Wind Tunnel Evaluation of an Aircraft-Borne Sampling System

Abstract

The U.S. Environmental Protection Agency (EPA), the Florida Department of Environmental Protection (FLDEP), and Texas A&M University collaborated in the design, construction, and testing of a unique, highly crosslinked, Teflon-coated inlet and manifold gas and aerosol sampling system that is being used in EPA aircraft atmospheric pollution characterization studies. The aircraftborne ambient sampling system, which consists of a Teflon-coated shrouded probe coupled to a Teflon-coated aluminum manifold, is designed to collect reactive gases (e.g., mercury and halide species) and aerosols for subsequent analysis and characterization. The shrouded inlet probe was tested for particle transmission ratios in a high-speed aerosol wind tunnel. An existing wind tunnel was upgraded from a maximum wind speed of 13.4 m/s (48 km/h or 30 miles/h) to 50.5 m/s (182 km/h or 113 miles/h) to test this probe. The wind tunnel was evaluated for compliance with the criteria of ANSI 13.1 to establish the acceptability of its use in testing probes. The results demonstrated that the velocity and tracer gas concentration profiles were within the specified limits. A wellcharacterized ThermoAndersen Shrouded Probe (Model RF-2-112) was also tested to check tunnel performance and test methodology. These findings suggest that shrouded probes can be used for low speed (∼100 miles/h) aircraft applications. The transmission ratio of these probes is a significant improvement over the conventional aircraft-mounted, sharp-edged isokinetic diffuser-type inlets.

Reactive mercury in the troposphere: Model formation and results for Florida, the northeastern United States, and the Atlantic Ocean

“…Measurements of Hg 0 and RGM were made from a NOAA Twin Otter aircraft in the vicinity of south Florida during 12 d of flight operations in June 2000, at heights up to 4000 m [ Landis et al , 2005], The aircraft was equipped with a unique shrouded probe inlet and manifold designed specifically for airborne mercury speciation measurements [ Irshad et al , 2004]. Five‐minute integrated Hg 0 measurements were obtained using collocated Tekran Instruments Corporation (Knoxville, Tennessee) Model 2537A mercury vapor analyzers with KCl‐coated multichannel annular denuders incorporated into the inlet system to prevent collection of RGM.…”

A Methodology to Monitor Airborne PM10 Dust Particles Using a Small Unmanned Aerial Vehicle

“…Other variables to consider for isokinetic measurements with aircrafts are: diffusion, sedimentation, and turbulent inertial deposition. However, the variables considered will vary depending on the type of aircraft [ 15 , 16 , 17 ]. Related literature on the topic mainly focuses on fixed wing UAVs which, due to their flight characteristics, can provide better conditions for isokinetic sampling [ 16 , 17 ].…”

Airborne instruments to measure atmospheric aerosol particles, clouds and radiation: A cook's tour of mature and emerging technology

“…Hence it is important to quantify these processes. In principle, there are four ways to accomplish this task: the use of empirical equations from the literature (e.g., given in Baron andWilleke, 2005 or Von der Weiden et al, 2009), Computation Fluid Dynamic (CFD) modeling studies (e.g., Ram et al, 1995;Cain et al, 1998;Twohy, 1998;Dhaniyala et al, 2003;Krämer and Afchine, 2004;Eddy et al, 2006), experimental quantification of particle losses by wind tunnel studies (e.g., Chandra and McFarland, 1997;Cain et al, 1998;Murphy and Schein, 1998;Twohy, 1998;Hegg et al, 2005;Hermann et al, 2001;Irshad et al, 2004) or in-flight testing and comparison (Huebert et al, 1990;Porter et al, 1992;Weber et al, 1999;Blomquist et al, 2001;Huebert et al, 2004;Moore et al, 2004;Hegg et al, 2005).…”