微型涡流发生器影响下的湍流边界层流场与摩阻特性

The present work uses the stereoscopic particle image velocimetry and calibration-free dual hot-film wall shear stress measurement sensor to measure the flowfield and friction at downstream of the one array of forwards wedge Micro Vortex Generator (MVG) in the turbulent boundary layer at moderate Reynolds number. The result of flowfield measurement shows that MVG produces the streamwise velocity defect regions and streamwise vortices pairs in downstream time-averaged flowfield, which causes the second outer-peak in the spanwise pre-multiplied energy spectra. The result of proper orthogonal decomposition shows that the contribution of energy of structures induced by MVG is equivalent to the that of large-scale structures and very large-scale structures in the smooth-wall turbulent boundary layer, which also significantly affects the spatial distribution of the near-wall structures. The friction measurement experiment shows that MVG array with higher height and closer spanwise arrangement has higher friction drag reduction. The drag reduction effect of MVG lasts downstream to 80 times of its own characteristic height.