Numerical Simulation Study On Heat-Fluid Coupling Temperature Distribution Of The Medium And Small Bulb Turbine Generator

In order to develop and utilize low head and ultra-low head hydropower resources,medium and small bulb turbine generators are set to be the best choice.However,such a kind of generator is restricted to its mounting space.Compared with other types of hydroelectric generator,the structure of the medium and small sized bulb turbine generator is much more compact,ventilation and heat dispersion condition is much worse.As a result,this kind of generator has a higher temperature rise,which seriously affects generator's normal service life and running reliability.Therefore,the temperature distribution needs to be well calculated and analyzed throughout the process of generator's design and manufacture.However,in the past,the calculation of generator's heat loss and internal temperature mainly rely on traditional formula and design experience,which can not describe the temperature field distribution accurately.In this paper,the numerical simulation method is used to calculate and analyze the temperature field of the generator from the point of view of heat loss,multi-physics coupling field and optimization of ventilation and heat dissipation structure for a certain type bulb turbine generator.First of all,according to generator's basic structure parameters,two-dimensional geometric model and electromagnetic fields(EMF)finite element analysis model is established.Boundary conditions and excitation parameters of testing and rated working condition are set respectively.Calculate the time-averaged core loss of the original and two kinds of modified structures of the part stator using EMF finite element method.Secondly,based on theories of heat transfer,computational fluid dynamics and coupling of multi-physics,three-dimensional model of the generator for heat–fluid coupling temperature analyzing is set up.By using the time-averaged core loss calculated by EMF finite element analysis and the copper loss of the coil defined by User-Defined Functions,temperature distribution is revealed under test working condition.Combine with actual test data to verify the accuracy of the boundary conditions imposed.On this basis,temperature distribution under rated condition is calculated and analyzed.Discussed the different inlet cooling wind velocity and whether there exists vents on the yoke effect on the highest temperature rise of different components.Optimization attempts such as setting grooves in the tooth of stator,increasing section of stator coils and decreasing yoke's vents appropriately are carried out.Based on these,numerical calculations are accomplished and contrast data are analyzed.Finally,stator ventilation structural parameters(four parameters including the size and position of the yoke vent and teeth groove)have been optimized based on Design of Experiment method and optimization theory.Obtain the optimum parameters of the stator ventilation structure in the final,which further decreased the temperature rise of stator coils.In this paper,by studying the heat-fluid coupling temperature distribution of the bulb turbine generator,aims to using finite element method to obtain the internal temperature distribution of the bulb turbine generator and improve the research and development ability.The comparison between numerical calculation results and actual measurements shows that the heat-fluid coupling temperature distribution obtained by numerical calculation has certain accuracy and authenticity and is useful for the practical engineering application.