Differential-pressure fiber-optic airflow sensor for wind tunnel testing

Area of Science:

• Optoelectronics
• Fluid Dynamics
• Sensor Technology

Background:

• Traditional airflow measurement methods face limitations in precision and range.
• Wind tunnel testing requires accurate differential pressure sensing for aerodynamic analysis.
• Fiber-optic sensors offer advantages in harsh environments and remote sensing applications.

Purpose of the Study:

• To propose and demonstrate a differential-pressure fiber-optic airflow (DPFA) sensor for wind tunnel testing.
• To integrate the DPFA sensor with a Pitot tube for airspeed indication.
• To evaluate the sensor's performance in measuring airflow velocity and its application in aerodynamic studies.

Main Methods:

• Utilizing Fabry-Perot (FP) interferometry to form a differential pressure sensing cavity.
• Coupling the FP sensor with a Pitot tube to measure total and static pressures.
• Employing a white light interferometric (WLI) interrogator with a 100 Hz sweep frequency for cavity length monitoring.
• Applying Bernoulli's equation to derive airflow velocity from differential pressure changes.

Main Results:

• The DPFA sensor demonstrated a measurable range of 0–11 kPa, sensitivity of 826.975 nm/kPa, and resolution of 0.008% (0.89 Pa).
• The integrated system accurately measured airflow velocities from 2.0 to 119.24 m/s with 0.61% accuracy.
• Experimental results for a flat-plate boundary layer were consistent with theoretical analysis and standard electronic pressure transducers.

Conclusions:

• The developed DPFA sensor system offers high precision, a wide measurable range, and high sweep frequency.
• The system exhibits significant potential for wind tunnel experimental investigations.
• The technology is also suitable for in-flight airspeed measurements, enhancing aviation safety and research capabilities.