TUD024 Hydrodynamic Performance of Hulls and Auxiliary Appendages for Wind Assisted Ship Propulsion

Summary of the project

The use of wind propulsion devices has the potential to significantly reduce ship emissions. Unlike conventional ships that mostly sail on a straight course, wind-assisted ships operate at heel and leeway angles to balance additional aerodynamic loads. To maintain stability and maneuverability often extra appendages like keels or fins are required. Under these conditions, the flow field around the hull becomes complex, dominated by numerous vortex systems. Accurate performance assessment of these flows demands high-fidelity computational models.

Despite advances in computational fluid dynamics (CFD), physical experiments remain crucial for validating and refining these numerical models. This project aims to provide validation data matching the detailed requirements of advanced numerical codes by performing high-fidelity flow field measurements during towing tank tests on various hull shapes typical of wind-assisted ships. The study will also investigate the impact of appendages such as bilge keels and fins on the flow field and overall hydrodynamic performance. The high-quality experimental data obtained will facilitate the development of an enhanced, calibrated computational model tailored for predicting the performance of wind-assisted ships. These validated numerical tools will translate model-scale findings into real-world applications, improving full-scale ship performance of wind assisted ships.

Goal of the project

This project aims to advance numerical tools for predicting the performance of wind-assisted ships operating at drift angles and to improve the modeling accuracy of additional appendages. This will be achieved through validation using towing tank model tests and high-fidelity flow field measurements. The towing tank experiments will also experimentally assess the performance of novel auxiliary appendage configurations needed to balance the aerodynamic forces from wind propulsion devices. Flow field measurements will illuminate the complex interactions between the appendages and the ship’s wake field, where the propeller and rudder are influenced by flow structures shedding from the appendages. While these investigations will be conducted at model scale, the results will be translated to full-scale applications

through numerical simulations. These simulations will use a numerical model calibrated and validated with data from the experiments.

By integrating experimental data with advanced numerical simulations, this project will significantly enhance the accuracy of performance predictions and the effectiveness of novel appendage designs, addressing the unique challenges posed by wind-assisted maritime transport.

Motivation

The project is motivated by the target of working towards a zero emission shipping industry. As decided by the international maritime Organization (IMO) the shipping industry should reduce its CO2 emissions in 2050 to a maximum of 50 percent of the level in 2008. To meet these criteria ships need to be more energy efficient preferably using sustainable sources of energy such as wind in the near future. With clearly defined stepwise emission reductions until 2050 the transition towards zero emission shipping hast to start now and cannot be postponed. In hindsight of this the shipping industry has to further invest in the development of innovative zero emission propulsion concepts such as wind assisted ship propulsion.

Innovativeness

The steady improvement of numerical tools has significantly enhanced our understanding of ship hydrodynamics, but these advancements are limited by a lack of detailed empirical data. Traditional towing tank tests provide basic measurements of motions and forces, insufficient for developing high-fidelity numerical models. These models require comprehensive flow field measurements to accurately characterize complex flows, identify regions of flow separation, and measure vortex structures. However, such high-quality measurements are scarce, particularly for the operating conditions of wind-assisted ships.

This project aims to address this gap by conducting model tests with high-fidelity flow field measurements and low uncertainty force measurements. These tests will generate the detailed data necessary for developing advanced numerical tools to predict the performance of wind-assisted ships, especially under drift angles.

Additionally, the project will examine the impact of novel appendage configurations on the flow field, crucial for balancing aerodynamic forces from wind propulsors.

What distinguishes this project is its focus on the specific operating conditions of wind-assisted ships, such as sailing at drift and heel angles, and the use of state-of the-art numerical simulations to evaluate scale effects. This integrated approach will significantly improve the accuracy of performance predictions and the effectiveness of novel appendage designs, advancing the field of wind-assisted maritime transport.

Valorisation

Duration of the project

Start date: 11/09/2024

End date: 11/09/2028