Identification of Trailing Vortex Dynamic States

Abstract

Flight research of the characteristics of trailing vortices, generated by heavy jet transport aircraft in cruising flight, was conducted. Trailing vortex velocities were derived by vectorial differencing of aircraft inertial velocity and true airspeed vectors, and then transforming to the vortex mean axis. Lateral distances between port and starboard vortices were 60–70% of generator wingspan. Vortex core radii were derived. Core pressure states were expanded or diffused. Core diffusion was associated with axial segmentation. Core pressure expansions included magnitudes greater than Euler equilibrium values, with velocity profiles displaying peaked maxima. Associated with these characteristics was vortex core radial instability. Subsequent radial expansion and contraction resulted in a large range of rC values. Vorticity confined to an annular state and discretized into circular arrays of N-point vortices of small rC was prevalent. Radial profiles of vortex velocity were identified and included Rankine (peaked) profiles, Lamb-Oseen, and Burnham-Hallock rounded profiles. Twenty-five percent of identified profiles were rounded. The majority of profiles were peaked, with maxima greater than, or equal to, Rankine values. Temperature gradients inside and outside of core edges were identified: outside, heating occurred, inside, cooling. Outer heating occurred with upstream axial flow. Inner cooling occurred with downstream axial flow.