Relationship Between Vortex Meander and Ambient Turbulence

Guidelines for Avoiding Vortex Wakes During Use of Closely-Spaced Parallel Runways

“…Previous studies have examined the details of various aerodynamic mechanisms that cause the vortex wakes of subsonic aircraft to spread and to move. [12][13][14][15][16][17][18][19][20] This paper first presents an overview of the results of the research conducted on the wake-spreading and movement mechanisms that influence the time at which intrusion of wake components into the airspace of following aircraft will occur. Estimates carried out by use of a computer program based on previous studies (see Appendix) indicate guidelines that may be used to expedite the volume of aircraft operations safely and efficiently onto closely-spaced parallel runways.…”

“…If this is to be done safely, the theoretical estimates of wake movement and spreading must be reliable, with few if any uncertainties. The prediction of wake-spreading as a function of time, and the way that atmospheric conditions affect this aerodynamic problem [12][13][14][15][16][17][18][19][20] are first summarized in order to develop a reliable computational method for prediction of the duration of the safe zone illustrated in Fig. 1.…”

“…Only an overview of previous results is presented here because considerable attention has already been given to the details of the aerodynamics of how vortices move and spread. [12][13][14][15][16][17][18][19][20] In this work, the movement and spread of lift-generated vortex wakes by aerodynamic means has been divided into the following mechanisms:…”

“…The motion and spread of wake-hazardous regions predicted by use of maximum measured values of the wind and gust velocities, is believed to be conservative, because, as mentioned previously, wind-tunnel observations of vortex meander indicate that vortex elements only move about 40% of the amount predicted by wind magnitude. 19 Again, the difference between the two values needs to be studied by use of flight tests. .…”

On Data Scatter in Measured Linking Times for Lift-Generated Vortex Pairs

“…1 Another part of the foregoing research program was directed at finding effective and efficient ways to avoid the vortex wakes of preceding aircraft. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] The present research effort does not attempt to reduce the in-trail time between aircraft landing on the same runway, because the increase [2][3][4][5][6] in airport capacity to be achieved is less than about 10%. In contrast, it is estimated that the capacity of airports can be safely increased by a factor of two or more by use of an improved wake-avoidance method for airport operations on sets of closely-spaced parallel runways.…”