An experimental study of supersonic mixer nozzles in a coflowing stream has been conducted in the UnitedTechnologies Research Center open jet acoustic wind tunnel. Enhanced supersonic jet mixing is important in a number of applications including jet exhaust noise reduction and improved flow distribution within engine combustors. Recently discovered novel concepts promoting enhanced mixing via the introduction of axial vorticity into the exhaust have resulted in studies of the mixing process for nozzles operating at low, subsonic Mach number conditions and low temperatures. The goal of the present experimental study was to evaluate these approaches to jet mixing in the high-temperature, supersonic primary flow regime typical of turbofan/turbojet engine operation. Jet total temperature, total pressure, static pressure, and velocity distributions were measured to characterize the mixing process for baseline slot and circular nozzles, and for several mixer nozzles. The measurements were made at a jet exit Mach number of 1.5, a wind-tunnel forward flight Mach number of 0.5, and a jet total temperature of 1000°F. A principal conclusion of this study is that the axial vorticity mixing mechanism previously shown to be responsible for rapid mixing in low-speed, subsonic flows is also effective in a supersonic flow environment. Reductions in nozzle potential core length of approximately a factor of two relative to the slot nozzle configuration were observed for one of the mixer nozzles studied.
Nomenclature= two-dimensional nozzle width (long dimension, in.) */ eq = diameter of equivalent area circular nozzle, in. dj = circular nozzle exit diameter, in. h = nozzle exit height (short dimension, in.) M 0 = tunnel freestream Mach number MJ = nozzle exit Mach number N T =jet center line total temperature decay exponent N u =jet center line velocity decay exponent P T = total pressure, psia PT O = tunnel freestream total pressure, psia P Tp , P T . = nozzle primary supply total pressure, psia Pr J = Prandtl number R = radial distance, in. T a > T To = tunnel freestream total temperature, °F T T ° = total temperature, °F TT P > T T = nozzle primary supply total temperature, °F U -velocity, ft/s x = axial coordinate, in. y = transverse coordinate, in. z = vertical coordinate, in.
