Influence of Size Effect on Dynamic Characteristics of Hot-film Wall Shear Stress Sensor

Dynamic characteristics is one of the main factors to be considered in turbulence measurement using hot-film sensors. Four sizes of hot-film sensors were fabricated with the same aspect ratio. The size effect on frequency response and sensitivity of hot-film sensor is researched and compared with heat transfer theory. A smaller thermistor has a higher frequency response, which can measure the high-frequency vortex precisely. A larger thermistor can store more heat, resulting in higher sensitivity. The hot-film sensor with 1.8 mm length and 0.03 mm width has more advantages. It can obtain higher frequency response and sensitivity at the same time.