旋转带肋U型通道内流动与换热的数值模拟

Simulation of turbulent flow and heat transfer in a rotating ribbed serpentine passage

关键词:  燃气涡轮机  冷却叶片  对流传热  旋转

Key words:  Gas turbine  Cooled blade  Convective heat transfer  Gyration

摘要:

为了获得能够模拟高参数涡轮叶片内冷通道换热效果的模型,数值模拟了旋转状态下U型通道内的流场和温度场,比较了数值模拟与实验的结果。结果表明:所采用的计算程序和模型与实验结果吻合。旋转状态下,通道内各面换热的变化是和通道内流场的变化密切相关的;哥氏力在垂直于旋转半径截面上的不均匀分布引起流动较大变化,对通道内各面换热的影响比较大。哥氏力的作用较大幅度强化指向面换热,小幅强化两侧面换热,而弱化背向面换热。对于带肋通道,总体上阻力系数随着旋转速度的增加而升高。

Abstract:

A two-equation turbulence model with additional term for Coriolis and buoyancy was used to study turbulent flow and heat transfer in a rotating ribbed serpentine passage. Using air as the coolant, operating conditions were selected to match the test model operating parameters. The simulation results are almost consistent with the experimental data. The results indicated that the unbalance distribution of Coroilis force plays an important role in flow and heat transfer in rotational passage. Two new flow structures caused by Coroilis force were found: (1) Axial velocity profile is outward along Coroilis force direction; (2) Secondary flow appears on the section perpendicular to the main flow. These two phenomena enforce the heat transfer on the face the Coroilis force point to and both the side faces. The heat transfer on opposite face is weakened at lower rotating speed and recovers with the rotating arisen. Coroilis force increases pressure loss in the ribbed passage while centrifugal buoyancy force decreases pressure loss.