Generic Centerline Velocity Decay Curve for Initially Turbulent Axisymmetric Jets.
Generic Centerline Velocity Decay Curve for Initially
Turbulent Axisymmetric Jets.
(724 K)
Papadopoulos, G.; Pitts, W. M.
Journal of Fluid Engineering, Vol. 121, 80-85, March
1999.
Keywords:
turbulent jets; velocity measurement; flow measurement;
jets; turbulence; turbulent flow
Abstract:
Recently the authors introduced a length scale which
effectively collapsed the near field centerline
development of velocity and mass fraction for variable
density axisymmetric jets whose initial conditions
correspond to those of fully developed turbulent pipe
flow. The new length scale incorporated the initial
mass, momentum, and turbulence intensity per unit area
to capture the Reynolds number dependence of near field
development for the velocity and scalar distributions
observed in low Reynolds number turbulent jets. The
present paper extends the analysis for a constant
density jet to the intermediate and self-similar far
fields further downstream using a dynamic length scale
based on the local centerline turbulence intensity. The
normalized mean velocity distributions of an air jet
collapse over the entire flaw distance investigated when
the axial distance is normalized by the proposed length
scale, thus scaling the virtual origin shtft and
effectively incorporating the Reynolds number
dependence.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899