진동하는 타원형 에어포일의 근접후류 특성 연구

Abstract

An experimental study was carried out to investigate near-wake characteristics of an elliptic airfoil oscillating in pitch. The airfoil was sinusoidally pitched about the half chord point between -5°and +25°angles of attack at the frcestrcam velocities of 3.4 and 23.1 m/s. The corresponding Reynolds numbers based on the chord length were 3.3× 10^4 and 2.2×10^5, respectively. A hot-wire anemometer was used to measure the near-wake flow variables at the reduced frequency of 0.1. Ensemble-averaged velocity and turbulence intensity profiles were presented to examine the near-wake characteristics depending on the Reynolds number. The axial velocity deficit in the near-wake region tends to decrease with the increase in the Reynolds number as found in many stationary airfoil tests. Turbulence intensity in the near-wake region have a tendency to decrease with the increase in the Reynolds number during the pitch-up motion, whereas it shows different feature during the pitch-down motion according to the separation characteristics.<br/>