Aircraft Wake Vortex Core Size Measurements

Abstract

We have examined data from three aircraft field tests designed, in part, to measure the size of the vortex cores generated by the aircraft. The field tests were performed between 1990 and 1997 at Idaho Falls, ID, Wallops Island, VA, and John F. Kennedy International Airport (JFK) in NY. At Idaho Falls, an instrumented 200-foot tower was used to measure velocities in the wakes of Boeing 727, 757 and 767 aircraft flown upwind of the tower. In the Wallops Island test, velocities and smoke trails behind a Lockheed-Martin C-130 aircraft were measured by an instrumented North-American Rockwell OV-10 aircraft flown behind the C-130. For the JFK tests, the vortex wakes of landing aircraft were measured by a Continuous Wave lidar operated by MIT/Lincoln Laboratories. The results from all three field tests are quite consistent, and suggest that the size of the velocity cores in trailing vortices behind an aircraft is on the order of one percent of the wingspan of the aircraft, where core size is defined as the radial distance from the vortex center to the point of maximum tangential velocity. We note that numerical simulations of trailing vortex evolution typically use velocity vortex core sizes in the range from five to twelve percent of the wingspan of an aircraft. Thus, the values of velocity core size used in numerical models are significantly larger than the full-scale values reported here. We also show that a typical size of smoke trails, where smoke is used to visualize the vortices behind an aircraft, is approximately twice the size of the velocity core.

Wind Impact on Single Vortices and Counterrotating Vortex Pairs in Ground Proximity

“…The selected vortex core size of r c /b 0 = 0.0625 satisfies the equilibrium of the energy consumed by the induced drag of a slightly outboard loaded wing with a spanwise load factor of s = 0.84 and the crossflow kinetic energy of the vortices [46]. On the other hand, vortex core size measurements suggest that the cores may be as compact as one percent of the wingspan of the aircraft [47].…”

Computational Modelling of Wing Downwash Profile with Reynolds-Averaged and Delayed Detached-Eddy Simulations

“…At this short distance, it is very likely that the vortex is still developing and shows that the wing tip vortex has little effect on the tail as these velocities diminish exponentially. 14,15 This can also be observed with the Biot-Savart law 7 relating the tangential velocity to a point at distance r from the vortex filament:…”

“…The characteristic tangential velocity profile is also observed. However, when comparing the results to three idealized models of trailing wake vortices, 15 results differ. The estimation of the vortex strength by initial circulation Γ 0 , for the calculation of tangential velocities with the idealized models is given by: …”

Dynamic soaring of unmanned aerial vehicle within airliner wake vortex in climb regime

“…A vortex core radius size differs in literature within the range of 1 to 7 % of vortex generating airplane span. An initial core size and growth rate was obtained from the literature 11,12,13 . The initial core size value of 1 % of airliner span was used in the extreme formation analysis.…”