Experimental Study of Surface Riblet Elasticity on Aerodynamic Performance

Abstract

With the increasing effects of climate change, reducing airline fuel consumption and carbon emissions is a top priority which can be achieved by reducing overall drag production on the aerodynamic body of interest. Intentional surface roughness known as riblets have proven to reduce viscous drag production substantially, most likely due to turbulent energy reduction and cross-flow momentum reduction in the boundary layer. This research experimentally explores the effects of riblet size, geometry, and elasticity on aerodynamic lift and drag. Wind tunnel tests were conducted for sphere models in the Reynolds number range of 3.6 x 10^4 to 2.2 x 10^5 and airfoil models in the Reynolds number range of 7.5 x 10^4 to 4.5 x 10^5. The experiments concluded that varying the size and geometry of the riblets produced mixed results. However, the rigid riblets consistently outperformed the flexible riblets in terms of lift generation and drag reduction. The overall "best" performer in terms of lift to drag ratio was the larger riblet (h/c = 0.0125) with a scalloped shape and a high modulus of elasticity (more rigid). With this newfound information, riblet applications can further be optimized to maximize lift and reduce drag across the airline industry.