Vortex-enhanced capture of airborne particulates

The study reported here sought to exploit aeroelastically-generated vortices for enhanced capture of airborne particles by horizontal, flat plate collectors. Elastically-supported bluff bodies of different cross-sections were screened for suitable plunge (transverse) oscillation at air velocities ranging from about 1 to 10 m s(-1). Both "D" shapes and trapezoidal prisms proved to be particularly effective; the "D" provided an increase in particle capture of 64% relative to the undisturbed flow over a flat plate at a mean air speed of 1.5 m s(-1). At higher velocities, a "T" shaped cross-section (producing mainly torsional oscillation) was found to be extremely effective at increasing capture for airborne particles with a mean diameter of 8 microm. Dynamic pressure measurements made downstream from the oscillators revealed that the torsional oscillation of the "T" produced a flow with multiple periodicities, whereas the plunge oscillators produced a wake that was more sharply periodic. These results indicate that aeroelastically intensified vortices, generated at Reynolds numbers ranging from about 2300 to 5200, can significantly improve particle removal from air streams. Furthermore, the effect can be exploited in both internal (duct) and external (free) flows.