Unsteady Aerodynamic Characteristics of a Blade in Pitching Oscillation with Flow Separation : 1st Report.: The Case with Laminar Separation Bubble

Abstract

Unsteady aerodynamic characteristics are investigated in detail by analysing chordwise distributions of unsteady pressures obtained on Go-801 airfoil oscillating in pitch with a separation bubble which shows a nature of so-called short bubble. The mechanism of energy transfer between an oscillating blade and an air flow is made clear by utilizing the chordwise distribution of energy transfer, and the effects of the separation bubble on flutter characteristics are clarified. In addition, the validity of potential flow theory is examined and a simple model of a blade oscillation considering the angle of attack relative to main flow is applied to explain the effects of the location of pitching center.