Environmental concerns are influencing a greater need for renewable and sustainable energy across the world with specialist technologies being at the forefront of new designs and solutions. As maritime industries begin to tackle the climate change issues, ports and shipping companies are looking for carbon-free alternatives by testing potential solutions for vessels. The requirement to make a move toward greener shipping is imminent. As companies start to concentrate their efforts in developing efficient solutions for improving performance and reducing emissions, Cape Horn Engineering are applying their skills and expertise to support and contribute to the design of these advancements.
The U.K.-based firm is an independent computational fluid dynamics (CFD) consultancy specializing in performance prediction of cargo ships, renewable energy structures, racing sailing yachts, superyachts, motor boats and more.
Using specialist CFD technology
CFD technology has become a crucial support for naval architects, yacht designers and design engineers to optimize designs for critical elements such as weight saving, performance predictions, reducing emissions and design optimization.
Cape Horn Engineering has been at the core of simulation-based America’s Cup and Ocean Racing design campaigns for over 15 years, always pushing the boundaries. Similarly, they have vast experience in ship hydrodynamics, having been involved in yacht and ship design using CFD for the last two decades. They specialize in high-fidelity RANS-based simulation techniques where accurate forces and moments are obtained for the given shape candidates and operating conditions. For all simulations, Cape Horn Engineering use the Star-ccm+ commercial software package from Siemens PLM and have access to a large high performance computing cluster on the Cloud.
Their CFD methods cover a large variety of flow behaviors and includes free-surface flow, viscous flow, full-scale performance prediction, fluid-structure-interaction and dynamic behavior. They can help win yacht races, improve performance, safety or passenger comfort, reduce emissions and save on fuel.
Wind Propulsion Technology (WPT)
Wind Propulsion Technology (WPT) has been evaluated to address environmental problems within global commercial shipping. According to some recent studies, wind-assisted ship propulsion using rigid wings, sails, kites, Magnus rotors or other novel devices on some specific vessel types such as bulk carriers and tankers, have the potential of fuel savings and emission reductions around 10%-30%. The International Maritime Organization (IMO) recently acknowledged wind propulsion as one of the solutions for the shipping industry to meet decarbonization targets.
Due to their renowned experience and specialist technology, Cape Horn Engineering are able to offer a holistic analysis of the benefits of WPT. The firm is supporting one of its clients Windship Technology Ltd for a solid wing power concept that is being developed by a consortium of key players in the global shipping industry, which could revolutionize the way tomorrow’s vessels carry goods across the world’s oceans. The patented U.K.-designed Windship rig system is engineered to help reduce fuel and emissions, which will materially help the shipping industry move closer toward achieving its emissions reduction targets.
Dr.-Ing Rodrigo Azcueta, Managing Director of Cape Horn Engineering, said the company is running a CFD program to further improve the design of the solid wings. “One of the key focuses of our project is to provide a clearer, unbiased and more detailed analysis of the new technologies available,” he said. “This allows interested parties to be confident in the investment of greener technology. The analytical evidence provided will give businesses a clearer understanding of the potential savings that can be realized with the implementation of the green propulsion systems. Without significant mitigating action it is projected that the global shipping industry could account for almost a fifth of carbon emissions by 2050.”
In order for the shipping industry to adopt these new technologies, the accurate analysis of the potential savings and the results must be presented to all stakeholders involved. To achieve this, improved simulation techniques are needed to optimize design and routing. Several factors need to be accounted for, including the aerodynamics of the thrust producing devices, the vessel hydrodynamics, propellers and engine types and the optimal routing.
Cape Horn Engineering were commissioned to run an extensive CFD program to further improve the design of the solid wings. A multitude of wing assembly shape configurations were analysed in varying wind conditions. In total, almost 1,000 high-fidelity CFD simulations were performed and analyzed. The simulations were used to set up force models needed to describe the vessel’s hydrodynamic and aerodynamic behavior. Operating conditions for the WPT devices are apparent wind angle and speed, wind shear and wind gradient (variation of wind speed and direction with height above the water surface), and angle of attack of the wings and its flaps.
A two digit percentage improvement in the aerodynamic performance of the wing assembly was obtained. Some selected simulation points were compared and validated with the wind tunnel testing, as well as with previous CFD analysis provided by Lloyd’s Register. Experts from the Wolfson Unit (University of Southampton) were also involved in the analysis of the CFD results. Extreme wind load cases were delivered to structural experts for assuring optimum weight and safety of the structures.
Further CFD design optimization in 2020 will take the Windship concept ship into consideration as a whole, including the ship hydrodynamics, engine and propulsion, aerodynamics and optimal routing. The operating conditions for the vessel will be the advance speed and the drift, heel and rudder angles. Furthermore, windage on superstructures and the added resistance due to sea state will be modeled and taken into account.
“When it comes to building a new ship, the design must be optimized to fit the wings on deck efficiently from both an operational and performance perspective. The design of hull features such as skegs or bilge keels might be required to balance the transversal instability induced by the installation of the WPT,” Azcueta said. “Having a CFD model comprising of both the hydrodynamic and aerodynamic artifacts of the design will allow highly targeted design optimizations. Currently, wind propulsion systems and ship design are considered as two entities, hence they are designed independently. It is reasonable to believe that they should be designed as a whole from the earliest stage, due to the dependency of each aspect on the other. The optimization process and predicted potential performance will determine the optimal operational points resulting in the lowest required engine power, fuel consumption and total emissions. The aim of our project is to facilitate the uptake of WPT’s. Moreover, we hope to enable the implementation of these technologies in the shortest time frame possible.”
(Image: Cape Horn Engineering)