Advances in Riblets Design

Abstract

Continuous evolution in nature has created optimum solutions for creature survival that have inspired many innovative engineering designs. Riblet geometries, passive flow control devices, have been studied, which were inspired by the skin of fast-swimming sharks. Turbulent boundary layer research reveals the positive effect of riblets in reducing drag by manipulating turbulent structures. Reducing drag is an important topic for the aviation industry, as it directly relates to fuel savings and reductions in carbon footprints. Aircraft noise represents another significant area of concern. When riblet designs modify turbulent structures, they can also impact pressure sources within the boundary layer, consequently influencing the generation of self-noise. Earlier research studies have demonstrated the favorable outcomes of riblet configurations on the variations in wall pressure, resulting in reduced levels of noise propagation. The current review paper is mainly devoted to the application of riblets in the aviation industry, focusing on studies that are performed in wind tunnels, flight tests, and using numerical techniques. Proving the desired performance of micro-grooves, their method of fabrication and implementation on aircraft surfaces are important topics that are also discussed. In addition, the effect of durability on the performance and required maintenance intervals was previously investigated and is also presented. Finally, recommendations for future activities in the relevant fields of study are provided.