为深入探讨表面粗糙度对气膜冷却性能的影响及其机理，本研究提出了一种随机粗糙度生成方法，并利用低速风洞试验与数值模拟相结合的手段，获得了后倾扇形孔下游光滑面与粗糙面上的冷却效率云图分布及流场数据。试验中主流速度设定为20 m/s，吹风比分别为1.0、2.0与3.0。结果表明吹风比越大，增大粗糙度对主流区域的对涡结构影响越小，在所有工况下增大粗糙度都显著提高了壁面附近的速度波动，同时诱发了数量较多的旋涡，进而增强了冷气与主流的掺混过程。表面粗糙度对孔下游无量纲温度分布特征的影响在吹风比较小时较为显著，且粗糙度的影响沿流向逐渐增强。在低吹风比时，粗糙度增强了冷气的耗散，导致冷却效率降低约15%，而在高吹风比时，粗糙度引起的冷气扩散效应占据主导，使冷却效率提高约20%。

To investigate the influence of surface roughness on film cooling performance and the mechanisms， this study proposes a method for generating random roughness. By utilizing low-speed wind tunnel experiments and numerical simulations， the film cooling effectiveness distribution and flow field data of downstream of the laidback fan-shaped hole in the cases of smooth and rough surfaces were obtained. The mainstream velocity was set at 20 m/s， and the blowing ratio was 1.0， 2.0， and 3.0. Results indicate that as the blowing ratio increased， the impact of roughness on the counter-rotating vortex pair in the mainstream region decreased. In all the cases， increased roughness significantly enhanced the velocity fluctuations near the wall and induced numerous vortices， thereby intensifying the mixing process between the coolant and mainstream. The influence of surface roughness on the dimensionless temperature distribution characteristics downstream of the hole was more pronounced at lower blowing ratios， and the influence of roughness gradually increased along the flow direction. At low blowing ratios， increased roughness enhanced coolant dissipation， and reduced film cooing effectiveness by approximately 15%. However， at high blowing ratios， the diffusion effect of coolant caused by roughness played a major role， thereby increasing the film cooing effectiveness by about 20%.