缩放型冷却孔结构参数对燃气轮机动叶气膜冷却效果的影响研究

Influence of Structural Parameters of Convergent-divergent Shaped Holes on the Film Cooling Effectiveness of a Gas Turbine Moving Blade

为了增强燃气轮机动叶的气膜冷却效果,提出一种缩放型气膜孔结构,采用数值模拟的研究方法,模拟了吹风比M?1.0、主流湍流度Tu?5%时,分别带有扩张角度??0?、??5?、??10?和??15?的4种缩放型冷却孔叶片的气膜冷却效果,并用平均气膜冷却效率和不均匀系数两个新型评价指标辅以评价叶片冷却效果。研究结果表明:缩放孔型的扩张角度由??0?增加至??10?的过程中,无论是在叶片压力面还是吸力面上,气膜冷却效率整体呈递增趋势,其纵向平均气膜冷却效率和横向平均气膜冷却效率逐渐增大,不均匀系数降低,冷却效果增强。当扩张角度增大至??15?时,相对于带有??10?孔型的叶片,其压力面和吸力面上的气膜冷却效率出现下降,纵向平均气膜冷却效率和横向平均气膜冷却效率减小,不均匀系数增大,冷却效果变差;在带有不同孔型的叶片的中后缘位置都出现了明显的高冷却区域,带有扩张角度??10?孔型的叶片在该区域的冷却优势更明显;4种孔型在叶片吸力面上气膜覆盖的整体均匀度都要比压力面高。

In order to improve the air film cooling effect of moving blades in gas turbine, a convergent-divergent shaped air film hole structure was put forward. The method of numerical simulation was applied to analyze the film cooling effect of convergent-divergent shaped holes on the blade. The convergent-divergent shaped holes with such expansion angle as α=0°,α=5°,α=10° andα=15° were simulated when blowing ratio M=1.0 and mainstream turbulence degree Tu-5%.Such two new kinds of evaluation indicators as average film cooling efficiency and cooling non-uniformity coefficient were used to evaluate the film cooling efficiency. The research results show that when the expansion angle increases from α=0°to α=10°, the air film cooling effectiveness increases on both the blade pressure surface and suction surface,and the longitudinal and transverse average film cooling efficiency increase gradually, and the cooling non-uniformity coefficient decrease, and the effect of film cooling is enhanced.When the expansion angle increases from α=10? to α=15?, the air film cooling effect decreases, and the longitudinal and transverse average film cooling efficiency decrease gradually,the cooling non-uniformity coefficient increases, and the cooling effect becomes worse. In the middle and tail regions of the blade with different convergent-divergent shaped holes,obvious high cooling efficiency area has appeared, the advantage of blades with expansion angle ??10? is more obvious. Film coverage uniformity on the suction surface is better than that on the pressure surface.