Mechatronic Design And Application Research Of Shaft-less Rim-driven Thruster

In recent years,with the rapid development of maritime trade in various countries,the traditional propeller propulsion method has revealed the problems of difficult maintenance and low efficiency,and people turn their attention to the new propellershaft-less rim-driven thruster(RDT).RDT has the advantages of low space requirement,low cost of shaft system construction,flexible installation position,light weight,and small size.In this paper,the effect of the number of blades and the geometric parameters of the duct on the hydrodynamic performance of the RDT are studied,and RDT is designed according to the effect laws.An experimental analysis of RDT was carried out on a designed test bench,and the combination of RDT and unmanned boat formed a high-speed unmanned boat.The numerical calculation of the ducted propeller is carried out by Computational Fluid Dynamics to verify the feasibility of the numerical calculation method.Numerical investigations were performed to the study the effect of blade number on the hydrodynamic performance of RDT with certain blade area ratio and pitch ratio.The results demonstrate that the thrust coefficient and torque coefficient of the RDT increase with the blade number at a certain advance coefficient,but the efficiency of the RDT decreases with the increase of blade number.The 7-blade RDT has higher thrust and torque than the 3-blade RDT due to the large friction and pressure difference between the suction and pressure surfaces at a certain advance coefficient.In order to choose a larger efficiency and higher thrust,the number of propeller blades is determined as 4.The effect of the thickness of the duct,the radius of the leading edge of the duct and the geometry of the trailing edge of the duct on themselves are investigated and analyzed.The conclusion shows the thrust coefficient increases with the thickness of the duct decreasing,however the torque coefficient increases with the increase of the thickness of the duct,so the efficiency increasing with the decrease of the thickness of the duct.On the other hand,the radius of the leading edge of the duct has no significant effect on the thrust coefficient of the RDT.However,the torque coefficient of RDT decreases with the increase of the radius of the leading edge of the duct,so the efficiency of RDT increases with the increase of the radius of the leading edge of the duct.A comprehensive comparison shows that the RDT 15-0.5(the duct thickness is 15,the ratio of the radius of the leading edge of the duct and the duct thickness is 0.5)has the best hydrodynamic performance among the investigated RDT models in this work.The RDT is designed by integrating the laws of the number of propeller blades and the geometric parameters of the duct.The thrust performance of the RDT at different speeds is tested,and the actual power is obtained according to the voltage and current.Carry out the RDT "water grass" passing test,combine the RDT with the unmanned boat,and determine the installation mode and position of the RDT.The RDT can not only provide power during the acceleration process of the unmanned boat,but also make use of the advantages of the RDT to make up for the shortcomings of the unmanned boat,thus forming a high-speed unmanned boat.