Research on airfoil surface flow structure testing based on Tuft velocity measurement method

Abstract

Fluorescent tuft visualization technology, as a practical and convenient technique, has attracted widespread attention. In this study, a novel fluorescent tuft velocity measurement method is developed based on existing technologies. This method involves the recognition of tuft deflection angles, image transformation, block processing, temporal averaging, and post-visualization processing. Additionally, quantitative measurement of flow field velocity is achieved through tuft calibration. The study begins by comparing tufts of different materials, examining both fluorescent and deflection characteristics to determine optimal tuft parameters. The impact of tuft length on deflection characteristics is also investigated. Finally, the cotton tuft with a length of 7 mm and a diameter of about 0.1 mm was obtained as the best tuft sought in this experiment. Subsequently, at Reynolds number Re = 1.7 × 105, airfoil surface flow field visualization and quantitative analysis are conducted, exploring the relationship between airfoil surface flow structure and aerodynamics at different angles of attack. Finally, a comparative study is conducted between tuft velocity results and oil flow visualization experiments, as well as particle image velocimetry experiments, confirming the feasibility of the fluorescent tuft velocity measurement method.