Investigation of accelerating non-slender delta-wing planforms at high angle of attack using lagrangian coherent structures

A proper understanding of vorticity production, reorientation, and annihilation around and in the wake of complex three-dimensional bodies such as unmanned combat air vehicles (UCAVs) would provide critical insight for effective flow-control development in unsteady environments. Force measurement, surface pressure measurement, and time-resolved planar flow visualization at high Reynolds number for steady and unsteady translations have been carried out on a NACA 0012 airfoil wing with triangular planform geometry. At high angles of attack, the flow field exhibits sensitivity to axial acceleration when initially separated across the midspan. Flow field data analysis included a finite-time Lyapunov exponent analysis shows a topological change in the coherent structure during different axial accelerations.