EFFECTS OF TURBULENCE MODELS ON PREDICTION ACCURACY OF THERMAL NOx EMISSIONS IN A MICROMIX COMBUSTOR

S. Tamang; H. Park

doi:10.6112/kscfe.2026.31.1.054

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Original Article

EFFECTS OF TURBULENCE MODELS ON PREDICTION ACCURACY OF THERMAL NOx EMISSIONS IN A MICROMIX COMBUSTOR 마이크로믹스 수소 연소기에서 난류모델이 열적 NOx 발생량 예측 정확도에 미치는 영향

31 March 2026. pp. 54-64

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Abstract

In this study, we investigated the effects of turbulence model selection and equivalence ratio on the internal flow field, flame temperature distribution, and thermal NOx emissions in a single-nozzle micromix combustor. The combustor was designed to accelerate the oxidizer flow through an air-guide passage, while hydrogen was injected perpendicularly through a dedicated fuel nozzle. This configuration promotes microscale fuel-air mixing within the shear-layer region generated by the inner and outer vortex pair. To achieve these objectives, three-dimensional RANS simulations were performed using the commercial numerical code ANSYS Fluent 25R2. Combustion was modeled using a finite-rate/eddy-dissipation approach, and thermal NOx was quantified at the outlet and normalized to 15% O₂ (dry). The results demonstrate that the choice of turbulence model strongly affects the oxidizer flow field, leading to either strengthened or weakened vortex structures and a corresponding change in the high-temperature region along the shear layer. The realizable k-ε model predicts the strongest recirculation and the highest local velocities. Thermal NOx increases with equivalence ratio and reaches a maximum value at ER = 0.47. Among the tested models, the realizable k-ε model shows the highest agreement with the experimental data. Consequently, turbulence model selection significantly affects the predicted temperature field and NOx trend and should therefore be treated as a key factor in micromix combustor design assessments.

Keywords

Hydrogen

Combustion

Vortex

NOx emission

키워드

수소

연소

와류

NOx 배출

수치해석

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Information

Publisher :Korean Society for Computational Fluids Engineering
Publisher(Ko) :한국전산유체공학회
Journal Title :Journal of Computational Fluids Engineering
Journal Title(Ko) :한국전산유체공학회지
Volume : 31
No :1
Pages :54-64
Received Date : 2026-01-30
Revised Date : 2026-03-24
Accepted Date : 2026-03-26
DOI :https://doi.org/10.6112/kscfe.2026.31.1.054

Journal of Computational Fluids Engineering ISSN:1598-6071(Print) 3022-6252(Online) 한국전산유체공학회지

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