Unsteady Aerodynarnic Characteristics of Abrupt Stall Type Airfoil in Pitching Oscillation near Stall Angle of Attack : 1st Report, On Dynamic Characteristics of Flow Separation and Regions Corresponding to Separation Patterns

Abstract

Using an abrupt stall type airfoil, which shows the nature of abrupt change in the static moment curve as the increment of angles of attack due to the sudden change of separation pattern to the leading edge separation, are investigated experimentally the unsteady aerodynamic characteristics of the airfoil in pitching oscillation near stall angle of attack. The aspects of the change of separation pattern during oscillation in this region of angle of attack are clarified in detail. The effects of mean angle of attack, reduced frequency, amplitude of pitching oscillation and location of pitching axis on the unsteady stall characteristics are made clear, and the region corresponding to separation patterns are defined.