Amirkabir Journal of Mechanical Engineering

Amirkabir Journal of Mechanical Engineering

Numerical Optimization of the Spacing Ratio in a Marine Toroidal Propeller Using CFD and Genetic Algorithm with Comparison to the KP505 Reference Propeller

Document Type : Research Article

Authors
MohammadHasan Ahmadi 1
Rouzbeh Shafaghat 2
Mohsen Zamani 1
Behrad Alizadeh Kharkeshi 3
1 Sea-Based Energy research group, Babol Noshirvani University of Technology
2 Department of Mechanical Engineering, Babol Noshirvani University of Technology
3 Faculty of Mechanical Engineering, Babol Noshirvani University of Technology
10.22060/mej.2026.25245.7933
Abstract
Numerical simulations were performed using STAR-CCM+ software, and optimization was carried out with a genetic algorithm. The ducted propellers were innovatively designed based on the KP505 propeller. Simulations were conducted at six pitch ratios. To evaluate the results and perform optimization, thrust, torque, and efficiency coefficients were considered as objective functions. The results showed that the thrust coefficient exhibited a decreasing trend at low advance ratios, a non-linear behavior at medium advance ratios, and an increasing trend at high advance ratios as the pitch ratio increased. A comparative analysis revealed that before optimization, the ducted propeller's thrust coefficient was at best 15% higher than that of the KP505 propeller at an advance ratio of 0.8. The optimal pitch ratio obtained after optimization was 0.2641, corresponding to a maximum efficiency of 45.35% for the ducted propeller. Performance comparison between the optimized ducted propeller and the KP505 propeller showed that the optimized ducted propeller could increase thrust by up to 26% (at an advance ratio of 0.8) and improve efficiency by 7.84% at an advance ratio of 1.0. Flow analysis also indicated that increased velocity behind the propeller and an improved pressure pattern in the optimized ducted propeller contribute to higher thrust and reduced cavitation risk.
Keywords
Numerical Study
Toroidal Propeller
Spacing Ratio
Optimization
KP505 Propeller
Subjects
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Amirkabir Journal of Mechanical Engineering
Volume 57, Issue 10
January 2026
Pages 1359-1386