A wind tunnel study to design large, open-top chambers for whole-tree pollutant exposure experiments

Journal Article · Fri Dec 01 04:00:00 EST 1989 · Journal of the Air and Waste Management Association; (USA)

DOI:https://doi.org/10.1080/08940630.1989.10466648· OSTI ID:6943143

Baldocchi, D D; White, R ^[1]; Johnston, J W ^[2]

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1. National Oceanic and Atmospheric Administration's Air Resources Lab., Oak Ridge, TN (USA)
2. Oak Ridge National Lab., TN (USA)

A wind tunnel study was conducted to determine the optimal design features of a large, open-top chamber, as needed for pollution exposure studies on mature trees. An optimally-designed, open-top chamber must minimize the incursion of ambient air through its opening and maintain a uniform treatment concentration throughout the chamber. The design features of interest are the diameter and height of the chamber and the deflection angle and opening size of any frustum that may be mounted on top of a model chamber. The main design features of open-top chambers are the velocity of air exiting through the top and the relationship between the length scale of the turbulence and the diameter of the chamber opening. As exit velocities increase, the proportion of eddies with sufficient force to penetrate into the chamber decrease. Therefore, for equal volumetric air flows, smaller opening sizes increase the exit velocities and reduce the number and extent of ambient air incursions. Almost total exclusion of ambient air is achieved as the exit velocity of the air exceeds the magnitude of one standard deviation of the vertical wind velocity measured at the chamber top. The incursion of ambient air is also reduced when the diameter of the chamber opening is smaller than the characteristic length scale of the turbulence, a measure of mean eddy size.

• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6943143
• Journal Information: Journal of the Air and Waste Management Association; (USA), Journal Name: Journal of the Air and Waste Management Association; (USA) Vol. 39:12; ISSN JAWAE; ISSN 1047-3289
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540120* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
560300 -- Chemicals Metabolism & Toxicology
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
AIR POLLUTION
BIOLOGICAL EFFECTS
CANOPIES
DESIGN
EXPOSURE CHAMBERS
PLANTS
POLLUTION
SCALE MODELS
SENSITIVITY
SIMULATION
STRUCTURAL MODELS
TREES
TUNNELS
TURBULENCE
UNDERGROUND FACILITIES
WIND TUNNELS