不同形式喷管流动与红外抑制特性数值分析

Numerical Investigation of Flow and Infrared Suppressing Characteristics of Nozzles in Different Style

本文针对涡扇发动机,设计了等进口、出口面积,等长度的轴对称、矩形与S弯收敛喷管(出口宽高比W/H=4),在相同的内、外涵进口、出口参数下,数值分析了其流动、换热与红外辐射强度分布特性。比较得出,S弯喷管在矩形喷管基础上,进一步强化了二次流流动,增强了掺混,使得热喷流温度衰减增强;S弯壁面对进口高温部件形成有效遮挡,有效降低了红外辐射强度。水平探测面上,不同喷管红外辐射强度分布相似,S喷管量值最小,而在垂直探测面上,S弯喷管最大值出现高度角为20°时,这是由于尾喷流的向上偏转导致的。相比轴对称喷管,在喷管正后方,矩形喷管红外辐射强度降低23.1%,S弯喷管降低89.7%。

Three different types of convergent nozzles were designed. They used the same inlet, exit area, and length including the same symmetric axis. They were rectangular and S curved nozzles with an exit aspect ratio of W/H=4. The flow, heat transfer, and infrared suppressed characteristics were numerically investigated and analyzed. The secondary flow and mixing intensity were enhanced in the S curved nozzle which caused a faster decay of the hot plume. Meanwhile, the nozzle inlet and other hot components were shaded by an S curved wall. Due to the special construction, an asymmetric characteristic was observed in the vertical detecting plane and the maximum value of thermal radiation was 20° which was caused by the hot plume. Compared with an axisymmetric nozzle used for radiation intensity detected from behind, the rectangular nozzle reduced it by 23.1%. The S curved nozzle further lowered it by 89.7%.