Surface-Flow Patterns A Swept-Back Wing

摘要

Effects of the Reynolds number and angle of attack on the surface flow, the aerodynamic performance, and the vortex shedding of a finite swept-back wing are experimentally studied The cross-sectional profile of the wing is NACA 0012, and the swept-back angle is 15 degrees. The surface flow field is visualized by surface oil-flow techniques. Six characteristic flow regimes, laminar separation, separation bubble, leading-edge bubble, bubble burst, turbulent separation, and bluff-body wake, are studied, with the consideration of Reynolds numbers and the angles of attack. The aerodynamic performances detected by a six component balance show there is no hysteresis phenomenon for the swept-back wing model under the conditions used in this study. With the time series signals detected by hot-wire in the wake region, four significant modes, laminar, subcritical, transitional, and supercritical, can be defined. The derived Strouhal number distributions are significantly distinguished in these four modes. In addition, the statistical properties of turbulence, e. g., the power spectrum density function, probability density function, and correlation coefficient, are also discussed in this paper.