Numerical Simulation Study On Thermal-fluid Coupled Field Of Rotor And Air-gap For 220MW Air-cooling Turbo-generator

The safety of power generating equipment will be deeply affected by the excessive local temperature rise when the turbo-generator is running. Therefore, in the design of turbo-generator, to accurately calculate the temperature rise of the various components can ensure the running safety of turbo-generator, improve cooling efficiency and facilitate the increase of the air-cooled turbo-generator capacity. The stator and the rotor were always calculated separately in the past numerical calculation which neglected the effect of air-gap. The air-gap rotating computational domain was established in this paper to make the computational modeling more practical and accurate.In this paper, the rotor and air-gap of 220MW air-cooled turbo-generator of Harbin Electrical Machinery Plant are taken as an example. In order to study the cooling-air flow, heat transfer characteristics in the rotor duct and air-gap and temperature distribution of the various components, the flow field and temperature field of rotor and air-gap was calculated by using the Finite Volume Method (FVM) based on the principle of Computational Fluid Dynamics (CFD).First, select the No. 8 slot winding duct as the research object which is the longest end wind path; establish the 3D flow field computation module for this slot of half axis length. Calculate the relative static pressure, relative wind speed and air flow distribution inside the duct of arbitrary regions under the steady state when the rotor is running at a speed of 3000r / min, then analyze the effects of factors on various physical quantities. Secondly, establish the complete 3D temperature field model for No. 8 slot of half axis length based on the flow field calculation. Calculate the temperature distribution in the various components of the rotor, then study the effect of different forms of sub-slot on the temperature distribution. Analyze the effect of different air-inlet arrangements at rotor end on air flow and temperature distribution inside the rotor. Finally, establish the 2-D annular model of air-gap to obtain the flow field and the temperature field in the air-gap. Then analyze the air flow features and heat transfer characteristics and research the factors of flow and heat transfer inside air-gap.In order to ensure the accuracy of numerical calculation, the numerical simulation results were compared with the experimental data of manufacturers. Then change a part of the duct structure based on the original structure to analyze its effects on the flow field and temperature field of the rotor and air-gap region. Explore the heat transfer mechanism of the rotor later.