定子多风路空冷汽轮发电机流场模拟湍流模型验证与分析

Verification and analysis on turbulence model of flow field simulation for multiple ventilation stator ducts of air-cooled turbo generators

研究一种湍流模型模拟定子多风路大型空冷汽轮发电机中的具有多种流动形势转变特征的复杂流动。以一台三进四出定子多风路的空冷汽轮发电机为原型,建立了包括风扇、定子、转子、气隙在内的通风系统实验台,采用热线风速仪测量了1 000 r/min稳态工况下出风区中多个定子风沟出口截面的风速;然后,建立了实验台物理模型并采用三维建模软件进行了数学建模,在相同工况下进行数值计算,同时将测量结果与采用3种湍流模型得到的计算结果进行对比。结果表明:采用RNG k-ε模型时的风速计算结果与实验结果误差最小,RNG k-ε模型更适合模拟定子多风路的大型空冷汽轮发电机整机内部的流场。最后,分析了采用RNG k-ε湍流输运模型时实验台内部的流场分布特征。所得结论可为大型空冷汽轮发电机通风冷却设计提供理论参考。

A suitable turbulence model was researched for the simulation of the complex flow characteristics in multiple ventilation large air cooled turbo generator.A three inlets and four outlets of multiple ventilation stator ducts of turbo-generator with air coolant was comprised as the prototype,including fan,stator,rotor,air gap and ventilation system experimental bench.The values of wind speed of multiple stators duct outlet zone were measured under 1 000 r/min steady-state condition using the hot-wire anemometer.Then,physical model was established by using three-dimensional establishing software and was used for numerical calculation under the same condition.The measurement results are compared with the calculation results of standard k-ε,realizable k-εand the RNG k-εturbulence models.The results show that calculation of RNG k-εmodel has the minimum error with experimental results,which is more suitable for the simulation of the distribution of the flow field in a large air cooled turbo generator.Finally,experimental bench interior flow field distribution characteristics of RNG k-εmodel adopted were analyzed.The conclusions provides a theoretical reference for the design of ventilation cooling of Large Air-cooled Turbo generator.