Aerodynamic effects of dent holes on airfoils under subsonic and supersonic flow conditions

Abstract

This research investigates the aerodynamic performance of airfoils in both subsonic and supersonic flows, focusing on the impact of non-symmetric and symmetric surface dents. Unlike previous studies that primarily considered symmetric or regularly spaced dimples, this study explores the effects of isolated dents—hemispherical, conical, and cylindrical—placed at various chordwise locations on both the upper and lower surfaces of the airfoil. Computational simulations were conducted using ANSYS Fluent. A total of 54 simulations were performed for a three dimensional NACA 0012 airfoil under subsonic conditions, with Reynolds numbers ranging from 1.9 × 10⁶ to 8.3 × 10⁶ and angles of attack from −12° to +12°. Additionally, nine two-dimensional simulations were carried out for a double-wedge air foil at Mach number 3 to assess performance in the supersonic regime. The results demonstrate that the geometry, location, and surface area of dents significantly influence aerodynamic behavior. In subsonic flow, the highest lift-to-drag ratio of 49.6 was achieved with a hemispherical dent located at the mid-chord on the upper surface, indicating improved boundary layer control and delayed flow separation. In supersonic flow, a trailing dent placed at the leading edge of the lower surface generated lift even at zero angle of attack, doubling the lift-to-drag ratio compared to the clean airfoil. These findings were validated by benchmarking clean airfoil simulations against NASA’s NACA 0012 data and existing literature, showing good agreement in pressure distribution and drag values. Overall, the study provides compelling evidence that non-symmetric dents can function as effective passive flow control mechanisms, with potential applications in UAVs, missiles, and other high speed aerospace platforms.