【作者】 王可立；

【导师】 陈浮；

【作者基本信息】 哈尔滨工业大学 ， 动力机械及工程， 2006， 硕士

【摘要】 推重比15~20或更高推重比发动机关键技术之一是提高压缩系统级负荷或压比,为了使得负荷或压比的增加不会引起压气机级数的增加,就需要研制更高载荷的叶片,加大叶片对气流的折转能力,而这将必然直导致叶栅流道内三维分离的加剧,并引起二次流损失增加。因此,研究大折转角压气机叶栅中的流动状况和损失分布情况,探索改善栅内流动、降低叶栅损失的方法及其机理是非常必要的。本文实验在哈尔滨工业大学推进理论与技术研究所低速扇形叶栅风洞上进行,在四种不同正、负冲角条件下,采用五孔L型五孔探针及U型水排对60°叶型折转角下不同弯曲角度的叶栅进行了详细的测量,并对壁面做了墨迹流动显示分析。实验包括有直叶栅(STR)和15°(PB15)、20°(PB20)、25°(PB25)三正弯叶栅等4套叶栅,在四种冲角条件下共计16种方案。为了得到零冲角下叶栅内的流动情况,文中利用数值模拟方法对流道内的气动参数进行了分析。实验和计算的结果表明,具有大折转角压气机叶片的扇形叶栅中,流动具有很强的三维性。在直叶栅流道内,损失主要集中分布于两端壁附近与端壁/吸力面角区,角区内存在较为明显的回流。与直叶片相比,正弯叶栅的端壁损失显著减小,而中径附近损失有不同程度的增加。正弯叶片根部负荷减小而中部负荷增加,沿流向逆压梯度在根部较短而在中部较长,这使得正弯叶栅端壁/吸力面角区的回流和分离范围明显减小。所有的叶栅中,叶片吸力面都形成了沿叶展两端压力高中间压力低的“C”型静压分布,但正弯叶片更为明显。在零冲角下采用正弯15°叶片的叶栅损失最低,而25°正弯叶栅的损失要大于直叶栅。不同冲角下的实验结果表明大折转角的压气机变工况性能不好,最小损失对应的冲角减小。正弯叶栅在正冲角下的吸力面叶展中部分离严重,中部的损失激增,因而导致所有的正弯叶栅总损失明显的高于直叶栅。总的来说,25°大弯角正弯叶栅的变工况性能在四种叶栅中是最不理想的,而15°的表现出相对较好的变工况性能。更多还原

【Abstract】 High stage load or high stage pressure ratio of the compressor system is one of the most important facts for an aircraft engine with thrust-weight ratio of 15~20 or higher. To reach higher pressure ratios with fewer stages, development of a highly-loaded blade by which flow can be highly turned is necessary. However, this will lead to aggravation of separation and increment of secondary loss in the compressor cascade. It is of high value to study the inner flow structure and loss increase mechanism and explore the method of lowering loss inside high turning compressor cascades.In this paper, a detailed experimental investigation was carried out in a low speed, large scale wind tunnel with four different compressor cascades composed of conventional straight blades, positive curved blades with curved angle of 15°, 20°, and 25°respectively. At design and off-design conditions, the cascade flow fields were measured by five-hole probe detailed, the static pressure was measured by tapping on the cascade surfaces and ink-trace flow visualizations is also conducted. To get details of flow field inside the cascades at design condition, numerical simulation was carried out by the commercial CFD software——FLUENT. Experimental and computational result shows that flow in the high turning compressor cascade is highly tridimensional. In the flow passage of Straight cascade, loss concentrates near endwalls and in the endwall corner region. There is weak reverse flow in the corner. In the case of positive curved cascade, compared with straight cascade, the loss near endwall decreases while increases near midspan; the blade loading is reduced at the endwall and increased at the midspan; the length of axial reverse pressure gradient is shorter near endwall and longer at midspan. Both of the two configurations can eliminate reverse flow in the endwall corner region and reduce the corner flow separation region notably. Spanwise C-shape static pressure distribution was established on the suction surface of all blades, and it is more intensive in positive curved blades.At design condition, the lowest mass-weighted average total pressure loss appears in the positive curved cascade with curve angle of 15°, and the highest更多还原