Study On The Integrated Design Method Of The Rim-electric Driven Ducted Propeller

The Rim-Electric Driven Ducted Propeller(REDP)is a new type of integrated thruster which combines the Permanent Magnet Brushless DC Motor(BLDCM)with the ducted propeller.REDP is driven by motor,eliminating the intermediate transmission mechanism,having the significant characteristics of high power density,lightweight,compact structure,high integration,wide scope of application,thus it has broad market prospects.The paper proposes integrated design method,designs overall structure,the driven motor parameters and experiment scheme of REDP,optimizes the cogging torque and verifies REDP prototype.The experiment result suggests that the designed prototype meets requirements and provides certain theoretical and experimental references for further study on integrated moto r-driven propeller.The detailed research contents are as follows:First of all,the integrated design method of REDP is proposed including the design method of rim and blade,motor and overall structure.Take Ka4-50 series ducted propeller as prototype,use coordinated transformation method to get three dimensional airfoil data and encrypt it.Complete model construction of rim and blade by 3D design software.Conduct a detailed preliminary design on Permanent Magnet BLDCM by using equivalent magnetic and electric circuit.Besides two types of hub and hubless REDP are designed and compared.A 36 slots /24 poles motor is developed and its reluctance torque is found to be relatively high when the power is operated,which results from cogging torque.Secondly,in order to study the influence factors of the cogging torque,optimum design method and computer-assisted design method are used to analyze the effects of series combination of different slots and poles,tooth shape and arc coefficient on cogging torque and motor performance.The results show that thractional slot motor has definite advantages in reducing the cogging torque and the optimum combination of slot and pole series is 36/26,the slot shape is opening slot and the pole arc coefficient is 0.6.Thirdly,the Finite Element method(FEM)is used to analyze the performance of the final motor and obtain its performance parameters under different working conditions,which verifies the rationality of the motor design.Considering the influence of end winding on the driven motor,Simpolorer software has been applied in the field-circuit coupling analysis,the results show that the end winding hardly affects the finite element analysis result.Meanwhile,the field-circuit coupling analysis also lays a foundation for further driven control scheme design.Finally,it is difficult to measure the thrust and torque with the current open water dynamometer,therefore a measuring device and experimental method is designed and manufactured.The principle is that the thrust and torque can be indirectly obtained by using the thrust to make the structure produce micro-strain.The experiment mainly includes the measurement of thrust and torque at different speed,and obtains the open water characteristic curve of the REDP.The experiment result shows that the measured thrust at different speeds corresponds to the dimensionless thrust.It is proved that the REDP does not have a great influence on the performance of the original ducted propeller,and further validates the rationality of the prototype.