Scale effects on tip loaded propeller performance using a RANSE solver

Traditionally, the quality of alternative propeller designs at full scale has been assessed by means of model scale tests. Due the large differences in Reynolds numbers between model and full scales, model-scale-based performance predictions may be questionable in cases where viscous effects are dominant. This paper presents a numerical study about scale effects on performance coefficients for a CLT propeller with different endplate geometries. Twelve endplate shape variations were analyzed in model and full scale using RANS code FINFLO. The SST k-? turbulence model is used as a basic model for the study. Additional computations are made with other turbulence models. A special procedure for the generation of the computational grids is implemented to minimize computational errors in the comparison of the alternative geometries. The study provides also a RANS-based scale effect on the shape of radial circulation distribution predicted for different geometry variations. The research work gives an insight into which type of modifications at full scale could be analyzed by model scale viscous flow theory or model tests in ranking alternative designs. Differences found between model and full scale numerical results make model scale analysis questionable for some specific type of modifications when full-scale performance is sought