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Analysis of the efficiency of wind-assisted ship propulsion systems
Published in C. Guedes Soares, T.A. Santos, Trends in Maritime Technology and Engineering Volume 1, 2022
A number of publications, e.g. (Chou T. et al., 2021), contain comprehensive reviews of all aspects of WASP: potential of wind to increase ship efficiency and reduce emissions, fuel prices, policy and regulatory framework of wind technologies developments, market opportunities, engineering and transportation aspects. A long-list of studied WASP technologies comprises: traditional sail, DynaRig, Flettner rotor, kite, wingsail, turbo sail, wind turbine.
The Concept of “Green Ship”: New Developments and Technologies
Published in Adam Weintrit, Tomasz Neumann, Safety of Sea Transportation, 2017
E. Qakır, C. Sevgili, R. Fışkın, A.Y. Kaya
Wind-assist propulsion technologies has been one of most invested industry last decade because of the potentially offering double-digit fuel savings (MARAD, 2016). Wind-assisted propulsion is the use of a device, such as a wingsail, soft sail, and kite or Flettner rotor, to capture the energy of the wind and generate forward thrust (LR, 2016). Each sail type has advantages and disadvantages based on many factors such as impact on operation, performance, flexibility and installation cost etc. and they provide different fuel-savings capacity (MARAD, 2016). This difference is due not only to the varied technology types, but also to the different options for implementation and the impact of operational factors such as weather conditions and the ship’s route (LR, 2015). Among the wind-assist propulsion devices, Kite is the most efficient and advantageous sail technology (MARAD, 2016). Kite attached to the bow of the ship operate at altitude to maximize wind speeds as shown in Figure 8. According to study of Naajen & Koster (2008), by using Kite of 500 m2 attached to a 300 m towing line at Beaufort 7 with stem quartering wind can yield up to 50% fuel savings for 50.000 dwt tanker theoretically. On the other hand, applicability restrictions due to ship structures, high installing and maintenance cost and unpredictable effect on ship stability are the main disadvantages of wind-assisted propulsion systems (ABS, 2013).
Ship energy performance study of three wind-assisted ship propulsion technologies including a parametric study of the Flettner rotor technology
Published in Ships and Offshore Structures, 2020
The profile of a wingsail, especially the thickness of the aerofoil shape, is able to generate a strong lift effect and provide a strong propulsive force while decreasing the induced drag that slows down the speed of a ship. Its operating principle is to maximise the aerodynamic lift force by rotating to the optimum angle of wind attack, which is quite similar to that of an aerofoil. As the mast can rotate 360 degrees, the wingsail works in different wind angles, even upwind and be able to manoeuvre gently and safely. The WindShip project (Rosander and Bloch 2000) proposed a new rigid wingsail concept. A 50000 DWT Product Carrier was selected as the case ship, and a velocity prediction programme (VPP) was developed to predict the speed, the drift and rudder angles for given wind directions, wind speeds and propeller loadings. Within some strong windy areas, compared to an equal-sized conventional Product Carrier, around 10% fuel savings was achieved by using the wingsail technology. However, it has also been noticed that the fuel savings could be marginal at high average voyage speed within less windy area. In the Wind Challenger project (Ouchi et al. 2013), another concept of wingsail was studied for the 180000 DWT Bulk Carrier UT Wind Challenger, see Figure 2. An energy prediction programme (EPP) was developed to predict the operational performance. On the voyage between Yokohama (Japan) and Seattle (US) up to 22% fuel savings were calculated under constant speed. Viola et al. (2015) proposed a wingsail concept for the KVLCCM hull. Based on CFD simulations of aerodynamic forces and moments, under certain ship and wind speeds, approximately 10% thrust requirement from main engine was reduced by using the proposed wingsails.