The Role of Laminar Separation Bubbles on the FX 63-137 Airfoil

Abstract

Low Reynolds number airfoils are prone to be adversely affected by the presence of laminar separation bubbles (LSB). But at relatively high Reynolds number (based on the chord of the airfoil) in the range of 100,000–200,000, suppression of LSB, by a boundary layer trip, caused the performance of the airfoil to deteriorate further. In this particular case boundary layer trip does not result in an overall drag reduction due to suppression of the laminar separation bubble, as conventional wisdom would have suggested. The trip causes the turbulent boundary layer to separate early, at relatively high angles of attack, and augmenting the form drag.