Control method for aircraft wake vortex based on Rayleigh-Ludwig instability

Abstract

The aircraft wake vortex is an inherent flow phenomenon due to the lift generation mechanism,which has a negative impact on the flight safety. By adding a set of specially designed spoiler,a rectangular wing was designed to generate a pair of weaker vortices,which had different sizes and opposite direction compared to main wing vortices,thereby constructing a self-destructive four-vortex wake system to induce Rayleigh-Ludwig instability. Under different experimental conditions,in terms of changing the size or shape of the spoiler,towing speed and angle of attack,the wake vortex development of the test model,that both with and without spoiler,as well as the circulation analysis,were acquired particle image velocimetry( PIV) measurements under the low Reynolds number. The study demonstrates that the decrease in circulation was 35% to55% in 45 wingspans when spoilers are introduced,whereas the counterpart of the baseline airfoil,without spoilers,is nearly kept steadily,which reveal the application possibility of Rayleigh-Ludwig instability in alleviating the wake vortex. As the initial circulation ratio equals to- 0. 489 and the initial distance ratio is0. 5,the circulation of the primary vortex reduce most significantly( 55. 9%) in 45 wingspans. Results would provide a scheme in the design of airfoils with weaker vortices.