Trailing-edge flow about unstalled plunging airfoil computed by Euler method

Abstract

The flow around the trailing edge of a sinusoidally plunging NACA 0012 airfoil at zero mean angle of attack and low speed is studied by an unsteady compressible Euler flow solver. The Euler-computed load distribution is decomposed into harmonic components. The first component is dominant and compared with the classical linear theory. The Euler computation predicts the load magnitude approaching zero toward the trailing edge as the linear theory predicts when the reduced frequency is below about 0.4. When the reduced frequency is beyond about 0.4, the Euler solution yields a non-zero load magnitude and a load phase lag for the aft-load and the deviation from the linear theory increases with reduced frequency (0.4 - 4.0) and free-stream Mach number (0.05 - 0.2). The Euler solver is validated by a water-tunnel visualization of near wake in the literature. The computed aftload behavior and flow around the trailing edge are qualitatively confirmed with available experimental data and Navier-Stokes computation.