Ramesh K Agarwal
Washington University in St Louis, USA
Title: Aerodynamics of a transonic airfoil in ground effect
Biography
Biography: Ramesh K Agarwal
Abstract
The Wing In Ground Eff ect (WIG) aircraft operates with larger lift to drag ratio compared to a conventional aircraft at low subsonic Mach numbers. To increase the traffi c volume of the WIG aircraft , one possible way is to increase the fl ight speed, which can result in transonic fl ow. Currently, the studies on the transonic fl ight in ground eff ect are very few. Th e focus of this paper is to study aerodynamics and fl ow physics of a typical transonic RAE2822 airfoil at Angles of Attack (AOA) from 0 to 12 deg. and Mach numbers from 0.5 to 0.8 in ground eff ect by varying the ground clearance above the ground. Th e compressible Reynolds-Averaged Navier-Stokes equations with Spalart-Allmaras (SA) turbulence model are solved using the commercial Contract for diff erence (CFD) solver ANSYS Fluent. For fl ight near the fl at ground surface, some interesting shock formations and fl ow phenomenon are obtained due to transonic fl ow. For the unsteady shock buff et phenomenon on the upper surface, the buff et boundary in the Angle of Attack (AOA) Mach number (Ma) plane shrinks with the decreasing ground clearance. Compared to the unbounded fl ow fi eld, there exists a steady shock on the lower surface of the airfoil in ground eff ect for low AOA’s because the channel between the lower surface of the supercritical airfoil and the ground is a typical convergingdiverging shape, resulting in the decrease in lift and increase in drag. For extreme conditions of very small ground clearance, small AOA and high Mach numbers, a new coupling between the shock buff ets on the lower and the upper surface of the airfoil is observed. Th e unsteady aerodynamics of transonic fl ow in the presence of a wavy ground is also analyzed.