Turbulent Drag Reduction : Effect of Implanted Fiber

Abstract

In the present paper, drag reduction in turbulent pipe flow of water by means of implanting microfibers, instead of injecting or premixing them, has been investigated. Experiments using FRP pipes with microfibers implanted on the inside wall have been conducted at various Reynolds numbers (2000-40000), as well as with various types of microfibers. A maximum drag reduction of about 50% has been obtained using one type of microfiber, and the most effective length of microfibers in terms of the law governig the wall variables has been determined to be 6-8 wall units. The direction of implanted microfibers also was found to have an effect on the drag reduction of pipe flow.