Parametric Study of Crow Instability in Aircraft Wake Vortices Using Large Eddy Simulation

Wake Vortices;Crow Instability;Interaction Among Vortices;Large Eddy Simulation (LES);621

공과대학 기계항공공학부 ;

University:서울대학교 대학원

关键词: Wake Vortices;    Crow Instability;    Interaction Among Vortices;    Large Eddy Simulation (LES);    621;   

Others  :  http://s-space.snu.ac.kr/bitstream/10371/141398/1/000000151288.pdf

美国|英语

来源: Seoul National University Open Repository

【 摘 要 】

Aircraft wake vortices are not easily dissipated so they stay in the atmosphere for a certain period of time. It is known that the transport and decay of wake vortices are closely related to the phenomenon called Crow instability. A parallel pair of wake vortices links due to the long-wave sinusoidal instability, and forms a ring while dissipating rapidly. To predict the behavior of wake vortices, research has been conducted dealing with the effect of atmospheric conditions such as eddy dissipation rate, and stratification level. In various conditions, only a single pair of wake vortices was superimposed to the computational domain. However, there is a possibility of interactions among vortices where runways are parallel so that a pair of vortices from an aircraft moves to another runway path due to crosswind. In addition, the interaction can happen where the flight paths are crossing each other, so it is necessary to analyze the difference between the behavior of a pair of wake vortices and the transport and decay of two pairs of wake vortices. In this paper, parametric study of aircraft wake vortices are conducted using large eddy simulation (LES) turbulence model. Vortex parameters were selected for light, medium, and heavy aircraft and the velocity distribution of a vortex was modeled using Burnham-Hallock vortex model. As a result, it was confirmed that the vortex lifespan was shortened in light – medium interaction. In medium – medium interaction case, the circulation strength became temporarily stronger as vortices were combined and then they were dissipated. It was also found that in medium – heavy interaction case, the linking of vortices from heavy aircraft happened 5 times faster than the case of a single pair of vortices from heavy aircraft without interaction. Since the vortices from large aircraft have high circulation which maintains for a long time, the results from medium – heavy interaction case can be reflected to the adjustment of separating interval between airplanes to improve airport efficiency.