A parametric study for a flettner rotor in standalone condition using CFD

In this study, the performance prediction and parametric study of a Flettner rotor in standalone condition was conducted based on a computational fluid dynamics (CFD) approach. A method for predicting the rotor performance based on steady RANS simulation was established, and the present method was validated with a reference rotor model in which wind tunnel test results were published. The CFD results depending on the turbulence models including k-omega shear stress transport (SST), k-epsilon, Spallart-Almaras and Reynolds stress model, and the non-dimensional wall distance (y+) as well as boundary conditions were compared with the experimental results. A model scale condition with a similar rotor diameter was considered to apply the CFD analysis method to the target rotor dimension. The CFD results based on the Reynolds number (Re) and y + values were compared in the model scale. In addition, a comparative analysis was performed on the model and prototype size under the same Re condition. Consequently, an appropriate condition for the CFD analysis was proposed and the lift, drag, torque and energy efficiency of the target rotor design were predicted. Based on this, parametric investigations for the rotor aspect ratios from 4 to 6 and the diameter ratio of the disk and rotor cylinder from 1.5 to 8 were conducted. The effect of aspect ratio was examined by varying the rotor diameter while maintaining the height. Furthermore, the torque components generated by the rotor cylinder and disk owing to the aerodynamic load were analyzed.