Parameter Analysis And Open Water Experiment Design Of Light Rim Thruster

Rim-driven propulsion is a new type of marine propulsion system.It has the characteristics of high propulsion efficiency,good flexibility,small hull space occupation,light weight,and good vibration and noise performance.In this paper,the relevant parameters of the duct,propeller and drive motor of the light shaftless rim thruster will be studied and the open water experimental design will be carried out.In the first part this paper,a set of Python programs are developed for the rounding processing of the leading and trailing edge of the propeller and the coordinate transformation of the blade.The Ka4-70 propeller is modeled and the19 A duct is used to verify the open water dynamic numerical calculation method using ANSYS-CFX.The experimental values are compared to verify the accuracy of the data method in this paper.A set of relatively optimal grid parameters is obtained for subsequent calculations.In the second part,the conventional propeller is slightly too thin,and the strength cannot meet the problem of the thrust torque transmitted by the blade of the rim propeller.On the basis of Ka4-70 propeller,three different airfoil sections are designed,and the radial thickness distribution is opposite to that of the Ka propeller.The open water performance is analyzed and it is found that the increase of the airfoil thickness of the high-radius section of the blade will lead to the increase of the blade thickness.The surface pressure distribution is abnormal;the bow-shaped and thick airfoil at high radius will increase the torque of the blade by about 0.02 at each advance coefficient,but the thrust is basically equal,resulting in a decrease of 3.4% in the maximum efficiency of the propeller;the shuttle-shaped airfoil will make the blade The axial force and radial force are reduced at the same time,and the highest efficiency is not much different from that of the bow-shaped airfoil propeller;the wing airfoil with higher lift resistance at low attack angle is2.4% more efficient than the bow-shaped airfoil propeller,and the efficient working area is increased.Removing the propeller hub has only a 1% increase in the open water efficiency of the propeller,which has a small impact.In the third part,on the basis of the 19 A duct,a variety of ducts suitable for the thruster were designed,and the influence of the h eight of the leading edge and the trailing edge of the duct on the open water performance of the thruster was studied.The change of the height of the leading edge and the trailing edge of the duct has a greater impact on the propeller;the height of the l eading edge has little effect on the performance of the whole machine within a certain range;if the outer wall of the trailing edge is too high or too low,fluid separation will be formed at the tail,reducing the efficiency of the propeller;the duct The more the inner wall of the trailing edge expands outward,the greater the loss of propeller efficiency;the greater the advance coefficient,the greater the influence of the duct on the open water performance of the propeller.In the fourth part,according to the analysis and calculation of the propeller and the duct,the permanent magnet brushless motor of the thruster is designed,and the influence of the relevant parameters of the motor on its performance is studied by numerical calculation method.When the thickness of the motor iron core increases from 0.5mm to 7.5mm,the cogging torque increases first and then tends to be stable.The motor efficiency reaches a maximum of 81.8% under the thickness of the 1.5mm iron core,and then begins to decrease due to the increase of the cogging torque.and tends to a stable value of 77.7%;when the pole arc coefficient is 0.37,the motor has high efficiency and small cogging torque;the stator split ratio has little effect on the motor performance;the Halbach arra y can effectively improve the motor air gap flux density and Reduce cogging torque.Finally,the processing of the propeller,motor,and conduit of the propeller was completed;a series of bearings were researched and produced,and it was found that the conical bearing has a simple structure but high requirements on materials and dimensions,and the ball-needle bearing has a complex structure but has the smallest friction,which can be used for propulsion.The device experiment was completed;the open water experiment design and device development were completed.