Buoyant Turbulent Jets and Flames. Part 3. Round Turbulent Nonbuoyant Starting Jets and Puffs and Buoyant Starting Plumes and Thermals. Annual Report.
Buoyant Turbulent Jets and Flames. Part 3. Round
Turbulent Nonbuoyant Starting Jets and Puffs and Buoyant
Starting Plumes and Thermals. Annual Report.
(1848 K)
Sangras, R.; Dai, Z.; Faeth, G. M.
GDL/GMF-99-03; 37 p. October 1999.
Sponsor:
National Institute of Standards and Technology,
Gaithersburg, MD
Keywords:
turbulent jets; turbulent flames; buoyant plumes;
buoyant flow; experiments; salt water
Abstract:
A theoretical and experimental study of the temporal
development of round turbulent nonbuoyant starting jets
and puffs and buoyant starting plumes and thermals is
described, limited to sources in still and unstratified
environments. The experiments involved dye-containing
salt or fresh water sources injected vertically downward
into fresh water within a large windowed tank with
injector passage length/diameter ratios of 50.
Time-resolved video images of the flows were obtained
using a CCD camera. Initial jet exit conditions were as
follows: diameters of 3.2-12.7 mm, Reynolds numbers of
1450-11700 and jet/ambient density ratios of 1.00-l.12.
Near-source behavior varied significantly with source
properties but the flows generally became turbulent near
the jet exit with self-preserving behavior generally
observed at distances greater than 20-30 source
diameters from the source. Within the self-preserving
region, both the normalized streamwise penetration
distance and the normalized maximum flow radius varied
as function of time to the following powers: l/2
(starting nonbuoyant jet), l/4 (nonbuoyant puff), 3/4
(starting buoyant plume), and l/2 (buoyant thermal).
