Hydrodynamic performance of a rim-driven thruster improved with gap geometry adjustment

Abstract

The hubless rim-driven thruster (RDT) has become increasingly interesting for ship propulsion. Gap flow has been proven as the main feature of RDT that cannot be simply neglected. In this study, based on a classical hubless RDT, the effects of the gap geometry are studied by adjusting its axial passage length, and inlet and outlet oblique angles. The hydrodynamic characteristics of the RDT were simulated with OpenFOAM based on the k – ω shear stress transport turbulence model. Due to the pressure increase after the main flow passes through the rotating blades, the flow inside gap is driven upstream, which is opposite to the main flow direction. It is found that the hydrodynamic efficiency is increased as the gap axial passage length is shortened, which is realized by increasing the oblique angle with the fixed inlet and outlet positions. Moving the inlet and outlet to further downstream and upstream positions has negligible effects on the hydrodynamic efficiency and leads to recirculating flow within the gap near its inlet. These findings shed light on the design of the gap geometry to improve the RDT hydrodynamic performance.

KEYWORDS:

• Hubless rim-driven thruster
• gap flow
• hydrodynamic performance
• numerical simulation

Acknowledgments

The authors would also like to appreciate the Swedish National Infrastructure for Computing (SNIC) for providing computer resources at the Chalmers Centre for Computational Science and Engineering (C3SE).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the LIGHTHOUSE (Swedish Maritime Competence Center) [grant number FS24_2022/Hållbar sjöfart], and China Scholarship Council [grant number 202106680052].