Abstract: Based on computational fluid dynamics/ infrared radiation (CFD/IR) numerical simulation method, this article reveals the influence of different structures on the pneumatic and infrared radiation characteristics of a single expansion ramp nozzle (SERN), including gaps on the ramp, angle of the ramp and area ratio of the nozzle. The results show that infrared radiation intensity is decreased obviously and the pneumatic performance is also improved when a series of gaps are made on the ramp. The peak value of plume infrared radiation intensity is decreased by 25.2% at the coordinates of the yOz plane and 26.4% at the coordinates of the xOz plane, and the average temperature of the ramp is decreased from 643 K to about 335 K. With the increase of the ramp angle, the thrust-vector angle is enlarged and the axial thrust ratio is decreased, and the shelter effect of the ramp on the inner-wall and plume is weakened. With an increase of the area ratio, the infrared radiation intensity is decreased, while at the same time the thrust of the SERN is also decreased.

Key words: single expansion ramp nozzle, wall cooling, pneumatic performance, infrared radiation, numerical simulation