冷却孔非均匀排布波纹板隔热屏冷却特性仿真

为了更加合理地分配冷却气体流量，提高纵向波纹板隔热屏结构的气膜冷却效率，提出了非均匀孔排布局波纹板隔热 屏结构，即保持开孔率不变，构建了上游波纹结构气膜孔排布密集、下游波纹结构气膜孔排布稀疏的非均匀结构。在发动机真实 工况下，采用数值仿真的方法研究了非均匀孔排方式对沿程冷却气体流量分配特性和气膜冷却特性的影响规律，揭示了振幅比变 化对波纹板隔热屏冷却效果的影响规律。结果表明：前密后疏型非均匀孔排布局可以改变冷却气体在隔热屏不同位置处的出流 量，从而显著提高隔热屏的气膜冷却效率。在气膜孔孔参数以及开孔率不变时，增大隔热屏上游孔排密度既可以提高隔热屏上游 的冷却效果，又不会明显降低隔热屏下游的冷却效果，使隔热屏整体面平均气膜冷却效率有所提高，相比于均匀孔排结构，前密后 疏孔排布局最高可使隔热屏面平均气膜冷却效率提高12.66%；在相同工况下，当振幅比从0.035增大至0.075时，隔热屏的面平均 气膜冷却效率显著提高，最高可使其面平均气膜冷却效率提高16.32%。

Simulation of Cooling Characteristics of Corrugated Heat Shield with Non-uniformly Disposed Cooling Holes

In order to distribute cooling gas flow more rationally and improve the film cooling effectiveness, a corrugated heat shield structure with non-uniformly disposed cooling holes was proposed, which maintains the same open area and constructs patterns with high row-density cooling holes at upstream position and low row-density cooling holes at downstream position. Under real engine operating con- ditions, numerical simulations of the non-uniform cooling structures were carried out to obtain the characteristics of the cooling gas flow dis- tribution and the film cooling effectiveness along the flow path, and the influence of the amplitude ratio on film cooling effectiveness was also obtained. The results show that the cooling gas flow at different positions of the heat shield are changed by the non-uniform layout, thereby significantly increasing the film cooling effectiveness of the heat shield. While keeping the parameters of the film cooling hole and the open area unchanged, increasing the row density of the cooling holes at the upstream position can not only improve the cooling effectiveness of the upstream section but also keep the reduction in cooling effectiveness of the downstream section acceptable. Compared with the uniform lay- out, the maximum increase in area-averaged film cooling effectiveness is 12.66%. Under the same conditions, as the amplitude ratio increas- es from 0.035 to 0.075, the area-averaged film cooling effectiveness is significantly increased, with the highest increase of 16.32%.