Turbulent mixing and concentration measurement

A laser Doppler velocimeter and a laser scatter system were used to measure flow velocity and tracer concentration. Tests were carried out on a turbulent air jet of circular cross section exhausting into still air. Effects of turbulence on the mass transfer characteristics of the flow were studied using laser equipment in combination with an oil smoke tracer. The laser Doppler velocimeter was used to make velocity field measurements and the laser scatter system provided the instantaneous mass fraction of smoke at the same point in the flow field. The flow field was examined at locations varying from 2 to 20 diameters downstream of the nozzle. Parameters recorded at each downstream station were: mean axial velocity, mean concentration, fluctuating velocity and concentration, and velocity concentration correlation.