Eddy Dissipation Concept Research Articles

Two-zone subgrid combustion model for large eddy simulations of buoyant diffusion flames

This work presents the development of a novel two-zone subgrid combustion model (SCM) recently designed to incorporate the finite-rate kinetics in the large eddy simulations of buoyant turbulent diffusion flames in which turbulence might not be fully developed. The reaction rate is evaluated as the mass-weighted average of contributions by the higher-temperature flamelet zone and the lower-temperature surrounding. The volume fraction of the flamelet zone and the time scale responsible for the inter-zone transfer are determined by the expected thickness of the laminar diffusion flamelet existing in the grid cell, and by wrinkling its surface by the unresolved turbulent eddies. This approach is applicable to an arbitrary level of turbulence (quantified by the subgrid Reynolds number) thereby overcoming the limitation of the conventional eddy dissipation concept formulated for the high-Re flames. Advancing the previous study [1], the flamelet status at every time step is evaluated by solving transient equations of heat and mass transfer between the subgrid zones. Effective kinetic parameters for the simplified global reaction of fuel oxidation are derived from experimental data for autoignition delay in methane-air and n-heptane-air mixtures and are shown to capture transition from the low- to high-temperature measurement datasets including the NTC (negative temperature coefficient) interval. With these kinetic parameters, the SCM is validated against the measurements in the unconfined methane-air flame produced by the UMD line burner and then applied to predict the development and extinction of the heptane-air flame in an under-ventilated enclosure. In the first case, flame extinction is predicted at the oxygen concentrations consistent with the experimental values. In the second scenario, global low-frequency oscillations of the heat release rate are predicted prior to flame extinction.

Multi-Element Gaseous Methane–Oxygen Rocket Combustor Optimization for Modern Space-Flight Technology

In the realm of reusable rocket technology, the methane–oxygen propellant combination has gained prevalence in recent years. However, understanding of design parameters affecting the combustion performance of a methane–oxygen combustor is currently limited. The present study proposes a novel analytical and computational approach to design and optimize a combustor. The design of a seven-shear coaxial injector-based combustion chamber is optimized using an in-house developed code line with the aim of minimizing chamber length while preserving chamber performance. Numerical simulations are then carried out to ensure complete combustion within the chamber. Methane–oxygen reactions are modeled using laminar finite-rate and eddy dissipation concept models. An optimized design for the combustion chamber shows maximum characteristic velocity and optimal chamber length near the oxygen-to-fuel mass ratio of 2. The computational study shows that the eddy dissipation concept model can accurately capture the effect of turbulent mixing on gaseous methane–oxygen reactions. The eddy dissipation concept model yielded notable differences in flame characteristics compared to the laminar finite-rate model. The study indicates a need to optimize injector configuration. An optimized injector configuration is proposed by varying its geometric parameters, which exhibits substantial improvement in combustion performance compared to the initial configuration, utilizing practical recess, divergence, and an increased velocity ratio.

Numerical study of the effect of ultrasound waves on the turbulent flow with chemical reaction

In this study, a numerical analysis of turbulent flow in a combustion chamber with a Reynolds number of 16700 was conducted, focusing on the application of a 20 kHz ultrasound wave from a bowl-shaped diffusion source for 1 s to reduce process temperature within 5 ms. The study employed the k-ω model, with turbulence-chemistry interaction modeled using the eddy dissipation concept to achieve this. Additionally, the relocation of nozzles was explored, increasing CO2 combustion from 0.31 to 0.34 by decreasing the distance between them. The most optimal distance for locating the nozzles was identified as Di 0.0.1 (Di = 4.58 mm), which exhibited a higher burning rate and increased velocity and temperature during the process. Furthermore, a spray angle of 45° was determined as the optimal angle for minimizing fuel film on the walls and improving combustion. The application of ultrasound waves facilitated the transfer of flame concentration from the walls to the chamber's center, effectively reducing unburnt hydrocarbons on the walls. Notably, the propagation of ultrasound waves significantly accelerated the combustion process by 0.5 ms, setting this study apart from previous investigations.

Cavity effects on spontaneous ignition of pressurized hydrogen jets

The release of pressurized hydrogen jets can lead to spontaneous ignition, which poses a major challenge to the safe utilization of hydrogen energy. Previous studies have primarily focused on the spontaneous ignition of pressurized hydrogen released into tubes. However, in real industrial scenarios, pressurized hydrogen is usually released into the atmosphere or a complex equipment environment. Therefore, the effect of obstacles on spontaneous ignition needs to be considered. In this study, the spontaneous ignition of sudden releases of pressurized hydrogen entering various cavity shapes was modeled using the standard k-ω turbulence model, the eddy dissipation concept (EDC) model and a detailed 21-step chemistry model. The effects of the cavities on the jet flow fields and the spontaneous ignition were analyzed for various cavity shapes and release pressures. For the pressures considered in this study, the cylindrical cavity did not lead to ignition. The highest hydrogen jet temperature occurred in the contact region due to the shock wave reflection, after which spontaneous ignition could not occur due to the flow divergence. The pressurized hydrogen entering hemispherical and conical cavities enhanced the hydrogen-air mixing which led to combustible regions and the formation of multidimensional shock waves, which significantly increased the spontaneous ignition probability. The cavities created a high-temperature region inside the cavity that experienced ignition but the flames did not spread out of the cavity. The conical cavity produced lower flame temperatures than the hemispherical cavity but prolonged the flame lifetime. Higher initial hydrogen release pressures resulted in more violent multidimensional shock wave interactions and higher contact surface temperatures, which lead to earlier ignition times but with little impact on the initial location of the spontaneous ignition. The results of this study provide a scientific foundation for hydrogen safety codes, safe equipment designs and the development of industry codes and standards.

Hydrogen, methane and one of their fuel blends combustion: CFD analysis and numerical-experimental comparisons of fixed and mobile applications

The capabilities of Computational Fluid Dynamics (CFD) coupled with detailed chemistry simulations are examined in both steady jet diffusion flames and in an internal combustion engine case fuelled with hydrogen. Different approaches to turbulence-chemistry interaction such as the “Laminar Flame Concept” the “Eddy Dissipation Concept” and the “Turbulent Flame Speed Closure” are considered and tested. The results are compared with the experimental data available. Concerning the jet diffusion flames, the combustion processes of hydrogen, methane and one of their fuel blends are investigated on two burner geometries. Different sensitivities (i.e. mesh, turbulence model, turbulent Schmidt number, chemical mechanism) are performed. The study demonstrates that despite the burner geometry considered and the chemical composition of the fuel, the Complex Chemistry with “Eddy Dissipation Concept” is the model that better describes the behaviour of the turbulent flames. On the other hand, the “Laminar Flame Concept” sub-model is characterized by an higher fuel consumption rate, which causes an overestimation of the temperature peak. As for the in-cylinder unsteady simulations, the hydrogen combustion process is better described by the “Turbulent Flame Speed Closure” sub-model, which, unlike the other two, requires the specification of both laminar and turbulent flame speed. Despite different variations being considered, the “Laminar Flame Concept” adoption leads to an unphysically high burning rate, while the Eddy Dissipation Concept sub-model is characterized by an underestimation of the apparent heat release rate, and thus of the pressure peak inside the combustion chamber.

Colourless distributed combustion effects on a pre‐mixed coke oven gas flame

AbstractFuels consisting of high hydrogen concentration can be consumed under colourless distributed combustion (CDC) to suppress flashback tendency in premixed conditions. Higher NOX challenges can also be overcome through CDC. For those purposes, coke oven gas was consumed under CDC within the scope of this study. To achieve CDC, or diluents were introduced into the oxidizer so that oxygen concentration in the oxidizer would be decreased from 21% O2 to its lean blow‐off limits. Excess air ratios were determined as λ = 1.2 and λ = 1.5 along with a thermal power of 10 kW under premixed conditions. A commercial computational fluid dynamics code was used to predict temperature distribution and , CO, and emissions. 162‐step reactions created with GRI‐Mech 3.0 chemical kinetics was integrated to the eddy dissipation concept combustion model. The temperature and profiles predicted were compared with the experimental results. Consistency was achieved at ~95% for temperature profiles, and almost 100% for profiles between the measured and the predicted ones. According to the results, it is concluded that a more homogeneous temperature distribution with the ~21% decrease in the maximum temperature was observed, and there was about 96% decrease in level. It was also demonstrated that using as a diluent is more effective in terms of temperature distribution over the combustor and reduction, while dilution with is more effective in terms about 70% in decrease on CO.

Characterizing pulverized coal combustion for high-ash content Indian coal

ABSTRACT The present study performs three-dimensional (3D) numerical simulations of coal combustion of four samples with varying ash content in a drop tube furnace (DTF) to mimic the particle heating rates observed in industrial furnaces. The numerical framework adopted is validated with prior experimental and simulation results using a 3D cylindrical geometry and a very good match is obtained for the axial temperature distribution and particle burnout rate. The combustion performance of coal samples with varying ash contents of 2.3, 16.6, 24.1, and 37.2 wt%, is explored through temperature profiles, burnout rates, particle tracking, and mass fractions of various products of combustion. A user-defined function is used to specify the 14 species, 10-step solid particle combustion with a modified eddy dissipation concept model for volatile combustion. The range of ash content considered is for Indian coal which has a high degree of heterogeneity, making the evaluation of its combustion performance, a challenge. The present work aims to provide benchmark set of results showing the evolution of the evaporated, charred, and volatile mass for the three ash contents, which has not been attempted before. It is found that the high-ash content Indian coal samples have a tendency to produce less . A reduction in the is obtained for the coal sample with ash compared to that with ash. The results suggest that the combustion performance is enhanced when the ash content falls within an optimum range of .

A comparative study of combustion models for simulating partially premixed swirling natural gas flames

Combustion models are important for simulating chemical reaction properties and the turbulence-chemistry interaction (TCI) in combustion. However, little attention has been paid to the temperature/species distributions/velocity flow fields predicted by different combustion models and their requirements for mesh resolution. In the present work, a partially premixed swirling natural gas flame was separately simulated by two commonly-used combustion models in Reynolds-Averaged-Numerical-Simulation (RANS) simulations: the flamelet generated manifold (FGM) model and the eddy dissipation concept (EDC) model. It is found that the EDC model requires a higher quality of mesh than the FGM model from the temperature and species distributions perspective. It is possible for the EDC model to overpredict temperature, however, such a problem can be solved by improving the mesh quality. The combustion models do not differ obviously for the mesh refinement for flow fields. The further analysis find that the EDC model brings forward the reaction location (11 mm upstream than the FGM model). The weakened turbulence mixing and early chemical reactions make the EDC model derive discrepancies with measured values, resulting from the variations between its modelling principles and actual applications in the software ANSYS Fluent. The low turbulence viscosity makes the EDC model flame thicker. Overall, the FGM model showed better suitability and accuracy for such a partially-premixed swirling natural gas flame. This work connects the two common combustion models and partially premixed swirling flame characteristics in the RANS simulations, and highlights the effects on the temperature/species concentration/turbulence flow fields, in concerns of mesh resolution and reaction properties rather than sole applications, which can provide foundation for subsequent researchers.

Soot Modeling in Large Eddy Simulation of Turbulent Buoyant Flames Using the Laminar Smoke Point and the Eddy Dissipation Concept

ABSTRACT The paper presents a comprehensive set of Large Eddy Simulations (LES) of turbulent diffusion buoyant flames with a focus on soot modeling. Combustion modeling is based on the Eddy Dissipation Model (EDM) with an infinitely fast chemistry approach. Soot formation and oxidation are modeled with finite-rate chemistry based on the Laminar Smoke Point (LSP) concept. A turbulence-soot interaction model is proposed based on the Eddy Dissipation Concept (EDC) to close the chemical sink/source term for soot. A novel aspect of the modeling is the hybrid EDC formulation, where the mean chemical source term is a weighted average of a laminar term and a turbulent term, based on the local turbulent Reynolds number. The correct limiting behavior in the laminar regime is demonstrated for a laminar ethylene flame. Improvements in soot predictions near the fuel injection are obtained for a 13.7 cm-diameter turbulent ethylene flame and a 30 cm-diameter heptane flame. Additionally, the influence of the combustion model on soot predictions is carefully examined, especially with respect to the mixing time scale formulation and the related influence of the cell size (used as filter width in LES). A proposed dynamic model allows obtaining improved results even in under-resolved simulations and mitigating mesh sensitivity for soot predictions.

Optimizing biomass combustion in a 130 t/h grate boiler: Assessing gas-phase reaction models and primary air distribution strategies

Grate-firing technology is widely used for biomass combustion for heat and power production due to its good fuel flexibility. However, grate boilers often suffer from high unburnout, low efficiency, and high emissions, and require optimization to improve their performance. The distribution of primary air along the grate length significantly affects combustion and pollutant formation behaviors in the furnace; however, this effect is often under-investigated and poorly quantified. In this study, combustion of corn stover in a 130 t/h grate boiler is investigated experimentally and numerically. To establish a reliable baseline computational fluid dynamics (CFD) model and provide valuable reference for modeling and optimizing this industrial grate boiler, this study first investigates the applicability of the commonly used gas-phase reaction models. The finite rate/eddy dissipation model is found to outperform other gas-phase reaction models such as eddy dissipation model and eddy dissipation concept, which well predicts the temperature and shape of the flame in both the kinetics-controlled primary combustion zone and the diffusion-controlled burnout zone and shows the best agreement with the measured and site observations. Then, the study simulates and quantifies the effects of different primary air distribution modes (uniform, staged and refined-staged) on combustion performance of the boiler. Compared with the uniform primary air distribution, both the staged and refined-staged primary air distribution show an obvious increase in the char burnout ratio, from 76.5 % to 87.8 % and 95.5 %, respectively. Furthermore, the CO concentration at the furnace outlet is remarkably reduced, from 3178 ppm to 2766 ppm and 1917 ppm, respectively. This demonstrates that reasonable air supply in the latter two primary air distribution cases facilitates complete combustion in both the fuel-bed and freeboard. Moreover, in the latter two cases, the temperature distribution in the freeboard becomes more uniform, and the local oxygen-rich regions are eliminated. These are beneficial in suppressing the NO formation, as the emission of which decreases from 172 mg/m3 (at 11 % O2) to 161 mg/m3 and 156 mg/m3, respectively. This work provides important theoretical guidance for the accurate modeling and optimization of grate-firing boilers as well as the design of new grate boilers.

Computational study of a high-pressure hydrogen storage tank explosion at different heights from the ground

A computational study was carried out to investigate the explosion of a 35-MPa, 72.4-L high-pressure hydrogen storage tank at different heights from the ground. The numerical simulations were carried out using OpenFOAM computational fluid dynamics code. The numerical simulation incorporates a k−ω shear stress transport turbulence model and an eddy dissipation concept combustion model with a one-step finite rate reaction. The prediction performance of the numerical approach was validated based on experimental results obtained from previous studies. The hydrogen tank explosion was investigated at different heights (h; 0.0, 0.2, 0.5, 0.8, and 1.0 m) from the ground and at h = 0.2 m from the ground with θ = 65°). The numerical predictions showed that tank height and position significantly affect the blast overpressure strength and propagation. The reflected pressure magnitude increased as the tank height decreased with respect to ground level. At farther distances, the explosion scenario of h = 0.2 m and θ = 65° showed stronger maximum overpressure and impulse hazards than the other height settings. The difference in maximum overpressure magnitude between the different explosion scenarios was insignificant at 4 m from the tank. Hydrogen gas auto-ignites closer to the ground, due to the compression effect attributed to the Mach stem phenomenon. Our results showed that blast effects in the radial direction are more hazardous than those in the axial direction.

On the subgrid dissipation concept for large eddy simulation of turbulent combustion

A new subgrid turbulent combustion model for LES is derived based on the eddy dissipation concept (EDC). To be consistent with the LES framework, the relationship between the subgrid quantities and the fine structure ones is built from the unresolved part of the energy cascade, hence the subgrid dissipation concept (SDC). The fine structure quantities are directly computed using the subgrid scale ones. Resolving local laminar flame structures is allowed if the grid resolution permits. The model is examined using premixed piloted jet flames and non-premixed swirl flame. Satisfactory predictions from the SDC model are obtained in the test cases, showing improvements with respect to the standard EDC model. The new SDC model is relatively insensitive to the grid resolution.

Reynolds number-based global modification of EDC constants and simulation of a syngas and a piloted CH4/air flames

The Eddy Dissipation Concept (EDC), as a promising flame prediction model, is reviewed comprehensively. Instead of strong modifications of the standard EDC constants to fit experiments, a modification method of the EDC constants based on the fuel jet Reynolds number is presented in this work and used to predict a simple jet nonpremixed syngas Sandia Flame CHN–B and a piloted CH4/air partially premixed Sandia Flame D. Compared with the experiments, the predictions show the two flames are properly reproduced with the modified EDC constants. Some over-predictions might be attributed to the under-estimation of turbulence. The microscale and the macroscale Damköhler numbers are presented showing decreasing trends with the increased Reynolds number. Three clear combustion regions in the two flames are firstly identified from the results of the net reaction rate of OH. The reaction heat in the fuel-rich region is found larger than that in the fuel-lean region for Flame D. The contours of the net reaction rate of OH show a stronger reaction region in the fuel-lean side for Flame CHN–B and in the fuel-rich side for Flame D. The predictions with the modified EDC constants agree with the experiments better than those with the standard EDC constants.

Numerical Modeling of Aircraft Fire: Postcrash Fire

The Fire Dynamics Simulator (FDS) model was utilized in this study to replicate a full-scale aircraft postcrash experiment conducted within the C-133 test facility by the Federal Aviation Administration. FDS is a computational fire field model that incorporates submodels for soot formation, pyrolysis, and thermal radiation transport. It solves three-dimensional time-dependent Navier–Stokes equations and is grounded in the large-eddy simulation approach and the eddy dissipation concept, serving as turbulence and combustion models. The obtained results, including the heat release rate and temperature, were validated against experimental data and compared with earlier prediction studies employing different turbulence and combustion models. The results from this simulation closely align with the experiment’s findings. The impact of fire-blocking layers and carry-on baggage on interior material was examined. Moreover, two boundary conditions were imposed on the fuselage structure: 1) the adiabatic wall, and 2) heat loss within the wall. Both the fire-blocking layers and the adiabatic boundary condition played a significant role in the flashover occurrence. The large-eddy simulation and eddy dissipation concept approaches have demonstrated a reliable ability to predict flashover and general fire properties to a considerable extent.

Comparative study on homogeneous NO-reburning in flameless and swirl flame combustion

NO-reburning technology can effectively decrease NOx emissions during combustion. Despite extensive studies have been conducted on NO reburning under traditional combustion, homogeneous NO-reburning characteristics have not been systematically examined in flameless combustion (FLC). This study performs a systematic comparative investigation of homogeneous NO-reburning for the first time via experiments and simulations in a 20-kW furnace. The influences of combustion mode, air-preheating temperature (Ta), and equivalence ratio (Φ) are studied in detail. The experimental results show that FLC can improve NO-reduction efficiency by more than 35% compared to swirl flame combustion (SFC). Moreover, the results also show that reducing Ta from 723 K to 573 K can enhance NO-reburning during FLC, while the NO-reburning is insensitive to Φ in the range of 0.65–0.89. Furthermore, a detailed numerical simulation that couples the eddy-dissipation concept model and a well-verified skeletal mechanism for NO-reburning is validated and performed, to further reveal the reduction pathways of NO. By combining flameless combustion with NO-reburning, this study confirms the preponderance of flameless combustion under low-temperature air conditions (Ta ≤ 573 K) for considerable NO reduction by reburning. The results offer novel fundamental insights into the homogeneous NO-reburning characteristics.

The reactor-based perspective on finite-rate chemistry in turbulent reacting flows: A review from traditional to low-emission combustion

In flames, turbulence can either limit or enhance combustion efficiency by means of strain and mixing. The interactions between turbulent motions and chemistry are crucial to the behaviour of combustion processes. In particular, it is essential to correctly capture non-equilibrium phenomena such as localised ignition and extinction to faithfully predict pollutant formation. Reactor-based combustion models — such as the Eddy Dissipation Concept (EDC) or Partially Stirred Reactor (PaSR) — may account for turbulence-chemistry interactions at an affordable computational cost by calculating combustion rates relying upon canonical reactors of small fluid size and timescale. The models may include multiscale mixing, detailed chemical kinetic schemes and high-fidelity multispecies diffusion treatments. Although originally derived for conventional, highly turbulent combustion, numerous recent efforts have sought to generalise beyond simple empirical correlations using more sophisticated relationships. More recent models incorporate the estimation of scales based on local variables such as turbulent Reynolds and Damköhler numbers, phenomenological descriptions of turbulence based on fractal theory or specific events such as extinction. These modifications significantly broaden the effective range of operating conditions and combustion regimes these models can be applied to, as in the particular case of Moderate or Intense Low-oxygen Dilution (MILD) combustion. MILD combustion is renown for its ability to deliver appealing features such as abated pollutant emissions, elevated thermal efficiency and fuel flexibility. This review describes the development and current state-of-the-art in finite-rate, reactor-based combustion approaches. Recently investigated model improvements and adaptations will be discussed, with specific focus on the MILD combustion regime. Finally, to bridge the gap between laboratory-scale canonical burners and industrial combustion systems, the current directions and the future outlook for development are discussed.

Numerical investigation on the combustion characteristics of powder fuel under different regulation parameters

A comprehensive numerical study is undertaken to investigate the operating feature in a powder fueled scramjet combustor. The effect of regulation parameters on the flow field and combustion mechanism is examined systematically. The numerical simulation method is developed for multi-species gas-solid two-phase turbulent combustion in the Euler-Lagrange frame. The particle surface reaction model and the Eddy-dissipation Concept model are utilized for powder fuel combustion. The combustor flow field, flame structure, and species distribution in the powder fueled scramjet combustor are revealed in detail. The numerical simulation results show that the combustion organization scheme of tandem double-cavity can provide an excellent flame stabilization effect. The powder fuel achieves continuous combustion and sufficient release heat in the supersonic airflow. The combustion flow field features and flame distribution are strongly influenced by the transport solid-gas ratio and the equivalent ratio. The increase of both regulation parameters improves the combustion efficiency of powder fuel in the region from the injection hole to the downstream cavity. Nevertheless, the large equivalent ratio significantly leads to higher total pressure losses in the combustor.

Numerical study of the impact of the EDC formulation and finite-rate chemistry mechanisms in CFD simulations of fire plumes

CFD simulations are presented for an in-depth study on different formulations (including implementation details) of the Eddy Dissipation Concept (EDC) turbulent combustion model, with infinitely fast chemistry as well as finite-rate chemistry with different reaction mechanisms. A turbulent line burner and a gaseous pool fire are chosen as first step in an extensive validation campaign for large eddy simulations of this kind, performed with OpenFOAM v1912. Artificial flame anchoring is necessary to establish a burning flame with finite-rate chemistry. Differences in mean temperatures, and the resulting flow fields, as obtained with the different formulations of the EDC combustion model, are explained by the impact of the reaction rates. CO is discussed as the most important of minor species as well. It is demonstrated that both the formulation of EDC and the choice of the chemistry mechanism can have a significant impact when the CFD mesh is not sufficiently fine, even though the flames studied are unsuppressed. This can lead to significant deviations from experimental data. This is a point of attention for future work, focusing on extinction and re-ignition phenomena.

Numerical Exploration of Staged Hydrogen Combustion in A Strut Based Scramjet Combustor

Scramjet combustor with fuel injection from strut and wall is numerically simulated using three-dimensional Navier Stokes equations along with k - ε turbulence model. Turbulence - chemistry interaction is modeled through Eddy Dissipation Concept (EDC) based on infinitely fast rate kinetics. The simulations captured all the essential features of flow field for various combinations of fuel injections from the strut and the wall. The computed surface pressures match very well with the experimental values for both reacting and non-reacting cases. Performance parameters are evaluated from the computed flow variables. It was found that more fuel could be injected in the scramjet combustor through staged injection without inlet - combustor interaction.

Experimental and numerical study on the combustion and infrared radiation characteristics of Mg/PTFE/Viton pyrotechnic compositions

The combustion process of Mg/PTFE/Viton-based pyrotechnics exhibits a complex multiphase flow phenomenon. However, the influence mechanism of metal particles undergoing dynamic diffusion combustion in the flow field on the infrared radiation output characteristics has not yet been elucidated. Systematic experiments and numerical simulations are performed with the combustion and infrared radiation behaviors of the pyrotechnic compositions. A small-scale sealed combustion experiment platform is specially manufactured to mimic the actual ambient pressure at different cruise altitudes. An infrared thermal imager and an infrared thermometer are adopted cooperatively to diagnose the burning process. The Euler-Langrangian method is applied to mathematically describe the gas–solid two-phase interaction in the combustion flow field, and the Eddy Dissipation Concept (EDC) combustion model is employed to simulate the coupling effect of turbulence and chemical reaction in the gas-phase reaction zone. The verified Source Six-Flux (SSF) method based in-house code solves the infrared radiative transfer equation integrating the emission, absorption and scattering effects of participating media. The comparisons with the experimental results demonstrate that the computational model involving heterogeneous reactions established in this paper better approximates the realistic situation. The results reveal that the infrared radiation output capability of dispersed combustion particles in the 2.0–5.5 μm band surpasses that of high-temperature gas molecules under different environmental pressures. The infrared radiation magnitude of both the gaseous phase and the particulate phase decrease significantly with decreasing pressure. The thermal radiation of combustion particles is mainly concentrated in the near- to mid-infrared band, while its emission in the far-infrared band is relatively weak. These scientific findings provide conducive insights for lucubrating the infrared radiation mechanism of pyrotechnics under negative pressure environments, and assist in further promoting the application of MTV pyrotechnics in the field of aerospace.