Frictional Drag Reduction with Air Lubricant over Super-Water-Repellent Surface

Abstract

This paper presents a new technique for reducing frictional drag using a super-water-repellent surface and air- injection (called an SWR & A technique). Its effectiveness was examined by carrying out pressure-loss measurements with a tube of rectangular cross section, along with resistance tests on a horizontal flat plate, a 7.2-m-long tanker model, and a 12-m-long high length-to-beam-ratio model ship. These test results showed that the new technique can significantly reduce the models’ frictional drag; for example, the frictional resis- tance on the SWR surface was reduced by 80% at a speed of 4m/s and 55% at 8m/s.