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Characterization of a high-pressure flame facility using high-speed chemiluminescence and OH LIF imaging

Authors: Will Swain, Yejun Wang, Pradeep Parajuli, Matthew Hay, Ahmad Saylam, Thomas Dreier, Christof Schulz, and Waruna Kulatilaka

Document type: Published journal article

Journal: Experiments in Fluids

Publication details: Volume 64, Issue 4, Article 71, 2023

Published online:

Access and rights note: This page provides bibliographic information and an independently written technical summary. The final Springer Nature Version of Record is not hosted on this website.

DOI: 10.1007/s00348-023-03611-0

Independent technical summary

The study develops and characterizes a laboratory-scale, optically accessible high-pressure burner facility operating with premixed methane–air flames. The facility is intended as a controlled testbed for optical combustion diagnostics and for investigations of flame behaviour, soot formation and minor species at elevated pressure.

Flame behaviour was examined using kHz-rate hydroxyl and methylidyne chemiluminescence imaging, OH laser-induced fluorescence imaging and two-color OH-LIF thermometry. For the OH-LIF and thermometry measurements, a stainless-steel disk mounted above the burner surface stabilized the flames at pressures up to 10 bar.

Approximately 10 ns Nd:YAG laser pulses at 283.305 nm excited the Q1(7) rotational line of the OH A2Σ+–X2Π (1,0) band. Fluorescence was detected from the A–X (1,1) and (0,0) bands.

The OH-LIF signal varied linearly with laser energy within the investigated range. Increasing pressure from 1 to 10 bar produced a nonlinear reduction in signal. Collisional-quenching corrections explained only part of that loss, indicating that laser-beam absorption, signal trapping and related high-pressure effects must also be considered for quantitative interpretation.

The measured OH excitation spectrum agreed well with LIFBASE predictions. Equivalence-ratio scans at different pressures were consistent with Cantera equilibrium calculations. Two-dimensional OH distributions and two-color OH-LIF temperature fields also agreed qualitatively with ANSYS Fluent flame simulations.

Technical contribution

The work establishes a documented experimental platform that combines elevated-pressure operation, optical access, high-speed imaging, laser diagnostics and numerical comparison. It therefore supports diagnostic-method development as well as controlled studies of pressure-dependent flame chemistry and stability.

A central contribution is the explicit identification of high-pressure limitations in OH-LIF signal quantification. The study shows that collisional quenching alone is insufficient to explain the observed pressure dependence and that optical attenuation and signal reabsorption must be considered.

Diagnostic and modelling framework

  • laboratory-scale, optically accessible high-pressure burner;
  • premixed methane–air flames;
  • kHz-rate OH* and CH* chemiluminescence imaging;
  • OH laser-induced fluorescence imaging;
  • two-color OH-LIF thermometry;
  • flame stabilization up to 10 bar using a stainless-steel disk;
  • comparison of excitation spectra with LIFBASE;
  • equilibrium comparisons using Cantera;
  • qualitative comparison of OH and temperature fields with ANSYS Fluent simulations.

Scope and application boundary

The facility was characterized for the reported premixed methane–air configurations and demonstrated up to 10 bar for the OH-LIF and thermometry measurements. This operating range should not be presented as equivalent to the full 30–50 bar pressure range cited for modern gas-turbine combustors and turbine inlets.

The OH-concentration and temperature comparisons with ANSYS Fluent were qualitative. They do not constitute a complete quantitative validation of the numerical model or of absolute OH concentration.

Quantitative OH-LIF at elevated pressure requires treatment of collisional quenching, spectral broadening, laser-sheet absorption, fluorescence trapping, detector response and spatially varying temperature and composition. Neglecting these effects can distort inferred concentration and temperature fields.

The stainless-steel stabilization disk is part of the experimental boundary condition. Its influence on heat loss, recirculation, flame shape and local transport should be considered when transferring the findings to another burner or interpreting comparisons with an unstabilized flame.

Publisher access

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Rights and repository note

Springer Nature states that exclusive rights to the article are held under the applicable publishing agreement and that self-archiving of an accepted-manuscript version is governed by that agreement and applicable law.

A local PDF link has therefore not been included on this page because the version and self-archiving status of the existing repository file have not yet been verified. It can be restored after confirming that the hosted file is an author version permitted for public deposit.

Citation

Swain, W., Wang, Y., Parajuli, P., Hay, M., Saylam, A., Dreier, T., Schulz, C., & Kulatilaka, W. (2023). Characterization of a high-pressure flame facility using high-speed chemiluminescence and OH LIF imaging. Experiments in Fluids, 64, Article 71. https://doi.org/10.1007/s00348-023-03611-0