Measurement of gas-phase temperatures in flames with a point-diffraction interferometer

Area of Science:

• Optical diagnostics
• Thermometry
• Fluid dynamics

Background:

• Accurate gas-phase temperature measurement is crucial for combustion analysis.
• Traditional methods like thermocouples have limitations in flames.
• Point-diffraction interferometry (PDI) offers a non-intrusive optical alternative.

Purpose of the Study:

• To evaluate the performance of a PDI system for measuring gas-phase temperatures.
• To compare PDI temperature measurements with thermocouple data in various thermal environments.
• To assess PDI's suitability for flame and boundary layer diagnostics.

Main Methods:

• Experiments utilizing a point-diffraction interferometry (PDI) system.
• PDI measures the refractive index in two dimensions by generating a reference beam post-test section.
• Comparison of PDI data with thermocouple measurements in thermal boundary layers and diffusion flames.

Main Results:

• PDI demonstrated excellent agreement with thermocouple measurements for thermal profiles in boundary layers.
• PDI flame temperature measurements were within the uncertainty range of thermocouple data, considering radiation corrections.
• The system effectively measures refractive index, enabling 2D temperature mapping.

Conclusions:

• PDI is a high-performance technique for accurate gas-phase temperature measurements.
• PDI offers a viable alternative to thermocouples, especially in challenging flame environments.
• The study validates PDI's capability for detailed thermal diagnostics in fluid dynamics research.