Hypersonic force measurements using internal balance based on optical micromachined Fabry-Perot interferometry

Area of Science:

• Aerospace Engineering
• Optical Metrology
• Materials Science

Background:

• Hypersonic aerodynamic force measurements require robust instruments due to harsh environments (high vacuum, electromagnetic interference, dust).
• Traditional foil resistive strain gauges face limitations in extreme conditions.

Purpose of the Study:

• To demonstrate a reliable and robust three-component internal balance for hypersonic aerodynamic force measurements.
• To utilize novel optical micromachined Fabry-Perot interferometric (FPI) strain gauges as sensing elements.

Main Methods:

• Fabrication of FPI gauges using Micro-Opto-Electro-Mechanical Systems (MOEMS) techniques.
• Utilizing high-reflectivity coatings for high-resolution Fabry-Perot cavities.
• Employing antireflective and passivation coatings to minimize interference.
• Calibration and evaluation of the FPI strain gauge balance in Mach 5 hypersonic flow.

Main Results:

• The FPI strain gauge based balance was successfully calibrated and evaluated in a Mach 5 hypersonic flow.
• Performance comparison with traditional foil resistive strain gauge balances was conducted.
• The proposed balance demonstrated reliability and robustness.

Conclusions:

• The MOEMS FPI strain gauge based balance is a reliable and robust alternative for hypersonic aerodynamic force measurements.
• The developed balance is potentially suitable for the challenging conditions of hypersonic wind tunnels.