Effects of surface texture on flow in channels

• Main Author: Lim, Sherman Zheng Rui
• Other Authors: Chan Weng Kong
• Format: Final Year Project
• Language: English
• Published: 2017
• Subjects: DRNTU::Engineering::Mechanical engineering
• Online Access: http://hdl.handle.net/10356/72012
• Institution: Nanyang Technological University

Friction is a resistive force experienced in everyday activities due to the relative motion of two matters. It can be favorable or disadvantageous depending on the application. In many engineering applications such as fluid flow in pipes, friction is proven to be disadvantageous due to the loss of energy and thus a reduction in efficiency. As a result, many studies have been done to reduce the frictional drag experienced when fluid flows through pipes. By altering the surface structure appropriately, the interaction between the fluid and solid surface can be modified such that the adhesion is decreased which reduces the frictional drag experienced. Studies have shown that by treating the surface of polytetrafluoroethylene, also known as Teflon, with sandpaper, frictional drag can be reduced. However, in the studies done, there lacked one which compares the effect of directional sanding on specimens treated with 2 grit designations of sandpapers. Thus, this experimental study aims to investigate the effect of surface texture by measuring the frictional drag. The frictional drag was measured by measuring the pressure drop across the specimen while keeping all other variables constant. A total of 19 specimens, including one control, were created by treating the Teflon specimens with different grit designations of sandpapers in different sanding protocols – in the flow direction and in a random motion. The results obtained from the contact angle measurements and pressure drop consistently showed that the specimens treated with both the 80 and 220 grit sandpapers achieved the best results. In addition, it can also be observed that the specimens treated in a random motion produced better results. To add on to that, the results and images obtained from the surface roughness profile and Scanning Electron Microscope respectively concurred with the above results.