Loads and Pressure Characteristics on a Wing in Transverse Traveling-Wave Gusts

A finite-span NACA0009 wing is tested in the Andrew Fejer Unsteady Wind Tunnel to study the aerodynamic loads and surface pressure features during transverse gust encounters. Under traveling-wave perturbations, the lift and pitching moment responses of the wing demonstrate a dependency on the effective angular rate and the suction distributions affected by flow separation. Sparse surface pressure measurements are used to develop reduced-order models based on a proper orthogonal decomposition (POD) approach. The spatial integrals connect the POD modes to the unsteady aerodynamic loads with a physical interpretation. The lift and pitching moment estimations made by the modes show reasonable correlations with experimental measurements. An improvement of this approach is pre-examined with simulation data, suggesting that the POD spatial integrals can achieve higher performance with pressure data available on both the suction and pressure sides of the wing.