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为进一步改善燃气轮机叶片前缘区域气膜冷却效果,在全尺寸燃气轮机透平级上对“直角孔”和“倾角孔”两种孔结构的流动和传热进行了数值模拟研究。结果显示“倾角孔”结构能够有效地提高前缘区域的冷却效率,在特定的结构参数下,其冷却效率最高可达直角孔的2.42倍。通过流场的分析对其提高冷却效率的机理进行了说明:倾角孔形成的气膜可以有效覆盖孔间和孔排间的冷却盲区,从而提高了冷却效率。此外还研究了吹风比、孔径和孔距对“倾角孔”冷却效率的影响。结果表明:倾角孔的冷却效率同时受到交错流有效度和和二次流与主流掺混度的影响,在这两个因素共同作用下,冷却效率存在着一个峰值;孔径的增大和孔距的减小可以提高冷却效率,但是由于孔排间二次流的干涉作用,孔距过小会导致冷却效率分布不均匀。
In order to further improve the film cooling effect in the leading edge of the gas turbine blade, the numerical simulation of the flow and heat transfer at the full-size turbine gas turbine was carried out. The results show that the “dip hole” structure can effectively improve the cooling efficiency of the leading edge region, and its cooling efficiency can reach 2.42 times of the rectangular hole under certain structural parameters. The mechanism of improving the cooling efficiency is illustrated through the analysis of the flow field: the gas film formed by the inclined holes can effectively cover the cooling blind spots between the holes and the rows of holes, thereby improving the cooling efficiency. In addition, the effects of blowing ratio, aperture and hole pitch on cooling efficiency of “dip hole” were also studied. The results show that the cooling efficiency of inclined holes is affected by both the efficiency of cross flow and the mixing degree with secondary flow and main flow. Under the combined action of these two factors, there is a peak in cooling efficiency; the increase of pore size and the pitch The decrease can improve the cooling efficiency, but due to the interference of the secondary flow between the rows of holes, the small hole spacing will lead to uneven cooling efficiency distribution.