Three-dimensional Linear Cycloidal Propeller Performance Optimization Research Based On The CFD

With the rapid development of shipbuilding industry and Marine engineering, the requirements for the manoeuvrability of propulsions became higher and higher especially when the propulsions were applied to dynamic positioning systems and high-performance engineering ships.Compared to other marine propulsions, the cycloidal propeller has excellent manoeuvrability which can produce any direction and magnitude of thrust rapidly by changing the motion of the blade.In this paper, the three-dimensional study of cycloidal propeller hydrodynamic performance will be carried out based on CFD numerical simulation method to achieve the following purposes. The validity of CFD numerical simulation method is to be verified. To summarize the rule of which the cycloidal propeller hydrodynamic parameters change with the advance and eccentricity. The length and thickness of blade could be optimized and the influence of blade-tip plate on the three-dimensional viscous flow of cycloidal propeller could be obtained.To establish the CFD three-dimensional flow field model of cycloidal propeller based on the NSRDC experimental model. The results will be compared with the experimental ones.The change trend of them is same and the deviation is small. Then the validity of CFD numerical simulation method could be verified.Establishing the CFD model of three dimensional flow field which is based on the working principle of cycloidal propeller. The numerical simulation calculation could be carried out. Compared the results with the experimental ones to verify the model could capture the characteristics of cycloidal propeller flowfield accurately and quickly. Analyzing the laws belong to transient load of cycloidal propeller and single blade with variation of speed coefficient and pitch ratio. At the same time, drawing the coefficient of oscillation curves which are belong to the thrust and torque of the cycloidal propeller and its single blade.The corresponding relation between the change of the curve and the stability and reliability of the cycloidal propeller is summed up. The parameters above will be considered as the important performance evaluation parameters which may affect the stability and reliability of cycloidal propeller.To summarize the rule of which the cycloidal propeller hydrodynamic parameters change with the advance and eccentricity which played a positive role in strength calculation of propeller blade and the improvement of the performance of the structure design.The study to optimize the length and thickness of blade on the basis of above will be carried out. The numerically simulation will be carried out on the blade with different average length and thickness, length and thickness linear change along the blade. Then the numerical simulation results are analyzed. The study shows that the above parameters will impact the cycloidal propeller hydrodynamic performance. The results of optimization are as follows.The average chord represented by ratio of length and diameter is best within the scope of 0.176 to 0.262. The average thickness is best controlled in 12% chord length. The chord along the blade represented by ratio of the chord of root and slightly is best within the scope of 1.007 to 1.252. The thickness along the blade represented by ratio of the thickness of root and slightly is best bigger.During the process of cycloidal propeller’s operation, the fluid around blade-tip will flip from the pressure surface to suction surface. The blade-tip vortex will be formed which affect the performance of the propeller. An optimization method is put forward in this paper which is adding blade-tip plate to the blade. Studing the influence of blade-tip plate on the three-dimensional viscous flow of cycloidal propeller, and the conclusion could be obtained that the blade-tip plate can weaken the blade-tip vortex and optimize the hydrodynamic performance of cycloidal propeller.