Experimental Simulation of a Vertical Round Jet Issuing into an Unsteady Cross-Flow

This paper investigates the discharge of a vertical round jet into an unsteady cross-flow that consists of a mean flow and a sinusoidally oscillating component. An experimental technique is devised to simulate the unsteady cross-flow situation in the laboratory. A vertical jet-pipe-nozzle assembly i...

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Published inJournal of hydraulic engineering (New York, N.Y.) Vol. 127; no. 5; pp. 369 - 379
Main Authors Lam, K. M, Xia, L. P
Format Journal Article
LanguageEnglish
Published Reston, VA American Society of Civil Engineers 01.05.2001
Subjects
Applied sciences
Buildings. Public works
Exact sciences and technology
Hydraulic constructions
TECHNICAL PAPERS
Oscillating flow
Water jet
Dye test
Model study
Hydrodynamics
Surface wave
Numerical simulation
Flow velocity
Hydrodynamic dispersion
Crossflow
Unsteady flow
Experimental study
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Summary:This paper investigates the discharge of a vertical round jet into an unsteady cross-flow that consists of a mean flow and a sinusoidally oscillating component. An experimental technique is devised to simulate the unsteady cross-flow situation in the laboratory. A vertical jet-pipe-nozzle assembly is physically oscillated backward and forward in the steady flow stream of a laboratory flume, and the flow patterns are viewed by an observer moving with the jet. Dispersion patterns of the dye-marked jet fluid are studied with a phase-locked analysis of digitized flow images. Oscillations in cross-flow velocity are found to organize the jet fluid into regular large-scale fluid patches, which, after time averaging, lead to a widened jet width and enhanced dilution. Experiments are also carried out on a vertical jet discharging into a current with surface waves, a situation that approximates to a genuine oscillating cross-flow with a nonzero mean velocity. The two sets of experimental observations are found to match with each other. The validity of the experimental simulation technique is further supported by a computational fluid dynamics study of the flow problem, in which it is possible to produce an idealized oscillating cross-flow situation. The numerical results agree well with the experimental observations.
Bibliography:ObjectType-Article-2
SourceType-Scholarly Journals-1
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ISSN:0733-9429
1943-7900
DOI:10.1061/(ASCE)0733-9429(2001)127:5(369)