Analysis of a propeller wake flow field using viscous fluid mechanics

Abstract

The computational fluid dynamics (CFD) method is used to numerically simulate a propeller wake flow field in open water. A sub-domain hybrid mesh method was adopted in this paper. The computation domain was separated into two sub-domains, in which tetrahedral elements were used in the inner domain to match the complicated geometry of the propeller, while hexahedral elements were used in the outer domain. The mesh was locally refined on the propeller surface and near the wake flow field, and a size function was used to control the growth rate of the grid. Sections at different axial location were used to study the spatial evolution of the propeller wake in the region ranging from the disc to one propeller diameter (D) downstream. The numerical results show that the axial velocity fluctuates along the wake flow; radial velocity, which is closely related to vortices, attenuates strongly. The trailing vortices interact with the tip vortex at the blades’ trailing edge and then separate. The strength of the vortex shrinks rapidly, and the radius decreases 20% at one diameter downstream.

Keywords

computational fluid dynamics (CFD) / viscous fluid mechanics / sub-domain hybrid mesh / wake velocity field

References

[1] Jessup SD (1998). An experimental investigation of viscous aspects of propeller. The 22nd ITTC Propulsion Committee Propeller RANS/Panel Method Workshop Proceedings, Washington, 200–205.

[2] Krasilnikov V, Sun Jiaying, Halse KH (2009). CFD investigation in scale effect on propellers with different magnitude of skew in turbulent flow. The First International Symposium on Marine Propulsors, Trondheim, 25–40.

[3] Mitja M, Enrico N (2009). Comparison of hexa-structured and hybrid-unstructured meshing approaches for numerical prediction of the flow around marine propellers. The First International Symposium on Marine Propulsors, Trondheim, 500–507.

[4] Paik B.G., Kim J., Park Y.H., Kim K.S., Yu K.K. Analysis of wake behind a rotating propeller using PIV technique in a cavitation tunnel. Ocean Engineering, 2007, 34: 594-604

[5] Stella A., Guy G., Di Felice F. Propeller wake flow field analysis by means of LDV phase sampling technique. Experiments in Fluids, 2000, 28: 1-10

[6] Su Y., Huang S. Ship propeller theory, 2003, Harbin, China: Harbin Engineering University Press, 159-160

[7] Su Y., Ikehata M., Kai H. Numerical analysis of the flow field around marine propellers by surface panel method. Ocean Engineering, 2002, 20(3): 44-48

[8] Watanabe T, Kawamura T, Takekoshi Y, Maeda M, Rhee SH (2003). Simulation of steady and un-steady cavitation on a marine propeller using a rans cfdcode. The Fifth International Symposium on Cavitation, Osaka, 502–506.

[9] Ye J., Xiong Y. Prediction of podded propeller cavitation using an unsteady surface panel method. Journal of hydrodynamics, 2008, 20(6): 790-792