Abstract
Wingtip vortices present a problem of safety and efficiency for aircraft. Vortices are a primary component of wake turbulence, the presence of which requires aircraft take off and landings to be spaced 2-4 minutes apart. This limits the capacity of airports, and causes excess pollution as aircraft are forced to enter holding patterns to maintain spacing. Additionally, wingtip vortices represent regions of low pressure, resulting in increased pressure drag and reduced aerodynamic efficiency.
The Wing Tip Co-Flow Jet (WTCFJ) is based on the Co-Flow Jet (CFJ), developed by Zha and Paxton [1], featuring simultaneous injection and suction of the flow at the wingtip. A NACA 6421 based, aspect ratio 20, rectangular wing is studied nummerically at angle of attack 1◦. The free stream flow is at mach number 0.15 and Reynolds number 2.6 × 106. Three geometric configurations of WTCFJ are studied and compared to a baseline case without WTCFJ. The simulations are carried out using the in-house FASIP CFD code, which utilizes a 3D RANS solver with Spalart-Allmaras (S-A) turbulence model. The objectives of this study are to determine the effect of the WTCFJ on the wingtip vortex, and to determine the effect of altering the momentum coefficient of the WTCFJ on the performance of the wing and WTCFJ system. The results show that the WTCFJ can effectively increase the rate of vortex dissipation with downstream distance relative to the baseline. The peak vorticity magnitude reduces 62.2% between 0.2 and 3 chord lengths downstream of the trailing edge for the baseline. WTCFJ case 2 shows a 73.5% reduction in peak vorticity magnitude and case 4 shows a 80.5% reduction. At the wingtip the vorticity is increased by the WTCFJ compared to the baseline due to the increased strength of the secondary vortices forming at the flat end cap. Aerodynamic performance parameters are also studied. The aerodynamic performance of the baseline is 27.7658, increasing to 28.6418 for case 2 and 35.6234 for case 4. However, power corrected aerodynamic efficiency is lower for case 2 at 27.2291 and 19.7057 for case 4, compared to the baseline at 27.7658.