STUDY OF DOUBLE CONCENTRIC JETS WITH DIFFERENT GEOMETRIC CONFIGURATIONS

The flow field of two different geometric configurations of a double concentric jet has been studied. This jet consisted of a round central jet emerging from a circular nozzle and an annular jet emerging from an annular nozzle which encircled the former. In the basic configuration, the annular jet issued parallel to the circular jet. In the other configuration, which is called the inclined configuration, the annular jet issued at an inclining 15-degrees to the circular jet. Hot wire anemometers were used to study the structure of the combined flow. The measured quantities included mean velocity, and longitudinal and lateral turbulence intensities. It was found that the combined flow of both the central and the annular jets can be simulated by the flow of an equivalent single round jet. The study indicated that the inclined jet developed at a faster rate than the basic jet. The mean velocity profiles of the basic jet showed a good agreement with a typical single round jet. Some agreement with a single jet was observed for the longitudinal turbulence intensity profiles of the inclined jet. Study of the lateral turbulence intensity profiles of both jet configurations showed poor agreement with those of a single jet. No agreement was found between the turbulent kinetic energy profiles and those for a single jet.