Measurements on an axisymmetric jet in a slow coflowing stream

All previously measured round turbulent jets are either contained in a recirculation region of are immersed in a coflowing stream which is too strong to obtain normal jet development. The purpose of this research is to include a slow, coflowing stream to avoid recirculation without greatly altering the development of the jet. The flow consists of a round water jet with Reynolds number, U sub j/nu d/ = 25000, submerged in a water tunnel with external stream velocity, U sub s = U sub j 150. The width of the duct is 64 times the nozzle diameter. This combination of duct size and velocity ratio results in no recirculation while the development of the jet resembles the development of a jet with no coflow. Velocity and concentration are surveyed in the jet by optical techniques. Velocity is measured by frequency-shifted laser Doppler velocimetry; concentration is measured by laser-induced fluorescence (of fluorescein sodium). Fluorescence intensity is also used to examine the concentration of reaction-product in an acidbase reaction between the jet and surrounding fluid. Requirements and applications of the fluorescence technique are also examined.