SHIP DECARBONISATION & EEXI/EEDI

Investigating carbon free energy alternatives and design solutions

Cape Horn Engineering have pioneered RANSE based CFD since its very beginning and continues its research work on a daily basis. Our specialist CFD technology and expertise is at the forefront of new design solutions to enhance energy efficiency in the shipping industry. To help reduce emissions, we assist shipping companies with our specialist CFD technologies to investigate carbon-free energy alternatives and design solutions.

We also specialise in EEXI/EEDI calculations based on high-fidelity RANS CFD and offer EEXI/EEDI calculations in a very efficient and cost effective manner, having developed validated workflows and Best Practice Guidelines in conjunction with a leading classification society (Lloyds Register) by testing potential solutions for vessels.

Cape Horn Engineering is proud to provide a range of services to clients across the shipping industry. In addition to standard performance analysis, design optimisation and seakeeping analysis, Cape Horn offers a range of services that can be tailored to your specific needs. In recent years the increased demand of the industry has led to us gaining extensive experience in:

EEXI calculations

Analysis of ESD’s

Comparison and development of WASP Devices

Energy Efficiency Existing Ship Index (EEXI)

CFD offers a cost effective and fast solution to develop speed-power curves for vessels lacking data that meets the strict conditional requirements of the regulations. Cape Horn Engineering is experienced in calculating the reference speed of a vessel for EEXI, having developed an efficient workflow in conjunction with a leading classification society.

Employing CFD ensures the calculated reference speed accounts for the physical flow around the vessel, considering any modifications or ESD’s that have been installed, while avoiding the time and expense of model testing. It is considerably more accurate than the conservative empirical formulae supplied by the IMO and the higher fidelity calculation may help ensure compliance for marginal vessels.

Our CFD technology can be used to enhance the energy efficiency through three primary mechanisms:

1 – Design exploration and optimisation using a simulation-driven approach

Large parts of the workflow are automated which reduces analysis time significantly. We can run around 50 calm water simulations per day, which coupled with the fact that CFD allows for rapid geometry changes, means that several design candidates can be evaluated in a small time frame. At its lowest level this makes it very fast to compare multiple prospective design. Changes can be manually implemented by the naval architects based upon the hydro results and the new design can be quickly evaluated. It is also possible to focus on a single element of the hull. For example, the performance gains from adding a bulbous bow can be determined and then compared to a number of different bulbs. At its highest level this allows fully automated optimisations to take place. The CFD simulation can be paired with an optimisation algorithm and a parametric model in an automated loop effectively exploring the whole design space.

2 – Investigation of novel ideas and technologies implemented in a short time frame

Utilising our CFD technology removes the constraints of traditional model testing. Elaborate test rigs do not need to be devised and complicated scaling issues are no longer required as the energy saving devices can be modelled in full scale. The post processing capabilities of CFD are immense. Forces can be decomposed into the shear and pressure components, and quantified for the different surfaces. Pressure fields can be plotted and streamlines can be used to visualise the flow, allowing a far more detailed understanding of what is actually happening to be developed. Advanced visualising scenes allowing users to interact and explore the solution, viewing it from any perspective. These operations come together and form an environment in which new ideas can be tested and examined, with a very thorough understanding being developed so that they may be fully exploited.

3 – A holistic, integrated design process

4 – Validation & Verification (V&V)

Cape Horn Engineering have simulation workflows and analysis tools to efficiently perform verification and validation (V&V) of a simulation set up, in accordance with ITTC Quality Control Procedures. The process of V&V is integral to producing reliable and accurate CFD results and is something that we have always taken very seriously. These V&V procedures ensure that our CFD results meet the strict requirements of the IMO when performing EEXI simulations.

5 – Energy Saving Devices (ESD) (V&V)

Energy Saving Devices offer great potential to improve the efficiency of a ship, helping to reduce the emissions and the operational expenses. They may also be employed to help a vessel meet the EEXI requirements.

CFD offers the perfect test environment in which to model ESD’s, in full scale, as applied to the physical ship geometry. We are experienced in complex simulation set ups in which propulsion is modelled with a rotating, meshed propeller geometry as opposed to relying upon common simplifications to ensure the highest degree of accuracy. This analysis confirms that the ESD will perform as expected, and the maximum increase in efficiency is achieved prior to the costs of installation.

EEXI Simulation – White Paper

Advantages of CFD compared to tank testing

  • All simulations are at full scale
  • Simulations use realistic inertias and centres of gravity (something not feasible in tank testing)
  • Oblique incident waves coming from any direction can be simulated, tank testing is usually limited to head waves
  • Decomposition of individual forces and moments for the hull and each appendage
  • Precise analysis of motion velocities, accelerations and trajectories of the body
  • Flow visualisation and animation to gain insight and understanding about differences between designs
  • Simulations are 100% reproducible
  • Hull or appendage shapes can be easily changed without building new models
  • It is easy to test many design configurations i.e. to swap appendages Easily test in a variety of sailing conditions (speed, wave characteristics) to compare performance
  • Time and cost reduction
 

Ship Design Optimisation

Cape Horn Engineering has pioneered RANSE based CFD since its very beginning and continues its research work on a daily basis. With our proven track record in yacht racing design, we can apply this cutting edge technology to a variety of marine vessels including commercial ships, cargo ships, service operation vessels and work boats, to enhance energy efficiency, improve performance, comfort and safety, reduce emissions and save on fuel.

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Wind Propulsion Technology (WPT)

To address the global challenge of reducing emissions for commercial shipping, shipping companies are look for carbon-free alternatives by testing potential solutions for vessels, and the introduction of WPT (Wind Propulsion Technology) has been evaluated. Due to our renowned experience and specialist technology, we are able to offer a holistic analysis of the benefits of WPT and have developed a simulation workflow to directly compare the efficiency of wind assisted ship propulsion (WASP) devices.

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Simulations

High-fidelity CFD with rotating propellers

Simulated constant RPM propeller performance, including roll stabilisers and superstructure windage, to assess vessel speed and shaft power on the award-winning Najiba.

Versatile hydrodynamic analysis

Examples include resistance, propulsion, seakeeping, slamming, and exhaust dispersion simulations for a range of motor yachts and commercial ships.

Realistic 4DOF motion simulation

Simulated yacht motion in 2.5m waves at 30° from stern. Captured realistic surging effects, with speed fluctuating ±7 knots around an average of 9.6 knots.

Integrated air & water flow simulation

Developed a workflow to evaluate Flettner rotors, wings, and other WASP devices by simulating hull-water and superstructure-air interaction simultaneously.

Innovative low-emission sail design

Simulation and analysis of rigid sail systems designed to cut emissions in commercial shipping — a new approach to auxiliary wind power.

6DOF control with rudders and fins

Full-scale manoeuvre trial simulation of a 50m superyacht, following ITTC standards using active rudders and stabilisers in a dynamic 6-degree-of-freedom model.