Result s are presented of an experimental investigation of the structure of the velocity field in separated flow arising in the streamline of a semicylinder located on a smooth subjacent surface. The axis of the semicylinder is perpendicular to the incident flow, and the Reynolds number is equal to 2.1*10$^{5}$. The velocity field is studied by means of a two-component mechanotron - based anemometer. The existence of two separation zones is confirmed, with one located in front of and the other behind the semicylinder. In separated flow behind the semi-cylinder, a unique displacement layer is found; the vertical profiles of the longitudinal component of the mean velocity in the separated flow right up to the attachment zone are similar to the profile of the mean velocity in a plane turbulent displacement layer. The measured vertical profiles of the dispersion of the horizontal and vertical velocity components and the moment of correlation of the latter indicate significant spatial irregularity in the region of separated flow of the distribution of the integral characteristics of turbulence in the longitudinal direction. An analysis of the fluctuation autospectra of the velocity showed two statistically significant maxima which follow the semicylinder in the separation zone and corresponding Strouhal numbers from 0.013 to 0.018 and from 0.031 to 0,036.
Faculty of Physics, Moscow State University, Leninskie Gory, Moscow, 119992, Russia
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