Piezoelectric Floating Element Shear Stress Sensor for the Wind Tunnel Flow Measurement

Area of Science:

• Materials Science
• Mechanical Engineering
• Aerodynamics

Background:

• Accurate measurement of flow-induced shear stress is crucial for understanding aerodynamic phenomena.
• Existing sensors often struggle to isolate shear stress from normal stress, limiting their effectiveness.
• Piezoelectric materials offer potential for sensitive stress detection.

Purpose of the Study:

• To develop a piezoelectric sensor for direct and pure shear stress measurement.
• To suppress the influence of normal stress in flow-induced measurements.
• To characterize the sensor's performance in static and dynamic conditions.

Main Methods:

• Fabrication of a piezoelectric sensor with a floating element and opposing poling vectors.
• Utilization of 0.67Pb(Mg1/3Nb2/3)O3-0.33PbTiO3 (PMN-33%PT) single crystal for high piezoelectric coefficients.
• Calibration and wind tunnel testing, employing cantilever beam theory and signal processing techniques.

Main Results:

• The sensor demonstrated high shear stress sensitivity (91.3 ± 2.1 pC/Pa) and minimal normal stress sensitivity (<1.2 pC/Pa).
• A usable frequency range up to 800 Hz was confirmed.
• In turbulent flow, the sensor achieved a signal-to-noise ratio (SNR) of 15.8 ± 2.2 dB and a sensitivity of 56.5 ± 4.6 pC/Pa.

Conclusions:

• The developed piezoelectric sensor effectively measures pure shear stress in aerodynamic flows.
• The sensor's design successfully mitigates normal stress interference.
• This technology provides a valuable tool for advanced fluid dynamics research.