Environmental Fate of Toxic Chemicals on Surface Materials in Laboratory Wind Tunnels: Measured and Computed Wind Speeds and Flow Fields
Abstract
An understanding of the fate and effects of chemical agents on material surfaces under environmental conditions is becoming critical as the probability of contamination increases for military and civilian airports and seaports and Homeland targets. The methodology is not available for measuring the fundamental evaporation, desorption, and decomposition of chemical agents as a function of time in a controlled laboratory wind tunnel. The methodologies under development can be classified by the instrumental approaches as based on microbalances, vapor analysis, photo-imaging of droplet contact angle cross-sections, or combined methods. All approaches have a common requirement for well-characterized flow fields for the droplet in the laboratory wind tunnel geometry. The microbalance methodology described will be based on horizontal balances in a conventional mode, horizontal balance in the reverse flow mode for higher wind speeds, a vertical microbalance in evolved-gas, quasi-horizontal mode, and dual a beam differential thermal instrument mode. Two parallel approaches are being pursued to characterize the aerodynamic behavior in laboratory wind tunnels. Direct measurements are being performed of wind speed as a function of position relative to the agent droplet on the surface. Hot wire anemometry and micro-positioning devices are being employed for the measurements. Special calibration techniques were applied to extend the anemometer measurements to low wind speeds. Computational Fluid Dynamic (CFD) methods are being applied to the microbalance and vapor sampling wind tunnel geometries to complement the measured wind speeds and profile shapes.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 2003
- Accession Number
- ADA484073
Entities
People
- Daniel Weber
- John Molnar
- Wendel Shuely
Organizations
- Edgewood Chemical Biological Center