Experimental study of the wake of a truncated wall-mounted circular cylinder at high Reynolds numbers

The paper presents the Particle Image Velocimetry (PIV) analysis of the wake of the wall mounted truncated cylinder with an Aspect Ratio (AR) of 4 at a range of high Reynolds numbers from 6.4*10 4 to 2.41*10 5 . The velocity distributions are measured using a two-dimensional three-components PIV(2D-3C PIV) system in two horizontal sections. In order to choose a proper measurement window,preliminary smoke tests are conducted. The snapshots of the velocity field are subjected to the Proper Orthogonal Decomposition (POD) analysis in order to understand the structure of the unsteady flow.The influence of the Reynolds number on the POD modes and the distribution of the fluctuation energy among the velocity components are studied. Additionally, a so-called amplitude analysis for each of the first three strongest modes is conducted in order to give a physical interpretation to each of them. The mode structures have been found to remain similar in the mention Re range, so the complete description of the POD results is given for Re = 1.28*10 5 . The most modes are connected to symmetric (about x-axis) fluctuations of the wake in transversal, vertical or longitudinal directions. At the top of the cylinder the wandering and the change of the tip vortices’ (TV) intensity also contribute to the fluctuation energy. In the considered measurement windows the modes which could be associated with the von Karman vortex shedding have not been identified.

Subjects

Truncated Cylinder

Unsteady Flow

Particle Image Velocimetry

Proper Orthogonal Decomposition

DDC Class

620: Engineering

600: Technology

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Experimental study of the wake of a truncated wall-mounted circular cylinder at high Reynolds numbers