Search Results (16)

The maritime industry is going through a technology transition, aiming to have carbon-neutral propulsion systems. A significant trend of orders for ships with alternative propulsion has been observed. A favorable means to meet the decarbonization requirements imposed by IMO (International Maritime Organization) is to operate vessels with sustainable energy. Harvesting wind power and its conversion into ship propulsion are gaining popularity due to emission reductions and expected reductions in fuel consumption. This paper reviews recent studies on wind-assisted propulsion systems (WAPSs), the different aspects of using sail applications in the maritime industry, and the types of wind-assisted propulsion systems. The study also presents the latest developments in WAPS systems offered by leading maritime market manufacturers and their applications on existing vessels. The article is based on a literature review (peer-reviewed articles), the information provided by wind propulsion systems manufacturers and internet research. Full article

International regulations and market demand for zero-emission transportation are accelerating the adoption of sustainable solutions in the shipping industry. Wind-Assisted Propulsion Systems (WAPSs) present a promising alternative, as elaborated on in the EU-funded Orcelle Wind project. This paper deals with the integration of wing sails into the conceptual design of a Very Large Crude Carrier (VLCC) using a parametric, multi-objective optimization framework. The results reveal that optimized VLCC designs with WAPSs can achieve over 20% reductions in fuel consumption and greenhouse gas emissions compared to conventional designs. Additionally, the obtained optimized designs exhibit notable differences in the main design characteristics and hull form compared to conventional designs, highlighting the importance of multi-objective optimization in the early design stage to tap the potential of WAPS technologies and wind propulsion. Full article

As part of the strategy to achieve net-zero Greenhouse Gas (GHG) emissions in international maritime shipping, there is ongoing exploration into the use of wind propulsion systems as auxiliary ship propulsion devices. When considering a rigid sail as the wind propulsion system, evaluating the performance of a single sail is relatively simple. However, assessing the performance of multiple sails is more challenging due to the interference between the sails and between the sails and the hull. In this study, the thrust characteristics of two rigid sails attached to a ship are investigated by using Computational Fluid Dynamics (CFD). This includes considering the interference effects between the sails themselves and between the sails and the hull. The research reveals the innovative optimized angle of attack for maximizing thrust under tailwind conditions. At 150° in relative wind direction, the best performance is achieved with a low angle of attack on the fore side sail and a high angle of attack on the aft side sail. At 180° in relative wind direction, a high angle of attack on the fore side sail and a low angle of attack on the aft side sail yield the best results. Here, a “low” angle of attack means that the lift force is greater than the drag force, while a “high” angle of attack means the drag force is greater than the lift force. In this study, the force in the ship’s forward direction is only focused on optimizing the angles of attack of the two sails. However, the side forces caused by the sails are also significant for the ship’s sailing conditions. Therefore, future work will involve optimizing the angles of attack under drifting conditions. Full article

The utilization of unmanned sailboats as a burgeoning instrument for ocean exploration and monitoring is steadily rising. In this study, a dual sail configuration is put forth to augment the sailboats’ proficiency in its wind-catching ability and adapt to the harsh environment of the sea. This proposition is based on a thorough investigation of sail aerodynamics. The symmetric rigid wing sails NACA 0020 and NACA 0016 are selected for use as the mainsail and trailing wing sail, respectively, after considering the operational environment of unmanned sailboats. The wing sail structure is modeled using SolidWorks, and computational fluid dynamics (CFD) simulations are conducted using ANSYS Fluent 2022R1 software to evaluate the aerodynamic performance of the sails. Key aerodynamic parameters, including lift, drag, lift coefficient, drag coefficient, and thrust coefficient, are obtained under different angles of attack. Furthermore, the effects of mainsail aspect ratios, mainsail taper ratios, and the positional relationship between the mainsail and trailing sail on performance are analyzed to determine the optimal structure. The thrust provided by the sail to the boat is mainly generated by the decomposition of lift, and the lift coefficient is used to measure the efficiency of an object in generating lift in the air. The proposed sail structure demonstrates a 37.1% improvement in the peak lift coefficient compared to traditional flexible sails and exhibits strong propulsion capability, indicating its potential for widespread application in the marine field. Full article

This study aimed to enhance the stability and response speed of a passive stabilized double-wing flapping micro air vehicle (FMAV) by implementing a feedback-controlled biomimetic tail. A model for flapping wings accurately calculated the lift force with only a 2.4% error compared to the experimental data. Experimental tests established the relationship between control torque and tail area, swing angle, and wing–tail spacing. A stability model for the double-wing FMAV was developed, incorporating stabilizing sails. Linearization of the hovering state facilitated the design of a simulation controller to improve response speed. By adjusting the feedback loops of velocity, angle, and angular velocity, the tail controller reduced the angle simulation response time from 4 s to 0.1 s and the velocity response time from 5.64 s to 0.1 s. In take-off experiments, a passive stabilized prototype with an adjustable tail angle exhibited enhanced flight stability compared to fixed tails, reducing standard deviation by 72.96% at a 0° take-off angle and 56.85% at a 5° take-off angle. The control axis standard deviation decreased by 38.06% compared to the passive stability axis, confirming the effectiveness of the designed tail angle controller in reducing angular deflection and improving flight stability. Full article

Water–air trans-media unmanned vehicle is a kind of aircraft, which can freely fly in the air, sail in the water and pass through free surface. For trans-media aircrafts, the development process from air–surface to air–underwater and from submarine-launched drive to autonomous drive is investigated. By analyzing the characteristic of manta ray, flying fish and existing aircraft, this paper proposes a new water–air trans-media unmanned vehicle with flat dish-airfoil-shaped main body and telescopic NACA-type wing. Then the numerical method to calculate the lift and drag forces is established and validated by the results of classic NACA cases. On this basis, the flow field around the new vehicle is numerically simulated, and its lift–drag performances in different media (air and water) and ground effect are analyzed, comparing it with a model inspired by the Blackwing Unmanned Aerial Vehicle (UAV). The findings illustrate the superior performance of the new vehicle in terms of lift and drag forces, offering an innovative design framework for water–air trans-media UAV applications. Full article

With the increasing popularity of yachting sports and races comes the need to develop a more advanced and efficient propulsion device. Significant improvement can be made when using a mainly lift-driven propulsion source, known as a wing sail. This idea, dating back as far as the mid-70s, is nowadays regaining interest as a propulsion system in multihull, high-performance racing vessels (for instance, the AC50 and AC72 America’s Cup yacht classes). This article documents 2D and 3D numerical analyses of wing sail systems imitating those of an AC72 racing yacht class. It depicts methods employed in two- and three-dimensional steady-state flow simulations, compares systems equipped with various geometries of mainsails, and details a comprehensive examination of the airflow around the vessel using spatial analyses. Numerical calculations were carried out using ANSYS CFX and ANSYS Fluent (with overset feature) for 2D and 3D models, respectively. All simulations were conducted under conditions similar to those acting on the real system, i.e., high Reynolds number (order of magnitude 10⁶ to 10⁷) and atmospheric boundary layer (in the 3D model). Full article

Sail-assisted technology can reduce greenhouse-gas emissions by saving the energy consumption of ships with wind energy utilization. The distribution characteristics of marine wind resources are critical to the energy-saving effect of sail-assisted ships. However, due to the lack of effective energy-saving evaluation methods for improving the utilization rate of wind energy, a high potential for wind energy utilization still exists. A novel energy-saving evaluation method based on the wind energy resource analysis of typical ship routes is proposed in this paper. First, a three-degree-of-freedom motion model for sail-assisted ships considering the wing sail forces is constructed. Then, a wind resource acquisition and analysis method based on spatial–temporal interpolation is proposed. On this basis, the wind field probability matrix and wing sail force matrix are established. Ultimately, an energy-saving evaluation method for sail-assisted ships on typical routes is proposed by combining the sailing condition of ships. The case study results show that the energy-saving effect of a wing sail-assisted oil tanker that sailed on the China-to-Middle East route was more than 5.37% in 2021 and could reach 9.54% in a single voyage. It is of great significance to realize the popularization and application of sail-assisted technology, thus improving the greenization of the shipping industry. Full article

Wing-sailed autonomous sailing monohulls are promising platforms used in various scenarios to provide data for marine science research. These platforms need to operate long-term in changing seas; their general configurations (size matching between sail, hull, and keel) necessitate careful trade-offs to balance safety and efficiency. Since autonomous sailboats are often designed for different observation missions, scientific pay-loads and target areas, their design space is considerably large. It is also challenging to obtain prior performance estimation from historical designs. Therefore, traditional offline surrogate-based simulation-driven design frameworks suffer from a large amount of sampling required, the computational cost of which remains too expensive for such ad hoc design tasks. This paper proposes an innovative, generalised simulation-driven framework combining Bayesian optimisation and knowledge transfer. It allows for high-quality, low-cost optimisation of autonomous sailing monohulls’ general configuration without initial design and prior performance estimation. The proposed optimisation framework has been used to optimise the ‘Seagull’ prototype within the design constraints. The optimised design exhibits significant performance improvements. At the same time, the results show that the present method is significantly superior to traditional offline methods. The authors believe that the proposed framework promises to provide the autonomous sailing community with a solution for a general design methodology. Full article

Similar to parafoils, ram-air kites are flexible membrane wings inflated by the apparent wind and supported by a bridle line system. A major challenge in estimating the performance of these wings using a computer model is the strong coupling between the airflow around the wing and the deformation of the membrane structure. In this paper, we introduce a staggered coupling scheme combining a structural finite element solver using a dynamic relaxation technique with a potential flow solver. The developed method proved numerically stable for determining the equilibrium shape of the wing under aerodynamic load and is thus suitable for performance measurement and load estimation. The method was validated with flight data provided by SkySails Power. Measured forces on the tether and steering belt of the robotic kite control pod showed good resemblance with the simulation results. As expected for a potential flow solver, the kite’s glide ratio was overestimated by 10–15%, and the measured tether elevation angle in a neutral flight scenario matched the simulations within 2 degrees. Based on the obtained results, it can be concluded that the proposed aero-structural model can be used for initial designs of ram-air kites with application to airborne wind energy. Full article

Wing-assisted technology is an effective way to reduce emissions and promote the decarbonization of the shipping industry. The lifting and lowering of wing-sail is usually driven by hydraulic system. Leakage, as an important failure form, directly affects the safety as well as the functioning of hydraulic system. To increase the system reliability and improve the wing-assisted effect, it is essential to conduct leakage fault diagnosis of lifting and lowering hydraulic system. In this paper, an AMESim simulation model of lifting and lowering hydraulic system of a Very Large Crude Carrier (VLCC) is established to analyze the operation characteristics of the hydraulic system. The effectiveness of the model is verified by the operation data of the actual hydraulic system. On this basis, a wavelet packet transform (WPT)-based sensitive feature extracting method of leakage fault for the hydraulic system is proposed. Subsequently, a support vector machine (SVM)-based multi-classification model and diagnosis method of leakage fault are proposed. The study results show that the proposed method has an accuracy of as high as 97.5% for six leakage fault modes. It is of great significance for ensuring the reliability of the wing-sail operation and improving the utilization rate of the offshore wind resources. Full article

The sailing efficiency of an underwater glider, an important type of marine environment detection and data collection equipment, directly affects its range and duration. The zero-angle-of-attack gliding can be achieved by adjusting the wing installation angle to minimize the drag and improve the sailing efficiency, and thus further improving performance of the glider. This paper first presents the dynamic characteristics of a hybrid-driven underwater glider with a certain wing installation angle when it is sailing at zero angle of attack in buoyancy-driven mode and hybrid-driven mode. In buoyancy-driven mode, with a given wing installation angle, the glider can achieve zero-angle-of-attack gliding only at a specific glide angle. In hybrid-driven mode, due to the use of a propulsion system, the specific glide angle that allows the zero-angle-of-attack gliding in buoyancy-driven mode is expanded to a glide angle range bounded by zero degrees. Then, the energy consumption per meter is introduced as an indicator of sailing efficiency, and the effects of glide angle and wing installation angle on sailing efficiency of the zero-angle-of-attack glider in two driving modes are studied under the conditions of given net buoyancy and given speed, respectively. Accordingly, the optimal wing installation angle for maximizing the sailing efficiency is proposed. Theoretical analysis shows that the sailing efficiency of a zero-angle-of-attack glider can be higher than that of a traditional glider. Considering the requirements of different measurement tasks, a higher sailing efficiency can be achieved by setting reasonable parameters and selecting the appropriate driving mode. Full article

This work demonstrates the advantages of using laser powder bed fusion for producing a rudder bulb of a moth class sailing racing boat via laser powder bed fusion (LPBF). The component was designed to reduce weight using an AlSi7Mg0.6 alloy and incorporated a biomimetic surface texture for drag reduction. For the topological optimization, the component was loaded structurally due to foil wing’s lift action as well as from the environment due to hydrodynamic resistance. The aim was to minimize core mass while preserving stiffness and the second to benefit from drag reduction capability in terms of passive surface behavior. The external surface texture is inspired by scales of the European sea bass. Both these features were embedded to the component and produced by LPBF in a single run, with the required resolution. Drag reduction was estimated in the order of 1% for free stream velocity of 2.5 m s⁻¹. The production of the final part resulted in limited geometrical error with respect to scales 3D model, with the desired mechanical properties. A reduction in weight of approximately 58% with respect to original full solid model from 452 to 190 g was achieved thanks to core topology optimization. Sandblasting was adopted as finishing technique since it was able to improve surface quality while preserving fish scale geometries. The feasibility of producing the biomimetic surfaces and the weight reduction were validated with the produced full-sized component. Full article

Autonomous land yachts can play a major role in the context of environmental monitoring, namely, in open, flat, windy regions, such as iced planes or sandy shorelines. This work addresses the design, modeling, and simulation of a land yacht probe equipped with a rigid free-rotating wing sail and tail flap. The wing was designed with a symmetrical airfoil and dimensions to provide the necessary thrust to displace the vehicle. Specifically, it proposes a novel design and simulation method for free rotating wing sail autonomous land yachts. The simulation relies on the Gazebo simulator together with the Robotic Operating System (ROS) middleware. It uses a modified Gazebo aerodynamics plugin to generate the lift and drag forces and the yawing moment, two newly created plugins, one to act as a wind sensor and the other to set the wing flap angular position, and the 3D model of the land yacht created with Fusion 360. The wing sail aligns automatically to the wind direction and can be set to any given angle of attack, stabilizing after a few seconds. Finally, the obtained polar diagram characterizes the expected sailing performance of the land yacht. The described method can be adopted to evaluate different wing sail configurations, as well as control techniques, for autonomous land yachts. Full article

Shape memory alloys (SMAs) show a particular behavior that is the ability to recuperate the original shape while heating above specific critical temperatures (shape memory effect) or to withstand high deformations recoverable while unloading (pseudoelasticity). In many cases the SMAs play the actuator’s role. Starting from the origin of the shape memory effect, the mechanical properties of these alloys are illustrated. This paper presents a review of SMAs applications in the aerospace field with particular emphasis on morphing wings (experimental and modeling), tailoring of the orientation and inlet geometry of many propulsion system, variable geometry chevron for thrust and noise optimization, and more in general reduction of power consumption. Space applications are described too: to isolate the micro-vibrations, for low-shock release devices and self-deployable solar sails. Novel configurations and devices are highlighted too. Full article