Effects of geometric parameters on performance of single expansion ramp nozzles

Based on 3-D numerical calculations, validated by experiment data, the effects of geometric parameters on the internal performance of single expansion ramp nozzles(SERNs) were studied, revealing the performance parameters of models at different nozzle pressure ratio. The results show that as flap angle increases, discharge coefficient C_m decreases, and C_m of the upward angle is about 2% lower than that of the downward. On the condition of low nozzle pressure ratio(NPR), axial thrust ratio C_fx of the short ramp is smaller than that of the long ramp, including that C_fx of the shortest is about 85%. The larger throat aspect ratio obtains larger C_m, while C_fx varies with throat aspect ratio. Serrated trailing edge angle makes plume expanding better, and the flap serrated angle gets small resultant pitch thrust-vector angle δ_p, such as the small flap serrated angle, of which δ_p is 12°.