Screw propellers have remained nearly unchanged for the last 150 years, and have been the propulsion system of choice for nearly all marine vessels over that time. The efficiency of this propulsion system has a significant impact on both the economic and environmental aspects of marine transportation. We were inspired by the Shrraw propellers, shown in the figure. The Sharrow website claims that their propeller is more efficient. This project aims to compare the efficiency of toroidal propellers and standard propellers. We used the Solidworks to create the different propellers. Ansys workbench workflow and Ansys Fluent are used to analyze and compare the performance of the geometries.

The project aimed to leverage the skills learnt in the Computational analysis of transport phenomena class and apply the skills to compare different propellers. We used Solidworks to create the standard geometry and the two different toroidal geometry. We created the geometries by looking at the pictures on Sharrow's website. 

My teammates carried out a thorough literature review on propeller analysis. They figured out how to calculate the advance ratio which will normalize the effect of different propeller sizes. For the different advance ratios and initial velocities, we calculated the efficiencies for the standard and toroidal propellers. 

I ran the simulations for all the propellers using an HPC. To create the workflow to test the different propellers, I used Ansys workbench. I used Spaceclaim to create the propeller domain and ansys meshing to define the solver mesh. I used Ansys Fluent to test the propellers at different inlet velocities to calculate the efficiency of each propeller. From this workflow, I also calculated the lift and torque of the different propellers.  

From this project, we concluded that the blade geometry of a traditional propeller is widely studied and refined, a toroidal propeller designed with very limited knowledge of flow characteristics over the model will perform worse than a standard blade. Further refinement of the blade geometry is required for the toroidal blade, to reduce vorticity at the tips and improve efficiency.