Fluid dynamic study of open-topped greenhouse. Final report, September 1, 1978-May 31, 1981

Technical Report · Thu Jan 01 04:00:00 EST 1981

OSTI ID:5216626

Thompson, C R

Fluid dynamics of air movements into and around open topped greenhouses were studied by two methods. A 1/12 scale model of a widely used greenhouse was tested in a wind tunnel and full scale testing was done in an open field. The wind tunnel studies simulated outside surface turbulent flow by placing rakes upstream from the test model to shed vortices. The air flows were visualized by emitting smoke upstream and photographing flow patterns with a high speed camera. In a second approach, CO at 250 ppM was injected into the bottom of the test model and the degree of dilution with CO free air was measured at various heights within the model. This series of studies showed near complete dilution of the model atmosphere with outside air and were so different quantitatively from previous results the approach was abandoned and full scale chamber studies were conducted. Carbon monoxide was injected into the incoming air stream. Measurements of CO at each point were made for two minutes each and concentration in the incoming duct which required 26 minutes. Windspeed and direction were measured simultaneously and correlations of wind-speed and exclusion of air were made with several chamber modifications. These latter studies show that: total exclusion of ambient air in open top structures is impossible; increasing windspeed especially above 15 mph cause extensive mixing at plant height, i.e., 0.5 M; extending the vertical height, installing a 45/sup 0/ deflector, or placing horizontal strips over the chamber top give only marginal improvement in ambient air exclusion; either a truncated cone or a flat plate with an open area of 40% give good exclusion of ambient air; and vertical ribbons or slats extending 0.67 m above the chamber wall which are 5 cm wide with 5 cm spacing was the most effective design for obtaining the desired exclusion and one which maintained the open top configuration.

• Research Organization: California Univ., Riverside (USA). Statewide Air Pollution Research Center
• DOE Contract Number: AT03-76EV70287
• OSTI ID: 5216626
• Report Number(s): DOE/EV/70287-T1; ON: DE82018423
• Country of Publication: United States
• Language: English

Related Subjects

500200* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
553000 -- Agriculture & Food Technology
560303 -- Chemicals Metabolism & Toxicology-- Plants-- (-1987)
60 APPLIED LIFE SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
AIR
AIR POLLUTION CONTROL
BUILDINGS
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
CONTROL
DESIGN
FLUID FLOW
FLUIDS
GASES
GREENHOUSES
ISOTOPE APPLICATIONS
OXIDES
OXYGEN COMPOUNDS
POLLUTION CONTROL
SIMULATION
SURFACE AIR
TRACER TECHNIQUES
TUNNELS
TURBULENT FLOW
UNDERGROUND FACILITIES
WIND TUNNELS