Buoyant Turbulent Jets and Flames. Part 1. Adiabatic Wall Plumes. Annual Report.
Buoyant Turbulent Jets and Flames. Part 1. Adiabatic
Wall Plumes. Annual Report.
Sangras, R.; Dai, Z.; Faeth, G. M.
GDL/GMF-99-01; 67 p. October 1999.
Sponsor:National Institute of Standards and Technology,
turbulent jets; turbulent flames; buoyant plumes;
An investigation of the structure and mixing properties
of buoyant turbulent plumes is described, motivated by
the need to resolve effects of buoyancy/turbulence
interactions and to provide data required to benchmark
models of buoyant turbulent flows for fire environments.
Flows considered in this part of the report include
plane adiabatic wall plumes; a second part of the report
will consider starting nonbuoyant and buoyant turbulent
jets and plumes. Measurements included laser-induced
fluorescence (LIF) to find mixture fraction statistics
and laser velocimetry (LV) to find velocity statistics,
emphasizing conditions far from the source where effects
of source disturbances and momentum have been lost. The
results show that earlier measurements in the literature
were not carried out far enough from the source to
provide self-preserving properties and that actual
self-preserving adiabatic wall plumes are narrower than
previously thought. Adiabatic wall plumes were also
found to mix much more slowly than free line plumes
because the presence of the wall inhibits access on one
side of the flow and the development of large turbulent
eddies that dominate the turbulent mixing processes in
these flows. This reduced rate of mixing of turbulent
wall plumes is a concern in fires because it extends the
length of the flame-containing region and reduces the
rates of dilution of the flow that is needed to reduce
temperatures and toxic gas concentrations in fire