Optimization Design Method Of Shaftless Propeller Based On Response Surface Model

Shaftless propeller is an advanced and novel propulsion device in ship power system.Different from the traditional propeller,the shaftless propeller abandons the traditional shafting structure in structure,and directly connects the propeller blades and the motor through the rotating ring.Because of such structural characteristics,the shaftless propeller has the characteristics of large space utilization,high propulsion efficiency and good concealment.In this paper,the three-dimensional model of the shaftless propeller is built,and the hydrodynamic performance prediction test of the shaftless propeller is carried out by using CFD calculation method,and the optimal design scheme of the shaftless propeller is completed through the response surface model test of the design parameters.In this paper,taking Ka propeller + No.19 A duct as an example,three-dimensional modeling is carried out in UG,CFD calculation is carried out in STAR-CCM+ software,and the calculated results are compared with the test values.It is found that the data similarity is good,which proves the correctness of the calculation results,and also verifies the feasibility of using CFD calculation method to predict the hydrodynamic performance of propeller.Then,according to the calculation example of ducted propeller,the hydrodynamic analysis of shaftless propeller is carried out.Four design parameters,pitch diameter ratio,sideslip angle,caster angle and tip diameter ratio,are selected to calculate and analyze the influence trend of each parameter change on the hydrodynamic performance of propeller.The results show that the change of pitch diameter ratio has the greatest influence on the hydrodynamic performance of shaftless propeller,the second is the angle of sideslip,the third is the angle of caster and the diameter ratio of inner circle.The influence trend is: the increase of pitch diameter ratio will increase the thrust coefficient,torque coefficient and open water efficiency;the increase of side angle will decrease the thrust coefficient,torque coefficient and open water efficiency,but the effect is not obvious;the influence of caster angle and inner circle diameter ratio on thrust coefficient,torque coefficient and open water efficiency is not obvious.Finally,the response surface model is established for four parameters.Through the variance analysis of the response surface model,the quadratic multiple regression model equation is obtained,and the optimal process conditions are obtained through the optimal condition test.Through the numerical simulation calculation,it is verified that the results are consistent with the response interview on the prediction value of the open water efficiency,which shows that the equation can truly reflect the impact of various factors on the open water efficiency.