Large eddy simulation of end effects on a cylinder rotor

Abstract

Due to the limited length of cylinders, their use in practical engineering inevitably involves end effects, which results in three-dimensional flows at the ends of cylinders. These flow fields are the main factor influencing the aerodynamic and flow field characteristics of cylinders. Regarding a finite-length cylinder rotor, a specific pattern of tip vortices will form under the action of rotation, resulting in notable differences in the aerodynamic characteristics between an ideal two-dimensional cylinder and a finite-length cylindrical rotor. In the present study, the large eddy simulation method is used to systematically investigate cylinder rotors with various aspect ratios. By analyzing the sectional aerodynamic and flow field characteristics, the variation laws of the aerodynamic force, wind pressure, and flow field characteristics of cylinder rotors under the influence of end effects were summarized. The results show that the influence range and intensity of the tip vortices on the rotor flow field and sectional aerodynamic characteristics are dominated by the dimensionless rotating speed, which in turn affects the range of the end effects. The development trend of the tip vortices is analyzed and discussed from multiple aspects, including sectional aerodynamics, the pressure coefficient, and the flow correlation, and an attempt is made to explain changes in the phenomenon.