This paper presents the first implementation of a novel class of dynamic time-resolved direct skin friction measurements sensor based on active ionic polymer transducers. These ionic polymer sensors have the advantage that they contain no moving parts, perform a direct measurement of shear, and can be mounted directly to the surface of an existing vessel with no modification. During the present effort we characterize the accuracy of the sensors and validate their dynamic measurement response. Using an oscillating Stokes layer calibration procedure we demonstrate measurement accuracy in fluctuating shear on the order of 4.92% over a range of stresses of +/- 3 Pa and signal-to-noise-ratio on the order of 60 dB. The frequency response of the sensor is over 10 kHz however due to experimental limitations we were not able to calibrate for frequencies higher than 140 Hz. These sensors have been shown to be insensitive to vibration or pressure. Also, an automatic change of impedance compensation approach is proposed that allows in-situ recalibration of the sensors and accounts for environmental effects such as changes of temperature on the sensors performance. The results demonstrate the potential for using ionic polymer sensors to perform accurate, high frequency measurements of shear in turbulent boundary layers.
A Dynamic Wall Shear Stress Sensor Based on Ionic Polymers
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Etebari, A, Bennett, MD, Leo, DJ, & Vlachos, PP. "A Dynamic Wall Shear Stress Sensor Based on Ionic Polymers." Proceedings of the ASME 2005 Fluids Engineering Division Summer Meeting. Volume 2: Fora. Houston, Texas, USA. June 19–23, 2005. pp. 483-492. ASME. https://doi.org/10.1115/FEDSM2005-77484
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