旋转状态气膜冷却的大涡模拟

用大涡模拟的方法考察了静止和旋转状态下有直径4mm,35°流向倾斜圆柱孔的平板上气膜冷却的流动和换热,将静止状态预测的速度型与实验数据进行对比验证了计算结果的合理性.在固定吹风比为0.5、冷气进口雷诺数为2 588的情况下,静止和旋转状态的涡量分布出现明显差异,且旋转状态射流与主流相互作用的剪切层沿展向偏离气膜孔的几何中心线,使得原有对转涡对不再关于孔中心线对称分布,漩涡识别技术也发现典型的涡结构受旋转影响发生形态和运动规律的改变,进而影响湍流结构对主流和冷气掺混的作用.

Large eddy simulation of film cooling under rotating condition

Large eddy simulation was used to predict flow and heat transfer of film cooling on a flat plate perforated by 35° streamwise inclined cylindrical hole of 4mm under stationary and rotation conditions. The predicted non dimensional velocity profiles compared well with available experimental data in stationary case, justifying present simulations. But the discrepancy of temperature predicted by present work and that in reference numerical work was obvious. After introducing system rotation at the same blowing ratio and Reynolds number, vorticity distributions showed increasing distinctness along with the increased angular velocity. And the trajectory of shear layer between mainflow and coolant deviated towards spanwise under rotation condition, leading to the asymmetry of the counter rotating vortex pair after coolant injection. Furthermore, the dynamics of coherent structures detected in three cases also demonstrate the rotation effect, which significantly influences the mixing of mainflow and coolant and the consequential heat transfer.