Quantitative Rayleigh thermometry for high background scattering applications with structured laser illumination...

Area of Science:

• * Combustion diagnostics
• * Optical measurement techniques
• * Laser-based thermometry

Background:

• * Measuring flame temperature is crucial for combustion analysis and control.
• * High background scattering, common in sooting flames, significantly hinders traditional Rayleigh thermometry.
• * Existing background correction methods are often inadequate for complex combustion environments.

Purpose of the Study:

• * To demonstrate the efficacy of structured laser illumination planar imaging (SLIPI) for Rayleigh thermometry.
• * To validate SLIPI's capability in high background scattering scenarios, specifically in sooting flames.
• * To provide a robust method for full-field temperature measurement in challenging combustion environments.

Main Methods:

• * Employed crossed coherent laser beams to generate an interference pattern for structured illumination.
• * Utilized the modulated Rayleigh signal as a signature to differentiate from background scattering.
• * Validated the experimental approach in methane/air flames and applied it to sooting ethylene/air flames.

Main Results:

• * SLIPI demonstrated simplified background correction, improving measurement accuracy.
• * Temperature measurements in methane/air flames showed excellent agreement with prior data.
• * Applied to sooting flames, SLIPI provided reliable temperature data where standard methods failed.
• * SLIPI results showed good agreement with thin-filament pyrometry at the flame interface.

Conclusions:

• * Structured laser illumination planar imaging (SLIPI) is a powerful technique for Rayleigh thermometry in high background scattering conditions.
• * SLIPI offers a simplified and effective approach to background correction, crucial for sooting flames.
• * This method advances the capability for accurate, full-field temperature measurements in complex combustion systems.