Session: 05-05: Combustion Measurements 2

Submission Number: 178275

3D Measurements of Temperature and CH* Chemiluminescence Distributions in Swirling Flames 

Swirling flames, prevalent in gas turbines, are strongly influenced by the turbulent and asymmetric flows within the combustion chamber, which critically impact combustion efficiency, pollutant emissions, and operational safety. These challenges have driven the advancement of diagnostic techniques towards three-dimensional (3D) and multi-parameter measurements. Tomographic methods have emerged as a key solution, enabling the 3D estimation of critical parameters such as velocity, temperature, soot concentration, and chemiluminescence. A particularly powerful approach involves the simultaneous application of multiple tomographic techniques to gain a more comprehensive characterization of the flame.

This work demonstrates such a multi-parametric capability by integrating single-shot tomographic atomic fluorescence (TAF) and computed tomographic chemiluminescence (CTC) to simultaneously reconstruct the 3D temperature and CH* chemiluminescence fields. This simultaneous measurement provides a unique opportunity to investigate the intrinsic correlation between the flame structure (inferred from CH* chemiluminescence as a marker of heat release rate) and the temperature distribution downstream.

The technique was applied to a lean premixed methane-air swirling burner. The 3D temperature field was measured via two-line atomic fluorescence using cesium (Cs) as a tracer. A CsCl solution was atomized into the air stream, delivering cesium vapor into the flame, where it was excited and emitted characteristic radiation. For simultaneous data acquisition, two "one-to-nine" optical fiber bundles were arranged around the flame to collect sufficient projection data. One bundle was coupled to a scientific-grade camera to capture the CH* chemiluminescence signals for 3D CTC reconstruction. The other bundle was connected to a beam splitter, directing the light to two separate cameras equipped with 850 nm and 890 nm narrow-band bandpass filters, respectively. The intensity ratio of the Cs fluorescence lines at these two wavelengths was used to reconstruct the 3D temperature field based on the Boltzmann distribution law. All three cameras were synchronized by a common controller.

The presented results are expected to elucidate the correlation between the CH* chemiluminescence and the temperature distribution in the downstream region of the swirling flame.

Presenting Author: Naying Wei Northwestern Polytechnical University

Presenting Author Biography: Naying Wei received the B.S. degree in Communication Engineering from North University of China, Shanxi, China, in 2021 and the M.S. degree in Electronic Information Major from North University of China, Shanxi, China, in 2024. She is currently working toward the Ph.D. degree in Aeronautical and Astronautical Science and Technology with the School of power and energy, Northwestern Polytechnical University, Shaanxi, China. Her research interests include Combustion Diagnosis and 3D Reconstruction of flame.

Authors:

Naying Wei Northwestern Polytechnical University
Xiang Li Northwestern Polytechnical University
Wei Fan Northwestern Polytechnical University
Qingchun Lei Northwestern Polytechnical University