Non - localized acoustic
نویسندگان
چکیده
Acoustic receptivity was experimentally examined for a Blasius boundary layer with receptivity sites in the form of 2-D waviness and oblique waviness. Linear receptivity coeecients obtained for all values of forcing combinations (h) are in good agreement with receptivity theory. The measured receptivity increased markedly with increasing wave obliqueness. Detuning was investigated by varying the streamwise wavenumber, w, of the 2-D and oblique wall waviness. Oblique transition was also investigated by exciting a pair of oblique Orr-Sommerfeld (O-S) modes (f=fo; ==w) = (1; 1). For large values of h, a secondary instability was observed that ultimately lead to laminar breakdown. This instability appears to be driven by large spanwise velocity gradients, jdU=dd j.
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