Impact of boundary-layer separation on local exhaust design and worker exposure

Technical Report · Mon Jan 01 04:00:00 EST 1990

OSTI ID:5669120

George, D K; Flynn, M R; Goodman, R

Flow visualization and tracer gas studies were conducted in a wind tunnel with a mannequin, to examine the phenomenon of boundary layer separation as it relates to a worker's breathing zone concentration. A simple conceptual model was used which was based on mass transport by vortex shedding. The model provided a reasonable estimate of the mannequin breathing zone concentration. An empirical model was developed which then related the measured concentration to the distance from the source to the breathing zone for conditions where the contaminant was released downstream in a uniform flow. The results of the mannequin experiments suggested that boundary layer separation plays a significant part in determining the concentration of contaminant in the breathing zone. The interaction of the separated boundary layer with a contaminant source downstream of a person in uniform flow can pull contaminant back into the breathing zone of the person. The amount of contaminant observed in the breathing zone was much less when the mannequin was positioned such that the air could flow from the side. The turbulent mixing zone was formed more to the side of the mannequin and thus has less opportunity to interact with the contaminant source. These results suggested that in situations such as paint booths where a worker is immersed in a uniform flow, a higher level of control may be achieved by standing to the side of the workpiece.

• Research Organization: North Carolina Univ., Chapel Hill, NC (United States). Dept. of Environmental Sciences and Engineering
• OSTI ID: 5669120
• Report Number(s): PB-91-185298/XAB; CNN: PHS-OH-02392
• Country of Publication: United States
• Language: English

Related Subjects

560300* -- Chemicals Metabolism & Toxicology
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
AIR FLOW
AIR POLLUTION
AIR POLLUTION CONTROL
BOUNDARY LAYERS
COATINGS
CONTROL
DESIGN
ECOLOGICAL CONCENTRATION
ENVIRONMENTAL TRANSPORT
EXHAUST GASES
EXHAUST SYSTEMS
FLUID FLOW
FLUIDS
GAS FLOW
GASEOUS WASTES
GASES
INDOOR AIR POLLUTION
INHALATION
INTAKE
LAYERS
MASS TRANSFER
MATHEMATICAL MODELS
OCCUPATIONAL EXPOSURE
PAINTS
POLLUTION
POLLUTION CONTROL
SIMULATION
TUNNELS
UNDERGROUND FACILITIES
VENTILATION
WASTES
WIND TUNNELS