Air-lubrication for oceangoing vessels

The project aims to reduce fuel consumption from oceangoing vessels, which is a required contribution towards zero emission shipping. More than 70% of resistance of oceangoing vessels is skin friction. Application of effective air-lubrication reduces the skin friction. Current air-lubrication systems (ALS) report up to 10% net savings depending on vessel type and operation. This number shows improvement potential considering the large portion of skin friction. This project will provide knowledge on ALS to shipping industry so that more ships are built or retrofitted with ALS. This is done by multi-disciplinary approach, considering the whole system. ALS requires powerful compressors for injecting air bubbles or air layers on the wetted surface of the vessel. Effective performance and power usage of compressors is essential to achieve improved net savings. The physics of air lubrication are not fully understood. This project will perform numerical simulations, laboratory experiments, full scale field measurements and monitoring to highlight mechanism of air-lubrication and propose improvements. Moreover, effect of advanced surface structures on further reduction of skin friction in combination with ALS will be studied. The effect of ALS on biofouling will be investigated. The propeller will operate in lighter loading condition when resistance is reduced. Customized propeller design is required that shall also take into account that the ALS might not operate all the time, e.g. in heavy seas. Customized hull design will be considered to achieve more effective air-lubrication and less unfavourable interaction with the propeller.

The project aims to reduce fuel consumption from oceangoing vessels, which is a required contribution towards zero emission shipping. More than 70% of resistance of oceangoing vessels is skin friction. Application of effective air-lubrication reduces the skin friction. Current air-lubrication systems (ALS) report up to 10% net savings depending on vessel type & operation. This number shows improvement potential considering the large portion of skin friction. This project will provide knowledge on ALS to shipping industry so that more ships are built or retrofitted with ALS. The project aims also to improve the net savings by 5%. This is done by multi-disciplinary approach, considering the whole system. ALS requires powerful compressors for injecting air bubbles or air layers on the wetted surface of the vessel. Effective performance & power usage of compressors is essential to achieve improved net savings. This would include piping & temperature of compressed air. The physics of air lubrication are not fully understood. This project will perform numerical simulations, laboratory experiments, full scale field measurements & monitoring to highlight mechanism of air-lubrication & propose improvements. Moreover, effect of advanced surface structures, e.g. riblets, on further reduction of skin friction in combination with ALS will be studied. The effect of ALS on biofouling will be investigated. The propeller will operate in lighter loading condition when resistance is reduced. Customized propeller design is required that shall also take into account that the ALS might not operate all the time, e.g. in heavy seas. Customized hull design will be considered to achieve more effective air-lubrication & less unfavourable interaction with the propeller. The consortium includes complete chain of stakeholders, 3 ship owners, hull designer & propeller manufacturer, coating supplier, compressor manufacturer, air-lubrication manufacturer, a research institute & a university.