Scaling the Near-Field Centerline Mixing Behavior of Axisymmetric Turbulent Jets.
Scaling the Near-Field Centerline Mixing Behavior of
Axisymmetric Turbulent Jets.
(1012 K)
Papadopoulos, G.; Pitts, W. M.
AIAA Journal, Vol. 36, No. 9, 1635-1642, September
1998.
Keywords:
turbulent jets; density effects; flow measurement;
Rayleigh light scattering; turbulence; turbulent flow
Abstract:
Detailed measurements of the centerline mixing behavior
in the near field of varible-density jets were
performed. Real-time measurements of jet fluid
concentration for a propane jet and a methane jet
issuing into still air were made utilizing Rayleigh
light scattering. The initial conditions were those of
fully developed pipe flow, and testing was done for flow
rates yeilding Reynolds numbers in the range of 3.3 x
103-2.3 x 104, based on the average discharge velocity,
exit diameter, and initial fluid properties. Centerline
decay characteristics in the near field exhibited a
downstream shift with increasing Reynolds number, which
was attributed to the initial velocity distribution at
the jet exit. Investigation of the mean and turbulent
characteristics of the initial velocity distribution
yielded a proposed near-field scale variable that
effectively captured this dependence on Reynolds
nyumber. Collapse of the near-field centerline velocity
and concentrations distributions was achieved using the
proposed scaling.
