Laser-absorption mass flux sensor for high-speed airflows.

Area of Science:

• Physical Chemistry
• Spectroscopy
• Fluid Dynamics

Background:

• Accurate measurement of air mass flux is critical in various scientific and engineering fields.
• Existing methods for measuring gas density and velocity can be limited in speed and precision.

Purpose of the Study:

• To present a novel laser-based sensor concept for simultaneous measurement of oxygen density and velocity.
• To demonstrate the sensor's capability in high-speed gas flow conditions.

Main Methods:

• Utilized wavelength modulation absorption spectroscopy with an AlGaAs laser diode targeting the O(2) b(1)Sigma(g)(+)(v' = 0)-X(3)Sigma(g)(-)(v'' = 0) system.
• Employed 10 MHz modulation frequency and second-harmonic detection for enhanced sensitivity.
• Tested the sensor in a shock tube generating high-speed oxygen flow.

Main Results:

• Successfully demonstrated simultaneous measurement of oxygen density and velocity.
• Achieved a measurement time of 0.5 ms with typical absorption levels of 0.5%.
• Validated the sensor's performance in a challenging high-speed flow environment.

Conclusions:

• The presented laser-based sensor concept offers a promising approach for air mass flux determination.
• The simultaneous density and velocity measurement capability is advantageous for dynamic flow analysis.
• The rapid measurement time and demonstrated performance in shock tube experiments highlight its potential for various applications.