Fundamental research for development of an advanced sail-assisted ship

Aerodynamic Performance of a New Double-Flap Wing Sail

“…In 1985, Walker wing sails with an airfoil shape were proposed by John Walker; these were first used on a 3000-ton freighter called "MV Ashington" and can provide fuel savings of 15−25% [6]. In 1991, a wind-assisted ship propulsion device (WASP) consisting of a cylinder-flap wing was developed [7], and in 2005, a new hybrid sail [8] consisting of a slat, a hard sail and a oft sail was designed for advanced sail-assisted bulk carriers. Ouchi et al [9] proposed a telescopic structure for hard sails in 2011, and in 2013, the same authors presented the "Wind Challenger" project [10], which investigated the use of wing sails for an 180,000 deadweight tonnage (DWT) bulk carrier.…”

Experimental Study of the Aerodynamics of Sail in Natural Wind

“…Good sail type can make a sail of the same size generate higher ship thrust. During initial researches, Japanese scholars M. Ueno proposed a soft-hard-combined compound sail design, which is proven able to reach a thrust coefficient of 2.46 by wind tunnel experiment researches [7]. Fujiwara T. did the research of square soft sail's aerodynamic performance by both CFD and wind tunnel test [8].…”

“…However, in terms of literatures, current simulation researches of sail's aerodynamic performance are all based on the premise of stable wind field. Previous sail test researches were basically executed in low-speed wind tunnel with even wind speed and stable wind direction and did not simulate the influence of wind field change on sail stress situations under natural wind state [7,8,9,10,11]. However, actual sail working environment is natural wind field, the wind speed is fluctuating, and can be classified into stable average wind speed and fluctuating wind speed with characteristics of zeromean stationary random process.…”