Microfiber Coating for Drag Reduction by Flocking Technology

摘要

The biomimicry of using a hair-like structure is introduced as a drag reduction coating. The hair-like structure consists of an array of microfiber that is introduced as a passive drag reduction device. An effective flow control for a transition delay or a flow attachment is expected via an interaction or counteraction of flexible fibers, compared to the existing passive methods that use a solid or rigid surface device. The effect of the microfiber coating on drag reduction over a bluff-body was experimentally investigated using a circular cylinder in a wind tunnel at Reynolds number of 6.1 × 104. A drag reduction of 32% was obtained when the microfiber coating with a length of 0.012D was located at 40° from the stagnation point. Smoke flow visualization showed that flow separation delay was induced by the microfiber coating when the drag reduction occurred.