Experimental Investigation of Friction Drag Reduction in Turbulent Boundary Layers

Abstract

For large commercial airplanes, over 50% of the total drag is contributed by the turbulent skin friction. Even a small reduction of friction drag can result in significant fuel savings in the operation lifetime of a commercial airplane. Therefore, extensive effort has been made to reduce turbulent friction drag by controlling the near-wall turbulence. In this talk, several passive and active friction drag reduction methods are firstly reviewed and summarized, including riblets, in-plane and out-of-plane surface motions. Subsequently, the experimental work on friction drag reduction by passive and active means is presented. We used riblets and spanwise traveling surface waves to manipulate the flat plate boundary layers and found drag reduction of a few percent for riblets and roughly 10% for the combination of the passive and active methods.

Speaker

Dr Wenfeng LI is an Associate Professor at the School of Aeronautics of the Northwestern Polytechnical University (NPU), China. He obtained his PhD in 2017 at the Institute of Aerodynamics (AIA) of the RWTH Aachen University, Germany. After that, he worked at AIA as a Postdoctoral Researcher from 2017 to 2020 before he became an Associate Professor at NPU. Currently, Dr LI’s research interests are turbulent boundary layers, active/passive drag reduction, and measurement techniques, e.g. PIV and PTV.