A Study on the Optimum Propeller at Full Scale Condition, Part 1: Effect of the Reynolds Number on the Open Water Characteristics of Propellers with Laminar Flow Blade Section

Abstract

The Reynolds number effect on the open water characteristics of a propeller with a laminar type blade section has been studied by CFD and compared with the experiment. At a Reynolds number of model tests, the boundary layer flow over the blade is mostly laminar, while it becomes almost fully turbulent at a full scale Reynolds number. Because of this fact, the Reynolds number effect is very complicated. When the Reynolds number is increased from the model scale to the full scale, the open water efficiency first increases, and then start to decrease because of the transition of the boundary layer. As the boundary layer becomes almost fully turbulent, the open water efficiency again increases with increasing Reynolds number. It has been also shown that the transition Reynolds number of a propeller with laminar type blade section is higher than that of a propeller with MAU type blade section.

The open water efficiency of a model test at a sufficiently high Reynolds number is close to that at a full scale Reynolds number. However, because the open water efficiency of model tests is significantly dependent on the Reynolds number, the selection of the Reynolds number in model tests is of critical importance.