This paper reports an experimental investigation of bulk properties of
turbulent, which is three dimensional, incompressible, air jets issuing into
still air surrounding from the nozzles. The jet orifices utilized included
circular, hexagonal and cruciform geometries. Experimental results of
pertinent mean flow properties such as axis velocity decay, half width
growth, potential core and turbulence intensities are reported. Single
Hotwire anemometer was used for measurements of the velocity field. The
experiment for the three jets was conducted under the same nominal conditions
with the exit Reynolds number of 15,400. Consistent with previous
investigations of other non circular jets, the cruciform jet is found to have
an overall superior mixing capability over the circular counter part.
Immediately downstream of the nozzle exit, it entrains, and then mixes with,
the surroundings at a higher rate. This jet has a shorter potential core with
higher rates of decay and spread than the circular jet. This phenomenon of
axis switching is also found to occur in this jet.
Characteristic study of non-circular incompressible free jet