The design and characterization of a streamlined, high-volume particle impactor used for trace chemical analysis is presented. The impactor has a single round jet and is designed to operate at a flow rate of 1000 LPM. Computational fluid dynamics was used as a tool to optimize the aerodynamic performance of the impactor by iteratively redesigning the geometry and curvature of the internal walls. By eliminating recirculation zones within the flowfield of the impactor and using flowfield streamlines as new walls, successive designs revealed a tremendous reduction in the pressure drop across the impactor. The impaction surface itself is easily removed from the body of the impactor assembly, facilitating rapid trace chemical analysis using a variety of chemical detection techniques. A prototype impactor was printed with a 3D printing machine and characterized in terms of cut-off diameter using an Ink Jet Aerosol Generator and fluorescence intensity measurements. The actual cut-off diameter was not able to be measured because the smallest aerosol particles that could be tested were 1.86 µm and were collected at 100% efficiency. Particulate contamination from the high-explosive compound C4 was also collected with the impactor to demonstrate operational utility for trace explosives detection.
Citation: Aerosol Science and Technology
Pub Type: Journals
particle collection, impactor, computational fluid dynamics, trace explosives detection, 3D printing, inkjet printing