Accession Number : ADA267204


Title :   Boundary Layer Receptivity Theory


Descriptive Note : Final rept. 15 Nov 89-14 Oct 92,


Corporate Author : ARIZONA UNIV TUCSON COLL OF ENGINEERING AND MINES


Personal Author(s) : Kerschen, Edward J


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a267204.pdf


Report Date : Mar 1993


Pagination or Media Count : 20


Abstract : Receptivity processes by which free-stream disturbances generate Tollmien-Schlichting waves in boundary layers have been analyzed using asymptotic methods for high Reynolds numbers. Vortical and acoustic free-stream disturbances have been considered. Receptivity occurs in the vicinity of the leading edge, and in localized regions further downstream where some feature (e. g., a wall hump) produces a short-scale disturbance to the mean flow. Nonlinear effects related to the free-stream pressure field have been found to play an important role in localized receptivity to vortical disturbances. For leading- edge receptivity, the influences of the body nose radius and aerodynamic loading in the leading-edge region have been analyzed. In the absence of aerodynamic loading, an increase in the body nose radius decreases the leading-edge receptivity coefficient. However, strong aerodynamic loading leads to a dramatic increase in the leading-edge receptivity coefficient, negating the decrease due to a larger nose radius. The propagation of an instability wave past a junction between a rigid wall and a surface with non-zero compliance or admittance has also been analyzed. The junction can cause energy to be scattered from the instability wave to higher eigenmodes, effectively attenuating the instability wave.


Descriptors :   *BOUNDARY LAYER , *AERODYNAMIC LOADING , *FLUID DYNAMICS , PROPAGATION , LAYERS , VORTICES , SURFACES , COEFFICIENTS , WALLS , FLOW , RECREATION , REYNOLDS NUMBER , INSTABILITY , NOSES , BODIES , FREE STREAM , NUMBERS , JUNCTIONS , MEAN , ADMITTANCE , STREAMS , LEADING EDGES , PRESSURE , ASYMPTOTIC SERIES , NONLINEAR SYSTEMS , REGIONS , EDGES , ENERGY


Subject Categories : Fluid Mechanics


Distribution Statement : APPROVED FOR PUBLIC RELEASE