A simple method for estimating transition locations on blade surface of model propellers to be used for calculating viscous force

Effects of inflow Reynolds number (Re), turbulence intensity (I) and pressure gradient on the transition flow over a blade section were studied using the γ-Reθ transition model (STAR-CCM+). Results show that the ReT (transition Re) at the transition location (PT) varies strongly with Re, I and the magnitude of pressure gradient. The ReT increases significantly with the increase of the magnitude of favorable pressure gradient. It demonstrates that the ReT on different blade sections of a rotating propeller are different. More importantly, when there is strong adverse pressure gradient, the PT is always close to the minimum pressure point. Based on these conclusions, the PT on model propeller blade surface can be estimated. Numerical investigations of pressure distribution and transition flow on a propeller blade section prove these findings. Last, a simple method was proposed to estimate the PT only based on the propeller geometry and the advance coefficient.