Experimental Investigation of Flow Over Porous Surfaces for Heat Exchanger Applications

Kurzfassung

This thesis focuses on examining the connection between boundary layer flows and porous media, specifically porous metallic foams, for potential applications in heat exchangers. The objective is to comprehend the effects of boundary layers on porous surfaces, including turbulence characteristics and heat transfer rates. The analysis utilizes precise hot wire anemometry measurements to evaluate various metallic samples and identify material parameters that impact porous metallic foams. The research aims to provide insights for enhancing the use of porous metallic foams in heat exchangers. The thesis begins with a literature review that highlights the roles of porous materials in reducing noise and frictional drag. It then discusses turbulent boundary flows and the experimental setup that includes an aero-acoustic wind tunnel and boundary layer measurement equipment. Firstly, 6 metallic samples were obtained with porous properties that are specifically designed and manufactured. Next, a detailed measurement analysis of the boundary layer over porous samples at different flow speeds and positions was conducted. Subsequently, a heat plate setup is analyzed to study the variations in hot and cold boundary layers for different voltages. In the results section, a comparison of the velocity profiles obtained from various samples at different positions and velocities within the wind tunnel’s flat plate setup is examined. Turbulence spectra analysis and comparison is also done between porous samples and flat plate.