open access publication

Article, 2024

Impact of pilot flame and hydrogen enrichment on turbulent methane/hydrogen/air swirling premixed flames in a model gas turbine combustor

Experimental Thermal and Fluid Science, ISSN 1879-2286, 0894-1777, Volume 152, Page 111124, 10.1016/j.expthermflusci.2023.111124

Contributors

Pignatelli, Francesco 0000-0003-0741-7418 [1] Sanned, David 0000-0002-2213-3512 [1] Derafshzan, Saeed [1] Szasz, Robert-Zoltan 0000-0001-5736-3126 [1] Bai, Xue-Song 0000-0002-0438-5599 [1] Richter, Mattias 0000-0002-9914-7218 [1] Ehn, Andreas 0000-0002-3716-8822 [1] Lörstad, Daniel [2] Petersson, Per Fredrik 0000-0001-6697-0171 [3] Subash, Arman Ahamed 0000-0002-0259-2009 (Corresponding author) [1]

Affiliations

  1. [1] Lund University
    2. [NORA names: Sweden; Europe, EU; Nordic; OECD];
  2. [2] Siemens (Sweden)
    3. [NORA names: Sweden; Europe, EU; Nordic; OECD];
  3. [3] Dantec Dynamics A/S, Skovlunde, Denmark
    4. [NORA names: Other Companies; Private Research; Denmark; Europe, EU; Nordic; OECD]

Abstract

This work investigates the impact of pilot flame and fuel composition on the structures and stabilization of swirling turbulent premixed methane/hydrogen/air flames in a lab-scale gas turbine model combustor. Simultaneous measurements of the velocity field and OH radicals distribution in the combustor were conducted using particle imaging velocimetry (PIV) and planar laser-induced fluorescence (PLIF) methods, respectively. Flames under stable and close to lean blow-off (LBO) conditions were studied for two fuel mixtures, with a hydrogen mole ratio of 0 and 50 % in the hydrogen/methane mixture, respectively. The studied flames were at a constant Reynolds number of 20,000 with different equivalence ratios. Two pilot-to-global fuel ratios were investigated (2 % and 6 %) while keeping the pilot-to-global air ratio constant at 2 %. Data for non-piloted flames were also acquired for comparison. The pilot flames were shown to extend the operability range. The LBO equivalence ratio of the main flame decreased with increasing fuel mass flow rate in the pilot flames due to the increased amount of hot gases with high concentrations of OH radicals in the outer recirculation zone (ORZ), which significantly enhanced the stabilization of the main flame. The stable flame reaction zone was in the high-speed shear layer between the ORZ and the inner recirculation zone (IRZ). When approaching LBO, the reaction zone was pushed downstream to the IRZ and subsequently decreased the size of IRZ, indicating a strong flow/flame interaction. Hydrogen enrichment was shown to reduce the LBO equivalence ratio. When close to LBO, the OH radicals in the hydrogen-enriched flames were observed in isolated pockets due to differential diffusion, which enhanced resilience to LBO. The flame front curvature, mean progress variable, and flame surface density were calculated from the acquired OH-PLIF data to quantify the impact of fuel composition and pilot flames on the flame structures.

Keywords

OH radical distribution, OH radicals, OH-PLIF data, Reynolds number, amount of hot gas, blow-off, combustor, comparison, composition, concentration, concentration of OH radicals, constant, constant Reynolds number, curvature, data, density, differential diffusion, diffusion, distribution, enhance resilience, enrichment, equivalence, equivalence ratio, field, flame, flame front curvature, flame reaction zone, flame structure, flame surface density, flow rate, fluorescence, front curvature, fuel, fuel composition, fuel mass flow rate, fuel mixture, fuel ratio, gas, gas turbine combustor, gas turbine model combustor, high-speed shear layers, hot gas, hydrogen, hydrogen enrichment, hydrogen-enriched flames, hydrogen/methane, hydrogen/methane mixtures, image velocimetry, impact, impact of fuel composition, increasing amount, inner recirculation zone, interaction, laser-induced fluorescence, layer, lean blow-off, mass flow rate, measurements, methane/hydrogen/air, mixtures, model combustor, model gas turbine combustor, mole ratio, number, operating range, operation, outer recirculation zone, particle image velocimetry, particles, pilot, pilot flame, planar laser-induced fluorescence, premixed flames, progression, radical distribution, radicals, range, rate, ratio, ratio constant, reaction, reaction zone, recirculation zone, resilience, shear layer, simultaneous measurement, size, stability, structure, surface density, turbine combustor, velocimetry, velocity, velocity field, zone

Funders

  • Swedish Energy Agency
  • Siemens (Germany)
  • Knut and Alice Wallenberg Foundation
  • Swedish Research Council

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