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Empirical validation of theoretical velocity fields into flanged circular hoods.

Authors
Flynn-MR; Ellenbecker-MJ
Source
Am Ind Hyg Assoc J 1987 Apr; 48(4):380-389
NIOSHTIC No.
00165451
Abstract
Hot film anemometry was used to test theoretical models of the three dimensional velocity field into a flanged circular hood, both with and without a crossdraft perpendicular to the hood center line. Tests were carried out to measure velocities in front of representative flanged circular hoods with no crossdraft, and the predicted results of three models were compared with the measurements. Graphs of the velocity plotted on the ordinate and the corresponding theoretical quantity on the abscissa were used to evaluate the models. With minor empirical changes, one model yielded a straight line graph indicative of the line of exact agreement. The three dimensional velocity field for a flanged circular hood functioning without crossdrafts was defined mathematically according to that model using a simple microcomputer program. The introduction of the crossdraft perpendicular to the center line of the hood was found to add a series of well determined velocity components. Hot film anemometry validated empirically the theoretical findings in the plane parallel to the direction of the crossdraft, where the theoretical velocity vectors were two dimensional. The effects of crossdrafts on hood performance were illustrated by computer generated streamline maps which were used to develop hood capture efficiency predictive models. The authors conclude that such maps can be used to define areas of field that are under control of the hood so that contaminating processes may be located appropriately.
Keywords
NIOSH-Publication; NIOSH-Grant; Exhaust-hoods; Ventilation-equipment; Mathematical-models; Dust-velocity; Equipment-design; Industrial-equipment; Air-flow; Industrial-hygiene
CODEN
AIHAAP
Publication Date
19870401
Document Type
Journal Article
Funding Amount
32545.00
Funding Type
Grant
Fiscal Year
1987
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-R03-OH-02101
Issue of Publication
4
ISSN
0002-8894
Source Name
American Industrial Hygiene Association Journal
State
MA
Performing Organization
Environmental Sci & Physiology Harvard Sch of Public Health 665 Huntington Avenue Boston, Mass 02115
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