Wind tunnel study of odor plume structure in the wake of a commercial odor-delivery device

We conduct laboratory experiments to quantify the spatiotemporal dynamics of odor plumes forming in the wake of a Training Aid Delivery Device (TADD). The TADD is a cylindrical glass jar topped with an odor-permeable membrane created for the US Army as an aid for training military working dogs for scent detection and localization. We use a photo-ionization detector (PID) instrument that is sensitive to vapors from volatile organic compounds (VOCs) to map negatively buoyant odor fields emanating from a TADD containing liquid acetone. The TADD is placed on the floor of a low-speed wind tunnel and an automated traverse translates the PID to measure three-dimensional odor concentration fields downwind of the TADD. Results show that the odor exiting the TADD membrane interacts with the horseshoe vortex structure formed by the interface between the bottom boundary layer and the TADD. This process creates an odor plume that has bimodal peaks away from the centerline and lower concentrations directly downwind. We investigate the effect of mean crossflow velocity in the tunnel and compare the results with numerical simulations presented in a companion poster.