Based on CFD technology

the effects of major geometric parameters on performance of the single expansion ramp nozzle were numerically investigated by solving Reynolds average Navier-Stokes equations and standard two-equation k-ε turbulent models.The results show that upper ramp length

upper ramp angle

lower flap length

lower flap angle have evident effects on flow field structure and the performance of SERN.With the increase of upper ramp length

the expansion in SERN transits from under-expansion to over-expansion

thus an optimal upper ramp length is found to create maximal thrust coefficient.The upper ramp angle

lower flap length

and lower flap angle also have optimal values for SERN performance.