Large Eddy Simulation Research on the Evolution Mechanism of Aircraft Wake Influenced by Cubic Obstacle

Abstract

Aircraft wake is a kind of intense air movement, and the study of its generation, development, and dissipation law is of great significance to the flight safety. There are abundant researches on the evolution of aircraft wakes affected by weather and ground effects; however, there are few studies on the influence of a single obstacle on the evolution of aircraft wake. In this article, in order to explore the influence of a single obstacle on the evolution of aircraft wake, firstly, we develop a computational fluid dynamics-based method of simulation of aircraft wake affected by cubic obstacle of different heights in order to obtain the wake intensity changes and position changes before and after being affected by the obstacle. Then, the result data are visualized and analyzed, and we obtain the results of velocity and $Q$ criterion contours, circulation, and data related to wake vortex structure. CFD simulations are conducted, including the cases of the vertical distance between wake vortex and obstacle which is 20 m, 60 m, 100 m, and no obstacle. The quantitative results indicate that a single obstacle also has a great influence on the evolution of the wake vortex. Obstacle will shorten the time for the wake vortex to enter the fast decay stage, and the smaller the distance the wake vortex is above the obstacle, the faster it enters the fast decay stage. In the same time, the circulation will reduce 20% more under the same calculation time when the wake is 20 m above the obstacle than when the wake is 100 m above the obstacle, and the circulation will reduce 45% more than when there is no obstacle. Single obstacle also leads to the generation of multiple secondary vortices and rotates around the wake vortex, resulting in the increase of wake vortex core radius, wake vortex core spacing, and wake vortex height.