Download or read book Receptivity of Hypersonic Boundary Layers to Distributed Roughness and Acoustic Disturbances written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2019-01-18 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: Boundary-layer receptivity and stability of Mach 6 flow over smooth and rough 7 half-angle sharp-tipped cones are numerically investigated. The receptivity of the boundary layer to slow acoustic disturbances, fast acoustic disturbances, and vortical disturbances are considered. The effects of two-dimensional isolated and distributed roughness on the receptivity and stability are also simulated. The results show that the instability waves are generated in the leading edge region and that the boundary layer is much more receptive to slow acoustic waves than to the fast waves. Vortical disturbances also generate unstable second modes, however the receptivity coefficients are smaller than that of the slow acoustic wave. An isolated two-dimensional roughness element of height h/delta =1/4 did not produce any difference in the receptivity or in the stability of the boundary layer. Distributed roughness elements produced a small decrease in the receptivity coefficient and also stabilized the boundary layer by small amounts. Balakumar, Ponnampalam Langley Research Center NF1676L-14447