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The Impact of Boundary Layer Separation on Local Exhaust Design and Worker Exposure.

Authors
George-DK; Flynn-MR; Goodman-R
Source
Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina 1990 Feb:28 pages
Link
NIOSHTIC No.
00197938
Abstract
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. This 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.
Keywords
NIOSH-Grant; Control-technology; Air-flow; Air-quality-control; Air-sampling; Spraying-booths; Ventilation;
Contact
Environmental Sciences & Engr University of North Carolina Rosenau Hall 201H Chapel Hill, NC 27514
Publication Date
19900201
Document Type
Final Grant Report;
Funding Amount
113206.00
Funding Type
Grant;
Fiscal Year
1990
NTIS Accession No.
PB91-185298
NTIS Price
A03
Identifying No.
Grant-Number-R01-OH-02392
NIOSH Division
OEP
Priority Area
Control Technology and Personal Protective Equipment; Research Tools and Approaches; Control-technology;
Source Name
Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina
State
NC;
Performing Organization
University of North Carolina Chapel Hill, Chapel Hill, North Carolina
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