球面收敛二元喷管出口三角形锯齿对气动和红外特性的影响

通过数值计算研究，分析了喷管出口锯齿修型对涡扇发动机排气系统球面收敛二元喷管气动及红外特性的影响.结果表明:相对于基准喷管，喷口锯齿修型均造成排气系统推力系数和总压恢复系数的下降，且齿底角越大，推力系数的损失越大.比较而言，内缩型锯齿修型方式对排气系统气动性能的影响最小，但导致排气喷流和总体红外辐射强度在±15°探测角附近的较大增强；外伸型锯齿修型对排气系统气动性能的影响最大；30°齿底角的等面型锯齿修型综合性能较优，对推力系数和总压恢复系数的影响微弱，同时在-30°~0°,0°~30°的探测视角内体现出一定的红外辐射抑制作用. 

Influence of outlet delta-chevrons on aerodynamic and infrared characteristics of spherical convergent two-dimensional nozzle

Numerical investigation was performed to study the influence of outlet delta-chevrons on the aerodynamic and infrared characteristics of a spherical convergent two-dimensional nozzle in turbofan engine exhaust system. Results showed that the trust coefficient and total pressure recovery coefficient decreased by the outlet shaped-chevrons in relative to the baseline nozzle, especially for the larger base angle of delta-chevron. By comparison, the inner-recessed-chevron mode had a least influence on the aerodynamic performance of exhaust system. However, it resulted in an obvious enhancement both for the exhaust plume and total infrared radiation at the detective angle in the vicinity of ±15°. The outer-extended-chevron mode had a most influence on the aerodynamic performance of exhaust system. The equal-area-chevron mode with a base angle of 30° seemed to be advantageous, as it had a weak influence on the trust coefficient and total pressure recovery coefficient, and also showed certain infrared radiation suppression in the detective angles of -30°-0° and 0°-30°.