The flow field characteristics of a two-dimensional uninhabited combat air vehicle (UCAV) aft-body integrated asymmetry-expansion nozzle in ground condition were simulated using a numerical approach which has been validated by NASA (National Aeronautics and Space Administration) experimental data.This study was conducted at NPR (nozzle pressure ratios) from 2.0 to 5.5.Results indicate:(1) In spite of nonuniform expansion at different transverse slices of the UAV (unmanned aerial vehicle) aft-body integrated nozzle

the maximum propulsive performance strongly lies on area ratio of upper shorter ramp end location to the throat. (2) The mixture of internal jet and external cold air can be enhanced by secondary flow and vortex

which are induced by the nonuniform expansion at different transverse slices of the UAV aft-body integrated nozzle. (3) As the NPR increases within this study

the propulsive performance of the nozzle varies a little.