A Novel Leading-Edge Tubercle Flow Control Energy Saving Device for Ships

• Main Author: Pena, Blanca
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: UCL (University College London) 2020
• Subjects: Humpback Whale
• Online Access: https://discovery.ucl.ac.uk/id/eprint/10118648/

The International Maritime Organisation (IMO) recently stated that the shipping industry’s CO2 emissions should be reduced by 50% (compared to 2008) before 2050. From the hydrodynamic perspective, existing Energy Saving Devices (ESDs) or flow controllers do not provide sufficient emissions savings to make a significant contribution towards meeting the IMO’s emission targets. Therefore, there is scope for the development of new and more efficient ESDs that can replace or supplement the existing ones. As ESDs are produced, it is important that their performance can be evaluated prior to full-scale production. This could be problematic since existing numerical methods exhibit shortcomings such as scaling and turbulence modelling accuracy. This work has proposed and investigated the feasibility of a novel flow control technology, named the ‘LET-Performance’, inspired by the Leading-Edge Tubercle (LET) flippers of the humpback whale, acting at the stern of the ship as a turbulent regime boundary layer controller. Existing literature mainly covers hydrofoils in transitional and laminar flow regimes, therefore, a further investigation into LET hydrofoil performance in turbulent flow regimes was also required. To assess the performance of the novel LET-Performance, a suitable numerical approach for ESD performance evaluation was also studied. This work confirmed that an Improved Delayed Detached Eddy Simulation (IDDES) based numerical model is suitable for assessing the performance of ESDs due to its capability to accurately model the turbulence contained in the flow. Also, an LET hydrofoil primary mechanism of action in turbulent regime was identified and found to provide a more stable flow when compared to transitional or laminar flow regimes; giving the foundation to design the novel device. In particular, the LET-Performance achieved an overall ship boundary layer thickness reduction and wake stability. As a result, full-scale numerical investigations conducted on a general cargo ship revealed a 6.5% resistance ...