Sound generated by an elastic wing actuated at its leading edge.

Abstract

The sound generated by a thin elastic plate, subject to uniform low‐Mach flow and to leading‐edge pitching and heaving motions, is studied. The linearized plate motion is analyzed under conditions where the unforced plate (in the absence of leading‐edge actuation) is stationary. When the frequency of applied forcing coincides with an eigenfrequency ωres of the unforced plate, a resonance motion is excited and the plate oscillates at the corresponding eigenmode. The sources of sound in the problem include the plate velocity and fluid vorticity. Acoustic radiation of dipole type is calculated and discussed in the limit of an acoustically compact plate. It is found that plate elasticity has two opposite effects on sound radiation: close to ωres, elasticity results in the generation of high sound pressure levels; however, far from ωres, elasticity tends to reduce the amplitude of plate deflection (compared to that of a rigid plate), leading to reduced sound levels. It is also shown that the release of trailin...