Numerical Simulation And Analysis Of Fluid Properties In Large Turbo-generators

With the rapid development of science and technology and the improvement of people’s living standards,the demand for electrical energy in all walks of life has gradually increased.Clean energy sources such as geothermal energy and wind energy are still unable to meet people’s growing demand for electricity in a short period of time.Therefore,thermal power generation still plays a very important role in the production of electricity.Turbo-generator are important equipment for electromechanical energy conversion.Among many types of turbo-generator,air-cooled turbo-generator have been widely used in the thermal power industry in recent years due to their simple structure and low maintenance costs.However,as the internal loss and thermal load of the generator gradually increase,the internal temperature rise of the generator is increasing,which seriously threatens the safety of generator operation.Therefore,it is necessary to investigate the flow law of the cooling medium in the generator and accurately simulate the distribution of the flow field in the generator,so as to further improve the design of the generator cooling system and improve the performance of the generatorFirstly,this paper takes a 350 MW high-power air-cooled turbo-generator as the research object.Based on the theory of electrical machinery and computational fluid dynamics,combined with the structural characteristics of the generator and the characteristics of the actual ventilation and cooling structure,a three-dimensional physical model of the generator is established,and then based on the physics of the generator For the symmetry of the model and cooling system,a 1/4 numerical solution model of the generator is obtained.Secondly,the boundary conditions for solving the mathematical model are given.Aiming at the local excessively high fluid velocity in the turbo-generator,the incompressible and the compressible fluid model are used respectively,and the finite volume method is used to numerically calculate the fluid field in the generator,and then the cooling medium in the fan,rotor and stator regions is analyzed and compared.The distribution of fluid parameters such as flow and velocity reveal the influence of fluid compressibility on the rheological properties of fluid in generators.By comparing the calculation results of different models with the design values of the flow rate in each area of the generator,the correctness of the solution and the calculation results using the compressible fluid model is verified,which lays the foundation for the structure optimization of the generator.Finally,in order to solve the problem of uneven flow rate distribution in the sub-slots caused by the rotation of the rotor,an optimization scheme of adding a baffle at the end of the rotor and changing the baffle of the wind zone at the end of the rotor is proposed,and then the compressible fluid model is used to numerically simulate the fluid field of the optimized generator.,focusing on the comparative analysis of the flow and velocity distribution of unoptimized and optimized rotor sub-slots,and the optimal scheme is obtained.The conclusions obtained are accurate calculation of the fluid field in the high-power air-cooled turbo-generator and ventilation cooling.system optimization design has certain theoretical value and practical engineering significance.