Acoustic imaging of aircraft wake vortex dynamics

Abstract

The experience in utilizing a phased microphone array to passively image aircraft wake vortices is highlighted. It is demonstrated that the array can provide visualization of wake dynamics similar to smoke release or natural condensation of vortices. Examples on how the technique has been integrated with other data to address some of the research issues in wake vortices are documented. These topics include the initial vortex spacing characterization, collaboration with simultaneous pulsed Lidar data to provide a more complete understanding of vortices at a late stage in their evolution, and correlation between atmospheric turbulence with the time-scale involved for vortices developing into a very contorted state. In addition, the paper provides a comparison between the vortex tracks as inferred from their acoustics characteristics vs. those detected from the velocity field (i.e., pulsed Lidar). A preliminary attempt is also made to examine the global link between wake vortex sound and vortex circulation, suggesting that there could be a power law relationship between the two datasets.