Evolution of vortical structures behind an inclined flat plate

2D3C TR-PIV technique was utilized to investigate streamwise-oriented vortical structures behind an inclined flat plate. The angle of attack was set to 7 deg, several fields of view in the wake were investigated. The instantaneous velocity vector fields were captured, dynamics of the flow was studied using POD method. The streamwise structures are determined by vorticity and low- and high-velocity streaks are defined. The acquired results are in a good agreement with the new hypothesis of a principle of flight.

Experimental measurement of large-scale three-dimensional structures in a turbulent boundary layer. Part 2. Long structures

Three-dimensional (3D) measurements of a turbulent boundary layer have been made using high-speed particle image velocimetry (PIV) coupled with Taylor's hypothesis, with the objective of characterising the very long streamwise structures that have been observed previously. The measurements show the 3D character of both low- and high-speed structures over very long volumes. The statistics of these structures are considered, as is their relationship to the important turbulence quantities. In particular, the length of the structures and their wall-normal extent have been considered and their relationship to the other components of the velocity fluctuations and the instantaneous stress.

ON THE RESPONSE OF SHOCK-INDUCED SEPARATION BUBBLE TO SMALL AMPLITUDE DISTURBANCES

Numerical simulations of an oblique shock interacting with a compressible laminar boundary layer are reported. The Mach number ranges from 2 to 6.85, while the Reynolds number based on the distance to the impingement location is fixed at 3 × 105. All the simulations are carried out with a constant wall temperature, equal to the adiabatic recovery temperature. At higher shock strength the evolved separation bubbles are taller and are biased towards the upstream side of the impingement location with an asymmetrical structure. Existing similarity scalings for the bubble length need to be modified for the high Mach number range. Introduction of small amplitude disturbances upstream of the separation bubble resulted in the growth of organised streamwise structures downstream of the bubble.