Numerical Research on Usage of Podded Propulsors in Ice Management

Abstract

Although podded propulsor technology has existed for nearly two decades, there has been little research into the use of these propulsors for ice management. Full-scale ice management trials with azimuthing thrusters revealed that it was possible to break and clear ice with the propulsors' wake and that precise ice management could be achieved with the wake of this propulsion system. This means dynamic placement ofpropeller wake wash can facilitate ice breaking and ice management operations. This paper presents preliminary outcome of a research program to evaluate the potentials ofpodded propulsors as an ice management device.The kinematics i.e. the turbulence and velocity distribution in the propeller wake wash determines the capacity of the propulsor to break, push and clear the ice. In this research, efforts are made to model the propeller wash and data were predicted to quantify the capacity of a podded propulsor to clear ice under a range of operating conditions. A Reynolds-Averaged Navier-Stokes solver is used to predict the propulsive performance of a generic podded propulsor system in various operating conditions and configurations. The effects ofpropeller shaft speed and pod configuration are evaluated. The predicted propeller thrust and torque as well as the loads on the pod are compared with corresponding data acquired in a complimentary experimental program. The simulations and measurements are carried out for both puller and pusher configurations at or near bollard pull condition and in uniform inflow condition. Analysis demonstrates that the RANS solver can accurately predict the performance coefficients of the podded propulsor in straight-ahead condition in both puller and pusher configurations. The kinematics of the propeller wash at multiple downstream locations are studied only to reveal that the pusher propulsor may be more effective in clearing ice than the puller one because of less interaction between the propeller and the strut. The current work aims to provide insight into the effect of propeller shaft speed and pod configurations on the quality of the propeller wake that can be used for ice management.

Experimental Investigation of Propeller Wake Velocity Field to Determine the Major Factors Affecting Propeller Wake Wash

“…A detailed model-scale experimental study on a propeller wake velocity field in the vicinity of the propeller was performed in the large circulating water channel of CNR-INSEAN using LDV (Laser Doppler Velocimetry) measurement techniques [6]. Islam [7] investigated the kinematics of propeller wake wash for ice management by using podded propulsors (both puller and pusher arrangements) at different shaft speeds, pod configurations, and propeller inclinations.…”