Based on an non-oscillatory and non-free parameters dissipation difference (NND) scheme to solve three-dimensional Reynolds averaged Navier-Stokes equations

performance calculations and analysis of multi-module aerospike nozzles with round to rectangle inner nozzles were investigated. Flow characteristics and performance of four inner nozzles including bell nozzle

two-dimensional nozzle

round to square inner nozzle and square throat to square exit nozzle were compared. Then performance of round to rectangle inner nozzles that have different structures such as contour changing points

contours after changing points and exit arc radiuses were discussed. The effects of different structures of inner nozzles

different nozzle obliquities and different plug contours on the multi-module linear aerospike nozzles were also presented. And a design scheme of the optimized aerospike nozzle was given. Conclusions can provide some reference for studying design of the multi-module linear aerospike nozzles with round to rectangle inner nozzles.