加力隔热屏及中心锥冷却对二元收扩排气系统红外抑制效果数值分析

Numerical Analysis of Infrared Suppression Effect of Afterburner Heat Shield and Cone Cooling on Two- Dimensional Convergent-Divergent Exhaust System

关键词:  涡扇发动机  二元排气系统  气膜冷却  加力隔热屏冷却  中心锥冷却  红外抑制

Key words:  Turbofan engine  Two-dimensional exhaust system  Film cooling  Afterburner heat shield cooling  Cone cooling  Infrared suppression

摘要:

针对涡扇发动机二元收扩（2D C-D）排气系统，数值探究了加力隔热屏与中心锥气膜冷却对热部件温度的影响，并揭示了冷却措施对排气系统的红外抑制作用以及随之引起的推力系数变化。结果表明：对加力隔热屏开气膜孔可有效降低隔热屏温度，其峰值最大降低10.3%，且加力隔热屏结构、气膜孔倾角不同均会影响内外涵流量分配；加力隔热屏气膜冷却主要抑制30°~75°的红外辐射，辐射强度可降低8%~25%，但同时推力系数最高降低5.3×10^-3。对加力隔热屏与中心锥采取联合气膜冷却后，中心锥表面温度明显降低，0°~10°的红外抑制作用效果显著，辐射强度降幅最高达31.3%，随之引起的推力系数损失不超过3.0×10^-3。

Abstract:

Aiming at the turbofan engine with a two-dimensional convergent-divergent （2D C-D） nozzle exhaust system， the effects of the afterburner heat shield and cone film cooling on the temperature of components were investigated numerically， and the infrared suppression of the cooling measures on the exhaust system and the consequent changes in thrust coefficient was revealed. The results show that the surface temperature of the heat shield can be effectively reduced by film cooling of the afterburner heat shield，and the maximum peak reduction is 10.3%，and the structure of the afterburner heat shield and the different inclination of the film holes affect the core and bypass flow distribution.Film cooling of the afterburner heat shield mainly suppresses infrared radiation （IR） from 30°~75°， and the radiation intensity can be reduced by 8%~25%， but at the same time， the thrust coefficient is reduced by up to 5.3×10^-3.After film cooling is taken for the afterburner heat shield and the cone，the surface temperature of the cone is obviously reduced， and the infrared suppression from 0°~10° is significant， its radiation intensity decreases by up to 31.3%，the consequent loss of thrust coefficient does not exceed 3.0×10^-3.