Analysis Of Internal Heat Dissipation And Flow Field Of Fan Unit Engine Room Based On FLUENT

At present,the single capacity of wind turbine is increasing day by day.The heat dissipation of wind turbine is also increasing.The temperature control in nacelle has become the key factor of wind turbine to large capacity.The distribution law of the flow field in the nacelle can be obtained intuitively through the method of computational fluid dynamics(CFD).The formation of the dead angle and vortex region of the airflow inside the nacelle can be also avoided by the method.Thus,the research and development cycle is reduced effectively and the test cost is saved.The specific guidance is provided for the technicians to do the heat dissipation design and solve the actual heat dissipation problem.Based on the understanding of the heat transfer theory and the basic methods of computational fluid dynamics analysis,the simplified nacelle model is established by means of 3D modeling software.The numerical simulation software ANSYS FLUENT is used to establish the mathematical model.In this thesis,a series of theoretical analysis is carried out on the gas flow characteristics in the nacelle,and the practical improvement schemes are put forward.The main research contents are as follows:(1)Basic theoretical study of heat transfer and computational fluid dynamics.This paper defines that the internal heat dissipation of nacelle belongs to the scientific category of temperature control.The key point is that reasonable heat dissipation makes the internal temperature of nacelle not to be too high,so as to prevent alarm shutdown and even fire.Heat conduction,heat convection and heat radiation are discussed in nacelle.The working steps,solving process of computational fluid dynamics and FLUENT software are described.(2)Establishment of physical and mathematical models of wind turbine nacelle.The reasonable and necessary simplification of the nacelle is carried out.The three-dimensional simplified physical model of the nacelle and its main components are established by using SolidWorks software.Based on the basic equations of the internal flow field and the analysis of the turbulence model in the nacelle,the numerical simulation analysis of the flow field in the nacelle is determined by using the RNG k-? model.(3)Improvement scheme and simulation analysis of nacelle heat dissipation.Three representative sections of the nacelle without bottom opening are studied.The results show that the high temperature area is mainly distributed between gear box and generator.Therefore,a scheme for improving the structure of the nacelle is proposed and the improved scheme is simulated and analyzed.(4)Experimental analysis on the improvement scheme of nacelle heat dissipation.Based on the FLUENT numerical analysis and actual data of wind power plant,a comparative analysis of the temperature inside nacelle and cooling temperature of the gearbox was carried out between the improved and the unimproved nacelle structure.The correctness of the improved scheme is verified.