MIXER-EJECTOR NOISE-SUPPRESSOR MODEL

A flexible and efficient compressible mixer-ejector model is described . This model is used to predict the performance of ejectors employing lobed mixers. Through comparisons with experimental data, the model is shown to qualitatively capture the impact of streamwise vorticity on the evolution of the mixing layer and to quantitatively predict the ch ange in the pressure coefficient through the duct associated with the mixing process to within 15%, The relative accuracy, speed, and flexib ility of the model make it useful as a preliminary design tool. Two de sign trade studies are performed with the model, First, the model is u sed to assess the impact of streamwise vorticity on the thrust and pum ping performance of a supersonic-subsonic mixer-ejector; for the mixer geometry utilized in this study, pumping and thrust augmentations are associated with the addition of streamwise vorticity. Second, the imp act of mixer height on the effectiveness of streamwise vorticity is ev aluated. The results of this study demonstrate that the effectiveness of streamwise vorticity decreases with increasing lobe height-to-wavel ength ratio, and for the higher height-to-wavelength ratios investigat ed, a net performance penalty is associated with the addition of strea mwise vorticity.