Research On The Problem Of Fluid And Thermal Coupling Field In Deepwater Permanent Magnet Motor

With the increasing of Marine projects in China,the level of Marine science and technology has been developed rapidly,and the application of underwater motor has been more and more extensive.Different from the motor in the air,the underwater motor has to deal with special problems such as pressure and erosion,and its heat production and heat dissipation conditions are also different from the motor in the air,which will generate a lot of heat.At the same time,due to the limitation of working conditions,the underwater motor can not be maintained at any time,resulting in its temperature rise problem is particularly prominent.Therefore,the deepwater motor's loss and fluid field and temperature field are detail research in this paper.Firstly,for the electromagnetic losses in the motor,a two-dimensional calculation model of the motor was established.Ansoft Maxwell simulation software was used to calculate the transient field of the motor,and the copper,iron and rotor eddy losses in the deepwater permanent magnet motor were obtained.Secondly,established a three-dimensional model of the fluid in the motor and analyze the characteristics of the fluid flow in different flow states of the air gap fluid,and analyze the influence of different tooth structure on the fluid flow state of the air gap.To end fluid,due to its complex structure,fluid flow easily evolve into turbulence,so end fluid in turbulent flow condition for the simulation calculation.The velocity change cloud and streamline diagram of end fluid are obtain,and extract the tangential,radial and axial velocity components of the end fluid along the axial direction,and the calculation results are analyzed in detail.On this basis,the fluid friction losses on the rotor surface and end face are calculated respectively,and the influence factors such as rotation speed,temperature,pressure,wall roughnessand number of tooth grooves on fluid friction losses are analyzed.In addition,the difference between the formula method and the computational fluid dynamics(CFD)method in the calculation of fluid friction loss is compared and analyzed in the case of the change of rotational speed.Finally,in order to study the temperature field of the deepwater oil-filled permanent magnet motor under rated load,the actual windings and insulation of the motor are equivalent treated and the equivalent thermal conductivity is calculated and established the three-dimensional model of motor in this paper.And in order to fully consider the influence of convective heat dissipation on the accurate calculation of temperature field,the fluid field model of inner and outer motor was established.According to the basic assumptions and the set of boundary conditions,the fluid and temperature filed in the computational domain were directly coupled calculated with finite volume method(FVM).The flow characteristics of the fluid field and the heat transfer coefficient distribution characteristics of the motor outer surface,rotor surface,stator surface and the tooth groove surface are obtained.The temperature distribution characteristics of each part of the motor are obtained.And the simulation results are analyzed in detail and some useful conclusions are obtained.