A Study On Heat Transfer Enhancement Of Spiral Tube In Water-cooled Jacket Of A Canned Motor

For the shield motor with built-in heat exchanger,the secondary water plays an important role in the cooling of shell and primary water.If the primary water cooling effect is poor,it will lead to over temperature of internal components and affect the safe operation of the motor.Therefore,it is of great significance for the safe operation of the motor to explore the heat transfer in the cooling jacket and then enhance the primary water heat transfer in the spiral tube.Aiming at the spiral tube in the water-cooled jacket of the outer casing of a canned motor,based on computational fluid dynamics(CFD)and enhanced heat transfer theory,the finite volume method is used to study the fluid flow and heat trans fer performance in the spiral tube.First,a three-dimensional physical model including the simplified casing and the internal spiral tube of the water-cooled jacket is established and meshed.The RNG k-? is used in the numerical simulation,and the boundary conditions are given in combination with the actual conditions of the project.The accuracy of the results is verified by comparing the experimental correlation of the drag coefficient with the simulation value.The velocity field,temperature field and heat transfer performance of the water pipe inside and outside the spiral tube in the water-cooled jacket are simulated.The results show that secondary flow is generated in the water pipe both inside and outside of the spiral tube.Secondly,on the basis of the same structure and other boundary conditions,the inlet velocity of primary water in the spiral tube was changed,and the effect of the Reynolds number of primary water inlet on the fluid flow and heat transfer in the spiral tube was investigated.The relationship between the water inlet Reynolds number;in the same way,the effect of the secondary water inlet Reynolds number on the heat transfer of the spiral tube was investigated,and the optimal secondary water inlet Reynolds number was 8000.Finally,in order to explore the influence of the cross-sectional shape and cross-sectional area of the spiral tube on the flow and heat tran sfer of the primary water in the spiral tube,first,the cross-sectional shape of the spiral tube was changed on the premise that the primary water cross-sectional area in the spiral tube was unchanged.Flow and heat transfer performance of a rectangular structure and a circular structure with different aspect ratios.Furthermore,in order to study the influence of the cross-sectional area on the heat transfer of the spiral tube,the aspect ratios of the three rectangular cross sections were enlarged in equal proportions so that the equivalent diameter was the same as that of the circular structure,and the flow and heat transfer situation at this time were investigated.In addition,the field synergy theory is used to analyze the field synergy performance at different cross-sectional shapes and cross-sectional areas,and the effect of cross-sectional shape and area on the heat transfer in the spiral tube is analyzed from the perspective of field synergy.The results show that the heat transfer performance of the circular section is the best.In the rectangular section,the larger the characteristic size a,the better the heat transfer performance.In addition,the larger the cross-sectional area of the primary water in the spiral tube,the better the heat transfer performance inside the spiral tube.In this paper,the optimal inlet Reynolds number was explored,and the influence of the cross-sectional shape and area of the spiral tube on the heat transfer performance of the spiral tube was discussed.The structural design and performance of the spiral tube inside the water-cooled jacket of the canned motor were discussed.And provide reference and basis for improvement.