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- Litvinenko, Yu.A., et al.
(författare)
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Experimental investigation of a streaky structure varicose instability in a swept wing boundary layer
- 2004
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Ingår i: Thermophysics and Aeromechanics. ; 11:1, s. 13-22
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Tidskriftsartikel (refereegranskat)abstract
- The investigation results of the controlled experiment of a streaky structure varicose instability in a swept wing boundary layer are presented. The picture of a streaky structure spatial evolution and secondary high-frequency disturbances generated on it is obtained using hot-wire measurements. It is shown that exactly a varicose instability is realized. It has been found that the secondary disturbance increases owing to instability of mean velocity distribution on normal to the wall caused by the streaky structure development. The following features of a varicose breakdown of a longitudinal stationary streaky structure are presented: structure modulation in the longitudinal direction by a secondary disturbance frequency, downstream excitation of new streaky structures, formation and development of nonstationary structures localized in space. In contrast to the boundary layer flow of the unswept wing models, where these structures resemble classical horseshoe structures or lambda-vortices, only one vortex remains on a swept wing from the two making the vortex structure because of the crossflow.
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| 3. |
- Litvinenko, Yu.A., et al.
(författare)
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Nonlinear sinusoidal and varicose instability in the boundary layer (review)
- 2004
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Ingår i: Thermophysics and Aeromechanics. ; 11:3, s. 329-354
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Tidskriftsartikel (refereegranskat)abstract
- Results of studying sinusoidal and varicose instabilities of streaky structures at the nonlinear stage of the laminar-turbulent process in shear flows are presented. The flow behavior in the course of spatial evolution of streaky structures with a secondary high-frequency disturbance generated on them is discussed. Various scenarios of origination and development of coherent vortex structures examined in physical and numerical experiments are considered. Specific features of the development of sinusoidal and varicose cases of destruction of the steady streamwise streaky structure are demonstrated, such as transverse and streamwise modulation of the structure by the secondary-disturbance frequency, appearance of new streaky structures in the downstream direction, and emergence and evolution of unsteady Λ-type structures localized in space in both cases.
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