Investigation of Single-Jet Combustor Near Lean Blowout Conditions Using Flamelet-Generated Manifold Combustion Model and Detailed Chemistry

Abstract

Numerical simulation results of a single-jet premixed combustion system at atmospheric pressure are compared against comprehensive particle image velocimetry (PIV) flow measurements and Raman scattering temperature measurements for natural gas and hydrogen fuels. The simulations were performed on hexahedral meshes with 1–5 × 106 elements. Reynolds-averaged Navier–Stokes (RANS) calculations were carried out with the k–ε realizable turbulence model. Combustion was modeled using the flamelet-generated manifold model (FGM) and detailed chemistry. Both the flame position and flame liftoff predicted by the FGM were in reasonable agreement with experiments for both fuels and showed little sensitivity to heat transfer or radiation modeling. The detailed chemistry calculation predicts the temperature gradients along the jet centerline accurately and compares very closely with the Raman scattering measurements. The much closer agreement of the jet axial velocity and temperature profiles with experimental values, coupled with the significantly protracted presence of intermediates in the detailed chemistry predictions, indicates that the impact of nonequilibrium intermediates on very lean natural gas flames is significant.

Hydrogen-Enriched Natural Gas Co-Firing: A Comparison of FGM and EDC Models

“…Zghal et al [6] applied the FGM and EDC to model a hydrogen-fueled micromix burner and concluded that both FGM and EDC can capture the features of micro-mix flame well. Patil et al [8] compared the performance of EDC and FGM in evaluating a CH4-fuelled single-jet flame near lean blowout conditions; the study confirmed that EDC yielded closer agreement with measured results than FGM in capturing lean flame behaviours, as shown in Figure 1. This figure shows that with increasing centerline distance away from the jet flame, the FGM model generally poorly predicts the temperature profiles, compared to the EDC.…”

“…The GRI-mech3.0 [25] is a chemistry kinetic mechanism widely used to model natural gas flames. Its use in CFD is proposed by several works including Refs [8][10] [26]. When modelling the co-firing of CH4/H2 blends, it is generally recommended to use the GRI-3.0 chemical kinetic mechanism for low hydrogen concentrations (<50%).…”