on the above simulation method,the NACA 0012 airfoil blade designed in this thesis is simulated and calculated.The variation law of thrust coefficient and torque coefficient of cycloidal propeller with eccentricity and advance coefficient is obtained.The force variation law of blades with different initial phase angles at any time is summarized.Secondly,the open water performance of flap cycloidal thruster was simulated by using eccentricity and advance coefficient as the research scale,and the structural parameters of flap were changed.The research parameters include flap seam,flap length and flap deflection Angle.The thrust coefficient,torque coefficient,side thrust coefficient and open water efficiency of cycloidal thruster under the combined condition of eccentricity and advance coefficient are obtained.The influence of each structural parameter of flap on the performance of cycloidal thruster is analyzed.At the same time,the flap deflection Angle corresponding to the maximum increase of cycloidal thruster efficiency and the variation amplitude of hydrodynamic performance coefficient under different eccentricity and advance coefficient are summarized.Finally,the self-propelled performance of the flap cycloidal propeller coupled with the hull is simulated numerically by the established numerical simulation scheme.The flap cycloidal propeller with eccentricity e=0.7 was selected for the propeller model,and DTMB5415 was selected for the hull.After adjusting the size of the propeller model,the selfpropelled numerical model was established to determine the self-propelled simulation method.The accuracy of the self-propelled numerical simulation method was verified by comparing the calculated results with the experimental values.Based on this method,the self-propelled point was found at the design speed of the ship model,and the hydrodynamic parameters of the flap cycloidal propulsive under the self-propelled point were analyzed.The actual propulsive efficiency of the coupling between the flap cycloidal propulsive and the ship hull was obtained,and the coordination between the flap cycloidal propulsive and the ship hull was obtained,which provided a reference for further research on the coupling performance of the flap cycloidal propulsive and the ship hull.