Year: 2026
Type: preprint
Abstract: Pollutant predictions in turbulent diffusion flames depend on how mixing, chemistry and their coupling are modelled. Using the Brookes–Moss experiments as reference, this study assesses how the Reynolds-averaged Navier–Stokes (RANS) turbulence closure, the chemical-kinetic scheme and the turbulence intensity of the air co-flow affect the computed structure, nitric oxide (NO) and soot of an enclosed methane jet flame at a Reynolds number of 5000. Steady axisymmetric simulations used the eddy-dissipation model, thermal and prompt NO post-processing and the Moss–Brookes soot model. The measured mixture fraction and the fast-chemistry limit were combined to bound the predicted fuel mass fraction. Of the closures tested ( k – ε , k – ω and a Reynolds-stress model, RSM), the RSM lowered the mean absolute percentage error of the centreline temperature from 30.1% to 15.9%. Replacing the one-step scheme by a 16-step augmented reduced mechanism lowered the fuel-decay error from 56.6% to 9.5%, a larger gain than that obtained by changing the closure. Raising the co-flow turbulence intensity from 20% to 80% reduced the peak NO from 183 to 168 ppm (− 8.4%) and the peak soot volume fraction by 43%. Centreline soot levels agreed with the measurements within 7%, although the radial soot extent was under-predicted.
Source: Research Square
Institution: Maharaja Sayajirao University of Baroda
Language: English
Subfield: Computational Mechanics
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7225614053