Experimental investigation of boundary layer transition on a swept flat plate under variable Reynolds number

• Published in: Fluid dynamics 2022-06, Vol.57 (3), p.318-327
• Main Authors: Lu, X. G., Yi, S. H., He, L., Gang, D. D., Ding, H. L.
• Format: Article
• Language: English
• Subjects: Boundary layer transition; Classical and Continuum Physics; Classical Mechanics; Cross flow; Engineering Fluid Dynamics; Flat plates; Flow visualization; Fluid flow; Fluid- and Aerodynamics; Laminar boundary layer; Physics; Physics and Astronomy; Reynolds number; Turbulence; Wind tunnels
• ISSN: 0015-4628; 1573-8507
• DOI: 10.1134/S0015462822030107

— The experimental study on the transition process of a boundary layer on a 45° swept flat plate is performed in the Mach 6.0 hypersonic low-noise wind tunnel. The instantaneous fine structures of the boundary layer under various Reynolds numbers on the swept flat plate in spanwise planes have been investigated based on the Nano-tracer Planar Laser Scattering (NPLS) technique, respectively. The experimental unit Reynolds number varied from 1.04 × 10 7 to 2.61 × 10 7 m –1 . The characteristics of spatial-time evolution of the boundary layer translating from laminar to turbulence are analyzed.The results show that with increase in the Reynolds number, the front advance of boundary layer transition on the windward side of the swept flat plate is ahead of schedule, and the transition planeis generally parallel to the leading edge of the 45° swept flat plate.The main reason that turbulence in the boundary layer develops at a short distance is due to the influence of cross-flow.Combined with the cross-flow band structure in NPLS flow visualization images, the characteristics of cross-flow wave are studied, and the influence of cross-flow wave in the boundary layer on boundary layer transition is analyzed.