Vortex Wakes of Conventional Aircraft

Vortex Wakes of Conventional Aircraft
Author: Coleman duPont Donaldson
Publisher:
Total Pages: 92
Release: 1975
Genre: Turbulence
ISBN:

A review is made of the present state of our knowledge of the vortex wakes of conventional aircraft. Included are discussions of wake rollup, geometry, instability, and turbulent aging. In the light of these discussions, a brief review is made of the persistence of vortices in the atmosphere, and design techniques which might be used to minimize wake hazard are considered.

Vortex wakes of Aircrafts

Vortex wakes of Aircrafts
Author: A.S. Ginevsky
Publisher: Springer Science & Business Media
Total Pages: 166
Release: 2009-07-07
Genre: Mathematics
ISBN: 3642017606

Investigation of vortex wakes behind various aircraft, especially behind wide bodied and heavy cargo ones, is of both scientific and practical in terest. The vortex wakes shed from the wing’s trailing edge are long lived and attenuate only atdistances of10–12kmbehindthe wake generating aircraft. The encounter of other aircraft with the vortex wake of a heavy aircraft is open to catastrophic hazards. For example, air refueling is adangerous operationpartly due to thepossibility of the receiver aircraft’s encountering the trailing wake of the tanker aircraft. It is very important to know the behavior of vortex wakes of aircraft during theirtakeoff andlanding operations whenthe wakes canpropagate over the airport’s ground surface and be a serious hazard to other depart ing or arriving aircraft. This knowledge can help in enhancing safety of aircraft’s movements in the terminal areas of congested airports where the threat of vortex encounters limits passenger throughput. Theoreticalinvestigations of aircraft vortex wakes arebeingintensively performedinthe major aviationnations.Usedforthispurpose are various methods for mathematical modeling of turbulent flows: direct numerical simulation based on the Navier–Stokes equations, large eddy simulation using the Navier–Stokes equations in combination with subrigid scale modeling, simulation based on the Reynolds equations closed with a differential turbulence model. These approaches are widely used in works of Russian and other countries’ scientists. It should be emphasized that the experiments in wind tunnels and studies of natural vortex wakes behind heavy and light aircraft in flight experiments are equally important.

Flight Test Investigation of the Vortex Wake Characteristics Behind a Boeing 727 During Two-Segment and Normal ILS Approaches

Flight Test Investigation of the Vortex Wake Characteristics Behind a Boeing 727 During Two-Segment and Normal ILS Approaches
Author:
Publisher:
Total Pages: 142
Release: 1975
Genre:
ISBN:

A series of flight tests were performed to evaluate the vortex wake characteristics of a Boeing 727 (B727-200) aircraft during conventional and two-segment ILS approaches. Twelve flights of the B727, equipped with smoke generators for vortex marking, were flown wherein its vortex wake was intentionally encountered by a Lear Jet model 23 (LR-23) or a Piper Twin Comanche (PA-30); and its vortex location during landing approach was measured using a system of photo-theodolites. The tests showed that at a given separation distance there were no readily apparent differences in the upsets resulting from deliberate vortex encounters during the two types of approaches. Timed mappings of the position of the landing configuration vortices showed that they tended to descend approximately 91 meters (300 feet) below the flight path of the B727. The flaps of the B727 have a dominant effect on the character of the trailed wake vortex. The clean wing produces a strong, concentrated vortex. As the flaps are lowered, the vortex system becomes more diffuse. Pilot opinion and roll acceleration data indicate that 4.5 nautical miles would be a minimum separation distance at which roll control could be maintained during parallel encounters of the B727's landing configuration wake by small aircraft. This minimum separation distance is generally in scale with results determined from previous tests of other aircraft using the same roll control criteria. (Author).

Aircraft Wake Turbulence and Its Detection

Aircraft Wake Turbulence and Its Detection
Author: John Olsen
Publisher: Springer Science & Business Media
Total Pages: 599
Release: 2012-12-06
Genre: Technology & Engineering
ISBN: 1468483463

The combination of increasing airport congestion and the ad vent of large transports has caused increased interest in aircraft wake turbulence. A quantitative understanding of the interaction between an aircraft and the vortex wake of a preceding aircraft is necessary for planning future high density air traffic patterns and control systems. The nature of the interaction depends on both the characteristics of the following aircraft and the characteristics of the wake. Some of the questions to be answered are: What deter mines the full characteristics of the vortex wake? What properties of the following aircraft are important? What is the role of pilot response? How are the wake characteristics related to the genera ting aircraft parameters? How does the wake disintegrate and where? Many of these questions were addressed at this first Aircraft Wake Turbulence Symposium sponsored by the Air Force Office of Sci entific Research and The Boeing Company. Workers engaged in aero dynamic research, airport operations, and instrument development came from several count ries to present their results and exchange information. The new results from the meeting provide a current picture of the state of the knowledge on vortex wakes and their interactions with other aircraft. Phenomena previously regarded as mere curiosities have emerged as important tools for understanding or controlling vortex wakes. The new types of instability occurring within the wake may one day be used for promoting early dis integration of the hazardous twin vortex structure.