Wall Pressure Signature in Compressible Turbulent Boundary Layers

摘要

Large-scale turbulent flow structures associated with positive and negative wall pressure fluctuations in a compressible turbulent boundary layer are investigated. Experiments are conducted in a closed-loop transonic wind tunnel at Ma = 0.5-0.8, Re_τ = 5,100-9,500 with combined velocity field and wall pressure measurements. Both, velocity and pressure statistics are analysed and compare well with existing low Mach number data. Spatial two-point correlation is applied to determine the size and orientation of the large-scale flow structures, which depending on the wall height have an averaged length scales of 4-6 δ and a maximum inclination angel of ≈ 12°-13°. The wall pressure fluctuations are associated with shear layer structures and it is shown that positive pressure fluctuations are correlated with low speed large-scale flow structures over streamwise extents of 4-5 δ.