Marine Propeller Optimisation - Strategy and Algorithm Development

To design the optimal propeller you have to take a multitude of choices into account, but to make the life of the propeller designer easier, Florian Vesting, PhD Student at the Department of Shipping and Marine Technology at Chalmers, developed a tool box of strategies and algorithms. October 9 he defends his thesis. 

Tell us about your research!
The essence of my work are design strategies and algorithms to make automated optimisation practical and applicable in propeller design on an everyday-to-use basis. The problem with propeller design is the fact that it is restricted by numerous limitations like classification rules, manufacturing restriction, or physical behaviour (i.e. cavitation), which makes it difficult for automated optimisation. Typically academic propeller optimisation cases do not account for all design restriction, which often hinder convergence of the optimisation. I didn’t invent propeller optimisation, however, I designed new constraints and developed algorithms which make optimisation more applicable in order to find better blade design solutions faster.

How does your research make the life of the propeller designer easier?
Propeller design is not an easy task; a designer has to consider numerous limitations for a design. There is no remedy if you want to find the best possible solution. However, with an automated design toolbox, which accounts for all these limitations, and guidelines, the designer can investigate more possible designs in the same lead time. This yields eventually better performance.

What is the greatest challenge for propeller designers of today?
Propeller designers are often under enormous pressure to provide accurate performance predictions and high performance quality. This happens often in a challenge with competitors where lead time is restricted and thereby the number of design that can be evaluated. Thus, the designer who still can evaluate a large number of design alternatives is more likely to find the best design trade-off.

Has anyone been anticipating your results?
The project is supported from the Rolls-Royce´s University Technology Centre here at Chalmers. We have been working closely together with Rolls-Royce Hydrodynamic Research Centre in Kristinehamn, where the Rolls-Royce propellers are designed. The ideas, strategies and algorithms are implemented in their design toolbox, which made it possible to test on contemporary designs. The blade design team is using the toolbox and the optimisation add-on in their daily work. For the future we plan to make it easier accessible, to include more options for objectives, and to make the optimisation algorithms even smarter.

Which factors influence the design of propellers of today? 
Propeller efficiency is the top priority. This is typically motivated by fuel consumption and corresponding emissions. This a worrying trend from the prospective of a propeller designer since it yields sub-optimal design solutions. For a sustainable propeller design, which works satisfying throughout the lifetime of the ship, the designer has to consider all important influence factors, e.g. cavitation, noise and vibration, and find the best possible trade-off.

Florian Vesting at Chalmers Publication Library