Experimental Investigation on Drag Reduction Characteristics of Riblets Considering the Flow Environment of Fuselage

The riblets surface is a passive turbulence drag reduction technology that holds promising application prospects in drag reduction for large aircraft. Currently, most research on the drag reduction characteristics of riblets is limited to medium and low Reynolds number environments with zero pressure gradient, and the effects of adverse pressure gradient on the drag reduction rate remain controversial. The inconsistency between the local flow direction on the fuselage surface and the arrangement direction of the riblets can lead to cross-flow effects. To investigate the drag reduction performance of riblets under flow conditions more representative of actual aircraft surfaces, this study establishes an adverse pressure gradient environment at moderate-to-high Reynolds numbers. Hot-wire anemometry is employed to measure the drag reduction rate of the riblet surface, and the fundamental turbulent boundary layer statistics are observed. The measurement results indicate that the adverse pressure gradient and cross-flow effects contribute positively and negatively to the drag reduction rate of the riblets, respectively, while the increase in Reynolds number in this experiment has no substantial effect. The changes in the basic statistics of the turbulent boundary layer on the surface of the riblets are consistent with existing literature.