Ship energy performance study of three wind-assisted ship propulsion technologies including a parametric study of the Flettner rotor technology

Due to the call of low carbon emissions and requirement of energy efficient shipping, the utilization of wind-assisted ship propulsion (WASP) technologies has become a popular topic in shipping activities. Ship owners and operators call for investigations on the performance of using different WASP technologies for commercial ships in real life operational conditions. In this study, a 4 degrees of freedom ship performance prediction model is used to compare three WASP technologies: the Flettner rotor, a wingsail and the DynaRig concept. An Aframax Oil Tanker on a route between Gabon and Canada is used in a case study to compare the three WASP technologies using actual information for the voyage (e.g. route, environment conditions). The fuel savings for the three technologies were calculated and they varied between 5.6% and 8.9%, where the Flettner rotor showed the largest fuel savings. A parametric study of the Flettner rotor technology was carried out to research how its dimensions and operation conditions for two ship types on two voyages influence the fuel savings. The results show that fuel savings were achieved by several percentages for all the studied cases. It is shown that it is necessary to select and operate the Flettner rotor according to its ship type, speed, voyage routes and corresponding weather conditions to achieve as large fuel savings as possible

Wind-assisted, electric, and pure wind propulsion - the path towards zero-emission RoRo ships

Electrical and wind propulsion, together with energy stored in batteries and renewable energies harnessed onboard, can lead the way towards zero-emission ships. This study compares wind propulsion solutions and battery storage possibilities for a RoRo ship operating in the Baltic Sea. The ship energy systems simulation model ShipCLEAN is used to predict the performance of the zero-emission ship in real-life operating conditions. The study showcases how ships can be transferred from a conventional, diesel-powered to a zero-emission ship. For the zero-emission ship, all energy needed for auxiliaries and propulsion is taken from renewable sources onboard or from batteries. Challenges and opportunities, as well as necessary adaptions of the route and logistics, are discussed. Results of the study present which wind propulsion technology is the most suitable for the example RoRo ship, and how the installation of suitably sized battery packs for zero-emission operation affects the cargo capacity of the ship

Design, operation and analysis of wind-assisted cargo ships

This study presents a novel approach to analytically capture aero- and hydrodynamic interaction effects on wind-assisted ships. Low aspect ratio wing theory is applied and modified to be used for the prediction of lift and drag forces of hulls sailing at drift angles. Aerodynamic interaction effects are captured by analytically solving the Navier-Stokes equation for incompressible, potential flow. The developed methods are implemented to a 4 degrees-of-freedom performance prediction model called “ShipCLEAN”, including a newly developed method for rpm control of Flettner rotors on a ship to maximize fuel savings. The accuracy of the model is proven by model- and full-scale verification. To present the variability of the model, two case study ships, a tanker and a RoRo, are equipped with a\ua0total of 11 different arrangements of Flettner rotors. The fuel savings and payback times are assessed using realistic weather from ships traveling on a Pacific Ocean route (tanker) and Baltic Sea route (RoRo). The results verify the importance of using a 4 degrees-of-freedom ship performance model, aero- and hydrodynamic interaction and the importance of controlling the rpm of each rotor individually. Fuel savings of 30% are achieved for the tanker,\ua0and 14% are achieved for the RoRo

Retrofitting WASP to a RoPax vessel—design, performance and uncertainties

Wind-assisted propulsion (WASP) is one of the most promising ship propulsion alternatives\ua0that radically reduce greenhouse gas emissions and are available today. Using the example of a\ua0RoPax ferry, this study presents the performance potential of WASP systems under realistic weather\ua0conditions. Different design alternatives and system layouts are discussed. Further, uncertainties in\ua0the performance prediction ofWASP systems are analyzed. Included in the analysis are the sail forces\ua0as well as the aero- and hydrodynamic interaction effects, i.e., the sail–sail and sail–deck interaction as\ua0well as the drift and yaw of the ship. As a result, this study provides guidelines on the most important\ua0parameters when designing and modeling aWASP ship. Finally, the study presents an analysis of the\ua0expected accuracy of the employed empirical/analytical performance prediction model ShipCLEAN

A method for risk analysis of ship collisions with stationary infrastructure using AIS data and a ship manoeuvring simulator

The study presents a methodology that uses AIS data and a ship manoeuvring simulator to simulate and analyse marine traffic schemes with regard to risks for accidents. An event identification method is presented, which is needed for the accident scenario part of the methodology. This is based on AIS data, where the Great Belt VTS area was used to verify the methodology. Three events that could result in ship-bridge allisions were modelled and simulated in the simulator: drifting ship, sharp turning ship and miss of turning point. The Monte Carlo method was used to perform large number of simulator runs, including a parameter sensitivity analysis. The probability of a ship allision against the Great Belt Bridge was calculated to be 0.007. Analysis of the ship-bridge allision cases was shown to be dominated by the event drifting ship. This event has a relatively low kinetic energy at the impact, and the expected allision energy for a 1,000-year allision corresponds to a 178 m tanker with 57,870 DWT and ship speed 14.6 knots. Finally, this study presents a mitigation analysis, which shows how the probability of allisions can be reduced by reducing the ship speed or altering the traffic separation scheme

A voyage planning tool for ships sailing between Europe and Asia via the Arctic

The Arctic is rapidly transforming into a navigable ocean because of global warming reducing the extent of sea ice. As a consequence, a large percentage of the sailing distance between Europe and Asia could be saved by alternatively sailing through the Arctic rather than the traditional route via the Suez Canal. However, taking Arctic routes is fraught with risks and additional costs due to sea ice. The major purpose of this study is to develop a voyage planning tool to improve the safety and fuel efficiency of commercial ships sailing between Europe and Asia via the Arctic, which is achieved by voyage optimization through frequently updated meteorological, oceanographic and ice forecasting. This tool is characterized by route planning for the entire voyage, inclusive of the Arctic passage and the open water legs in Asia and Europe. A single-objective optimization for minimizing fuel consumption under various environmental and operational conditions is established. The resistance model accounts for both ice thickness and ice concentration of unconsolidated Arctic sea ice in the summer. Ice related risks defined in the Polar Operational Limit Assessment Risk Indexing System (POLARIS) are dealt as constraint. Other constraints such as avoidance of land and shallow water are also included. These functions are demonstrated by the two case study vessels sailing between Rotterdam and Shanghai via both the Arctic and the traditional routes

Unsteady RANS and IDDES studies on a telescopic crescent-shaped wingsail

Over the years, several research projects have evaluated different concepts for wind-assisted propulsion, generally concluding that it can lead to significant fuel savings. The time-averaged propulsive performance of a single rigid wingsail has been analysed in previous studies. However, the unsteady characteristics of the external loads which may induce structural vibration are also important to be considered. In this study, full-scale simulations, with both unsteady RANS and IDDES methods, are performed to analyze the flow field. The paper\u27s analysis includes flow separation and vortex shedding, the development and dissipation of wake vortices, and the lift reduction due to tip vortices. It also studies the telescopic function of the wingsail by analyzing sails with different heights and wind conditions. The paper concludes that the unsteady RANS and IDDES simulations make similar predictions for time-averaged loads but disagree on the unsteady characteristics. The IDDES simulations indicate more complex vortex-shedding phenomena

Methodology for the simulation of a ship’s damage stability and ultimate strength conditions following a collision

This paper presents a methodology called SHARC developed for the simulation and analysis of a ship’s damage stability and ULS conditions following a collision. SHARC combines three types of methods: advanced nonlinear finite element simulations that simulate the collision scenario, a dynamic damage stability simulation tool called SIMCAP, and a modified Smith method for the ULS analysis of a collision-damaged ship structure. The novelty of the presented methodology is that it can be used for real-time simulations to study the ingress of water through the damage opening of a struck vessel and how it affects the ship’s stability, structural integrity (ULS) and survival capability against, e.g., capsizing. The results for an intact and a damaged oil tanker under noncorroded and corroded structural conditions and various sea states are presented to demonstrate the features of SHARC

Development of a ship performance model for power estimation of inland waterway vessels

A ship performance model is an important factor in energy-efficient navigation. It formulates a speed–power relationship that can be used to adjust the engine loads for dynamic energy optimisation. However, currently available models have been developed for sea-going vessels, where the environmental conditions are significantly different from those experienced on inland waterways. Inland waterway shipping has great potential to become a mode of transport that can both improve safety and reduce emissions. Therefore, this paper presents the development of an energy performance model specifically for inland waterway vessels (IWVs). The holistic ship energy system model is based on empirical methods, from resistance to engine performance prediction, established in a modular code architecture. The resistance and propulsion prediction in confined waterways are captured by a newly developed method, considering a superposing of shallow water and bank effect. Verification against model tests and high-fidelity simulations indicate that the selected empirical methods achieved good accuracy for predicting ship performance. The resistance prediction error was 5.2% for single vessels and 8% for pusher-barge convoys based on empirical methods. The results of a case study investigating the performance of a self-propelled vessel under dynamic waterway data, indicate that the developed model could be used for onboard power monitoring and energy optimisation during operation

A comparison of ship manoeuvrability models to approximate ship navigation trajectories

It is essential to describe a ship’s manoeuvrability for various applications, e.g. optimal control of unmanned\ua0surface vehicles (USVs). In this study, the capability of two recognised manoeuvrability models to predict\ua0ships’ trajectories is investigated based on both simulation and open-water experiment test data. The\ua0parameters of these models are estimated by a statistical learning method. The goodness of the two\ua0estimated models for describing a merchant ship’s manoeuvrability is first studied using her\ua0manoeuvring simulation data. Then, experimental manoeuvring tests to use a USV in open water with\ua0wind and drifting effects are used to check the conventional model identification procedures. Finally,\ua0some modifications and adjustments are proposed to improve the conventional procedures. It shows\ua0that the proposed procedures can accurately derive the ship’s manoeuvrability based on experimental data