Heat Transfer Enhancement of a Flat Plate Boundary Layer Distributed by a Square Cylinder: Particle Image Velocimetry and Temperature-Sensitive Paint Measurements and Proper Orthogonal Decomposition Analysis

The current empirical study was conducted to investigate the wall neighborhood impact on the two-dimensional flow structure and heat transfer enhancement behind a square cylinder. The low- velocity open-circle wind tunnel was used to carry out the study tests considering the cylinder diameter (D)-based Reynolds number (ReD) of 5130. The selected items to compare were different gap height (G/D= 0.0, 0.1, 0.2 and 0.8). The flow field was measured using particle image velocimetry (PIV) with high image-density camera. The PIV-derived time-averaged quantities, including the streamline pattern, streamwise velocity fluctuation intensity, and reverse-flow intermittency, were examined for the flow past the square cylinder. The measurements of PIV were decomposed with the help of proper orthogonal decomposition (POD) approach that provides a proper view of the POD modes. To obtain the value of the heat transfer enhancement behind the square cylinder, the full-field temperature distributions of flat plate were measured through the temperature-sensitive paint (TSP) technique. Results showed that the maximum heat transfer enhancement was obtained at G/D=0.2 due to the high unstable flow near the wall.