EFFECT OF CUTOUTS ON UNDEREXPANDED RECTANGULAR JETS

The flowfield characteristics of jets from plain and rectangular orifi ces with semi-circular cut-outs have been experimentally investigated for both sonic and underexpanded conditions. Detailed pitot pressure m easurements revealed that the cut-outs had a strong influence on the e merging flowfield. The rectangular orifice with cut-outs at the minor axis ends showed more effective mixing with shorter core lengths and f aster near field jet decay when compared with the plain rectangular an d the rectangular orifice with cut-outs at the major axis ends. The ge neral trend of variation of shock cell length with fully expanded Mach number was consistent with Tam's theory, but the shock cell length of orifice jets were less than that predicted by Tam.