Velocity and density measurements in supersonic high-temperature exhaust plumes

A two-dimensional laser Doppler velocimeter and a Rayleigh scattering system were used to measure the mean velocities, turbulence quantities, and mean density in a supersonic high-temperature exhaust plume with and without an annular base how The distributions of mean temperature and Mach number were inferred. For both cases, the potential core of the supersonic jet extends about 6 nozzle diameters, and the how remains supersonic until about 15 nozzle diameters, The mean axial velocity, turbulence kinetic energy, shear stress, and temperature become self-similar downstream of the flow, similarities of turbulence quantities develop slower than the mean velocity, whereas the temperature similarity Is established upstream of the velocity Near the nozzle base of the coaxial jets, one and a half recirculation zones are formed, which represents an extreme of the central-jet-dominated coaxial flows.