Fuel Consumption at cruise conditions for hypersonic vehicles is one of the major criteria in the nozzle definition process Accurate estimation of the nozzle performances and the internal flow behavior are important. First step of the study consist in an evaluation of the geometrical design parameter influences on flow and thrust coefficients with 2D EULAR solver. Compatibility with requested thrust along the climb and the cruise, must be checked. 2D EULAR + boundary layer were carried out. Last step of the design process was supported by 3D EULAR and 3D NAVIER-STOKES. Mach 5 nozzle definition was tested in measurements and upstream total and static pressure screening. Comparison between predictions and test results validate the numerical design means. The numerical results will give helpful elements to get better understanding of phenomena in 2D nozzle.

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In this paper, the performance of vaned diffusers on low specific speed centrifugal compressors, was investigated experimentally and analytically. There is a problem of non-uniform distribution of the flow at impeller exit, as a factor to deteriorate the performance of the diffuser. This problem appears remarkably on the low specific speed type, because the blade height is relatively small and the flow inclines toward circumferential direction. The experiment was carried out with 2nd stage compressor of two-stage centrifugal type, focusing on the effect of number of diffuser vanes, vaneless ratio and throat area. Furthermore, unsteady fluid analysis was carried out by using Non Linear Harmonic method in order to understand about the phenomenon associated with the problem of non-uniform distribution of the flow.

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