Flight Test for Paint-Riblet

Abstract

Flight tests were conducted to evaluate a paint-riblet. This study is named FINE：Flight Investigation of skiN-friction reducing Eco-coating. The paint-riblet is made from a common paint for aircrafts. The paint-riblet has fine grooves and it reduces skin friction in the turbulent boundary layer. The groove width of the paint-riblet is 100 μm, which is optimized size for flight conditions for common airlines. The paint-riblet is painted on a fuselage of an experimental aircraft in Japan Aerospace Exploration Agency. A measurement system with Pitot rake is made in order to evaluate skin friction reduction by the paint-riblet. Wind tunnel tests including high Reynolds number condition on the momentum thickness same as the flight test are conducted to investigate detailed effects of the paint-riblet. Direct numerical simulation is also conducted to investigate the flow field on the riblet. As the result, the flight data of the paint-riblet shows agreement with the drag reduction predicted by the wind tunnel test and the direct numerical simulation. This result indicates the effectiveness of the paint-riblet in the flight condition and the usefulness of the design techniques with wind tunnel and DNS in this study.