Distributed acoustic receptivity in laminar flow control configurations

A model problem related to distributed receptivity to free‐stream acoustic waves in laminar flow control (LFC) configurations is studied within the Orr–Sommerfeld framework, by developing a suitable extension of the Goldstein–Ruban theory for receptivity due to localized disturbances on the airfoil surface. One advantage of the proposed method is that it easily permits the prediction of receptivity due to a wide class of noncompact distributions for surface nonuniformities, such as small‐amplitude variations in suction velocity and surface admittance. The results, thus, complement the earlier work on the receptivity produced by local variations in these two quantities. It is shown that the cumulative effect of distributed receptivity can be substantially larger than that of a single, isolated suction strip or slot. Furthermore, even if the receptivity is spread out over very large distances, the most effective contributions come from a relatively short region in the vicinity of the lower branch of the neu...