Experimental investigation of flexible-fixed obstacle effects on the heat transfer

In this thesis, the heat transfer performance of both the obstacles in different geometries and the flexible-fixed plates placed in these obstacles were investigated experimentally. The obstacles geometries, flexible-fixed plate's lengths (L), widths (w) and heights from the test region (c) were changed. The four different obstacle geometries, the triangular shaped obstacle (U-KE), the cylindrical shaped obstacle (S-KE), the quadrangle shaped obstacle (D-KE) and the half-cylinder shaped obstacle (YS-KE) are located in the channel entrance. The Reynolds number in the measurements was changed between 4983-34878 Heat transfer results were obtained by using thermal imaging technique. Optimum values of design parameters were determined by using Taguchi experimental design method and experimental studies were performed depending on the determined parameters. Six experimental parameters that influence the heat transfer and pressure loss with flexible-fixed plates were analyzed using the Taguchi method. Thus, L16 (44x22) orthogonal sequences consisting of these parameters were selected for the experimental design. Results showed that the inclusion of flexible-fixed plates in the channel enhanced the flow unsteadiness and turbulence levels, leading to Nusselt number enhancement by as high as 1,16 to 1,64 times smooth channel levels. As a result, the best heat transfer augmentation was obtained with the Re=29000, D-KE, L=100mm, w=45mm, c=1mm and flexible plate.