Contour design of super/hypersonic dual-inflection nozzle

In order to achieve multi-Mach number run for the direct-connected test bench and high temperature wind tunnel,a straightforward technique has been developed to quickly determine a design of the super/hypersonic dual-inflection nozzle.The nozzle was divided into two sections to be designed,and the first was shared for different test Mach number.B-Spline functions were used to describe the Mach number distribution along the axial line of the nozzle.The preliminary nozzle contour was generated by a new computer program that solved the axisymmetric Euler equations using the method of characteristics.The final nozzle design was obtained by adding the boundary-layer thickness which was solved with the reference temperature method.An example of a dual-inflection supersonic nozzle design was employed to illustrate the technique with a computational fluid dynamics calculation.The simulation results indicate that desired Mach numbers are obtained at the nozzle exit,and the good flow quality is attained for different nozzles within Mach number error less than 1.2% in the test rhombus region.The present technique improves the design precision of the converging-diverging nozzle,cancels waves completely,and achieves the nozzles with different exiting Mach numbers which shares subsonic section and a portion of supersonic section.