Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Numerical simulation on cavitation Performance of Podded propulsors in oblique flow
JiaChen Ma 1,Xiaoshen Ning1, Fugeng Li1, Weipeng Zhang1, Jian Hu1 *1

College of Shipbuilding Engineering, Harbin Engineering University
Harbin, Heilongjiang, China*Corresponding Author
The boundary element based on potential slow assumption is used todeal with the two-dimensional hydrofoil problem of partial cavitationand then extended to deal with the three-dimensional cavitation.
Kinematic and dynamic boundary conditions are applied to thehydrofoil surface and cavity surface. The predicted cavity shape byKinnas et al (1993) for some 3D hydrofoil geometries is in good
agreement with the experimental results. Later, the computational fluid
dynamics method was adopted by Rhee et al (2005) to study thecavitation flow around marine propellers. It is believed the method is
feasible for practical cavitation propeller design procedures.

ABSTRACTThe hydrodynamic performance of a podded propeller in oblique flow
is investigated in this study. The fundamental simulation is carried out
using Reynolds Averaged Navier–Stokes (RANS) method. The rotating
motion is modeled using the sliding grid technique. The effect ofcavitation on the hydrodynamic performance of the propeller isinvestigated in detail. The results show that the incidence angle andadvance coefficient greatly influence the hydrodynamic performance of
the Podded propulsors. In particular, the load under steady-state
conditions is different from that under maneuvering conditions, andcavitation will reduce the propulsion efficiency of the propeller.

Islam et al. (2015) adopted CFD simulation and used the unsteady
RANS solver to numerically study the hydrodynamics of the podded
propulsion under various static conditions. The results show that theRANS solver can satisfactorily predict the hydrodynamic coefficients.
Zhao et al. (2020) used the RANS method and the SST k-ω turbulencemodel to study the hydrodynamic performance of the podded thruster in
oblique flow.YE et al. (2008) used the surface panel method to predictthe unsteady thin-layer cavitation of the pod propeller. The cavitation
range of the propeller determined by this method is consistent with thatby the cavitation tunnel, which proves the practicability of the method.
Shancheng L et al. (2019) used a fully structured mesh method basedon Reynolds-averaged Navier-Stokes (RANS) to numerically simulate
the cavitation characteristics of the podded propeller. The thrust andtorque in oblique flow are greater than those in straight-ahead flow.
Compared with traditional propellers, the hydrodynamic and cavitation
performance under different oblique flow angles of podded propulsion
was limitedly studied. In this paper, the commercial software
STAR-CCM+ is used for numerical simulation, and the force andtorque of the propeller blade under different oblique flow angles areanalyzed.

KEY WORDS: pod propeller； Cavitation; Hydrodynamic load;
CFD

INTRODUCTION
The pod propulsion is an innovative propulsion system that combines
propellers, pod, strut, and electric motor. Compared with thetraditional propulsion system, the pod propulsion has higher
transmission efficiency, and the propulsion unit is placed under the hulland connected with the hull through a strut, so the entire propulsion
unit can realize 360o continuous rotation. This arrangement makes theoverall structure design of the hull more reasonable. At the same time,
it is also of great help to improve the maneuverability and stability ofthe ship.

METHODOLOGY

Cavitation is a phenomenon observed in high-velocity flows, as
the local fluid pressure reaches its saturated vapor pressure. Tiny gas
nuclei in the water expand and grow into the void bubble. Thecavitation will be especially serious for propellers under highhydrodynamic loads. Cavitation can cause severe erosion of thepropeller blades and the reduction of the hydrodynamic performance(Li Z R 2012, Peters2018). Compared with the traditional
propeller-rudder system, the blade loads and the cavitation performanceof the podded propeller are more complicated. It is necessary to study
the variation of podded propulsion under different oblique flow angles,advance coefficients, and cavitation numbers.

Computational Domain and Grid Conditions
The pod unit consists of propellers, pod, and strut， Table 1 shows
the geometrical parameters of the blade, and the data are derived fromthe work of Akinturk et al. (2012), The propeller diameter is 250mm,
and the hub diameter is 60mm. Fig. 1 shows the geometric dimensionsof all parts except the blade.

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