Analysis of partially mixed supersonic ejector

This article presents an analytical model of a supersonic/subsonic, constant-area ejector whose exit flow is not uniformly mixed. The primary and secondary streams, separated by the dividing streamline, are treated as quasi-one-dim ensional. The shear stress on the dividing streamline, the resulting heat transfer, and the wall stresses are applied artificially on the streams. Axisymmetric and two-dimensional configurations are considered. The model predicts that the axisymmetric ejector provides better thrust augmentation than the two-dimensional one, the latter suffering from higher skin-friction losses. Thrust increases with ejector length, but at a diminishing rate. For all configurations, thrust augmentation decreases with flight Mach number and becomes zero at a flight Mach number of about 0.7. Increasing the primary-to-secondary area ratio has a minimal effect on thrust. The results compare favorably with available experimental data on pressure distributions and mass-flow ratios. Nomenclature A = cross-sectional area a = speed of sound b = ejector radius (A/5) or half-height (two dimensional) cp = specific heat at constant pressure H = total enthalpy h = static enthalpy / = length scale, Eq. (11) M - Mach number Mc = cpnvective Mach number m = mass flux p = pressure q = heat transfer R = gas constant r = velocity ratio, U^/U^ $ = entropy flux 5- = entropy T = temperature U = velocity x = streamwise coordinate y = transverse coordinate y = specific-heat ratio A£7 = tfcol - t/oc* 6W = shear-layer vorticity thickness 77 = density ratio, IJL = viscosity p = density T = shear stress