Combustion and Flame最新文献

{"title":"An experimental and modeling study on combustion characteristics of dimethyl ether/ nitrous oxide/ chlorine","authors":"Ruining He , Xuan Ren , Xin Bai , Yiheng Tong , Wei Lin , Ziwen Zhao , Frederick Nii Ofei Bruce , Fang Wang , Jinhu Liang , Yang Li","doi":"10.1016/j.combustflame.2025.114071","DOIUrl":"10.1016/j.combustflame.2025.114071","url":null,"abstract":"<div><div>PEG and AP are widely used in strategic and tactical missile engines as key components of composite propellants. It remains a challenge to investigate the detailed combustion mechanism of PEG/AP due to the complex structure and complicated chemical reactions. DME, N<sub>2</sub>O and Cl<sub>2</sub> are the main intermediates of PEG and AP pyrolysis, respectively, which play a crucial role in PEG/AP combustion. DME/N<sub>2</sub>O is also a promising combination propellant because of its high energy content and good combustion and environmental properties. This study systematically investigates the combustion characteristics of DME, N<sub>2</sub>O and Cl<sub>2</sub> mixtures based on experimental measurements. The Ignition Delay Times (IDT) of DME/N<sub>2</sub>O mixtures at equivalence ratios of 0.5, 1.0, and 2.0 (N<sub>2</sub>O as the oxidant) were measured using a high-pressure shock tube at pressures of 10.0 and 20.0 bar and in the temperature range of 1250–1600 K. Besides, half of the N<sub>2</sub>O was replaced by Cl<sub>2</sub> to investigate its impact on the ignition characteristics of DME/N<sub>2</sub>O. The result shows that although the addition of Cl<sub>2</sub> reduces the activity of the fuel mixture system, the ignition activation energy required for ignition has not changed. The laminar flame speeds of DME/N<sub>2</sub>O mixtures were measured by a constant-volume reactor. The equivalence ratios ranged from 0.8 to 1.4, with N<sub>2</sub> content controlled at 60 %, pressure at 1.0 bar, and initial temperature at 298/333 K. The experimental results were simulated using the NUIGMech1.3 model and a constructed model adding Cl<sub>2</sub> related reactions to NUIGMech1.3 in this study. Sensitive and flux analyses were conducted to determine the crucial reactions for the IDT of DME/N<sub>2</sub>O and DME/N<sub>2</sub>O/Cl<sub>2</sub>. The results indicate that the decomposition of DME generates ĊH<sub>3</sub> and ĊH<sub>3</sub>O, which is the most reactivity promoting reaction at all temperatures, and it doesn't be influenced by Cl<sub>2</sub> presence. Meanwhile H-atom abstraction from DME by Ḣ is the most reactivity inhibiting reaction, while it shows promoting effect with the Cl<sub>2</sub> addition, and the H-atom abstraction reaction by O<sub>2</sub>, which did not show significant sensitivity before the addition of Cl<sub>2</sub>, shows the strongest inhibitory effect at this time. H-atom abstraction reactions and C–O bond dissociation are two major pathways of DME primary consumption. Although the presence of Cl<sub>2</sub> did not alter this macroscopic phenomenon, it had a significant impact on the flux of each pathway. Meanwhile, the addition of Cl<sub>2</sub> directly changed the reaction after the third stage in the DME reaction pathways, making the reaction involving Cl<sub>2</sub> dominant at this time. The results in the current study should be a positive contribution to the development and optimization of detaile","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"275 ","pages":"Article 114071"},"PeriodicalIF":5.8,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143529658","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A comprehensive study on dynamics of flames in a nanosecond pulsed discharge. Part II: Plasma-assisted ammonia and methane combustion","authors":"Jinguo Sun,&nbsp;Yupan Bao,&nbsp;Kailun Zhang,&nbsp;Alexander A. Konnov,&nbsp;Mattias Richter,&nbsp;Elias Kristensson,&nbsp;Andreas Ehn","doi":"10.1016/j.combustflame.2025.114076","DOIUrl":"10.1016/j.combustflame.2025.114076","url":null,"abstract":"<div><div>Understanding the flame dynamics in a nanosecond pulsed discharge (NPD) is imperative for the novel technology of plasma-assisted combustion. We conducted a systematic study on the dynamics of atmospheric NPD-assisted flames in single-pulse mode using Rayleigh scattering combined with structured illumination. The study is divided into two parts. Part I detailed the measurements and CH₄/air flame response within the first 500 μs after NPD initiation. In Part II, we extend the study from CH₄ to NH₃, focusing on the dynamics of both CH₄/air and NH₃/air flames across different timescales from nanoseconds to milliseconds. Results show that: (1) within the first 50 ns, the discharge is concentrated in the NH₃/air flame but more diffused and large-volume in the CH₄/air flame; (2) during 1–100 μs, for both flames, a shockwave is formed in the unburnt zone. Meanwhile, a heated gas channel causes a temperature rise in the burnt zone, and particularly, generates a flame kernel in the unburnt zone; (3) when <em>t</em> &gt; 100 μs, plasma-induced turbulence and intense flame movement are observed. Furthermore, the essential differences between NH₃ and CH₄/air flames are revealed in both unburnt and burnt zones. In the unburnt zone, the plasma-induced flame kernel in CH₄/air flames lasts until even 20 ms, whilst for NH₃/air flames, the kernel extinguishes within 500 μs, suggesting a much weaker performance of NPD pulse on NH₃ ignition. In the burnt zone, the temperature rise of the NH₃/air flame is much smaller than that of the CH₄/air flame, indicating a weaker combustion enhancement. These discrepancies cannot be attributed solely to discharge or fuel properties but rather to the plasma-flame coupling. Combining with the discharge morphologies, it is further revealed that the plasma-flame coupling is weaker in NH₃/air flames compared to CH₄/air flames, pronouncing the role of CH radicals in the chemi-ionization process of CH₄/air mixtures. These findings open a promising avenue for advancing plasma-assisted combustion of NH₃ and CH₄.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"275 ","pages":"Article 114076"},"PeriodicalIF":5.8,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143534849","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental and modeling study of 1,2,4-trimethylbenzene pyrolysis at atmospheric pressure in a jet-stirred reactor","authors":"Xiang Gao ,&nbsp;Du Wang ,&nbsp;Qian-Peng Wang ,&nbsp;Cheng-Yin Ye ,&nbsp;Ling-Nan Wu ,&nbsp;Xu-Peng Yu ,&nbsp;Ya-Ning Zhang ,&nbsp;Qing-Bo Zhu ,&nbsp;Zhan-Dong Wang ,&nbsp;Zhen-Yu Tian","doi":"10.1016/j.combustflame.2025.114080","DOIUrl":"10.1016/j.combustflame.2025.114080","url":null,"abstract":"<div><div>The experimental and kinetic modeling results regarding the 1,2,4-trimethylbenzene (T124MBZ) pyrolysis in a jet-stirred reactor coupled with a synchrotron vacuum ultraviolet molecular beam mass spectrometer at the pressure of 1.0 atm and temperatures of 990–1170 K are reported. Seven monocyclic aromatic hydrocarbons, twelve polycyclic aromatic hydrocarbons (PAHs), and five light hydrocarbons were detected and quantified. A comprehensive kinetic model comprising 997 species and 6148 reactions was developed and extensively validated against the experimental data of pyrolysis, high-pressure oxidation, ignition delay times, and laminar burning velocities. The model demonstrates a reasonable ability to replicate these experimental results. ROP analysis indicates that the dominant consumption pathways for T124MBZ involve H-abstraction at methyl sites by H radicals. These H radicals are predominantly generated via H elimination from the methyl groups of <em>o-</em>dimethylbenzyl, yielding methylxylylene, highlighting the significance of isomerization reactions of dimethylbenzyl in T124MBZ pyrolysis. The most significant reactions promoting T124MBZ consumption are H-abstraction at the <em>o</em>-/<em>m</em>-/<em>p</em>-methyl sites of T124MBZ by H radicals and unimolecular decomposition at the C-H bonds of methyl sites of T124MBZ. Unimolecular decomposition of 1,2,3-trimethylbenzene producing 2,3-dimethylbenzyl is the most inhibiting reaction. Indene, indane, naphthalene, phenanthrene, methylphenanthrene, dimethylphenanthrene and pyrene are identified as the major PAHs produced, with <em>o</em>-/<em>m</em>-/<em>p</em>-methylstyrene, particularly <em>o</em>-methylstyrene, serving as key intermediates in PAHs formation.</div></div><div><h3>Novelty and significance statement</h3><div>The novelty of this research lies in its new experimental investigation of T124MBZ pyrolysis. Several intermediates and products formed during T124MBZ pyrolysis were detected and quantified using a synchrotron vacuum ultraviolet molecular beam mass spectrometer. Furthermore, a comprehensive kinetic model for T124MBZ was developed. The agreement observed between the experimental data and the model emphasizes the importance of dimethylbenzyl isomerization reactions in the pyrolysis of T124MBZ. This is significant as it demonstrates that the position of substituents plays a key role in the pyrolysis of aromatic compounds. The findings deepen our understanding of the pyrolysis of polysubstituted benzene derivatives, particularly for T124MBZ, providing valuable insights into the important reaction pathways involved in the pyrolysis of jet fuels, and thus designing more effective regenerative cooling and combustion systems.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"275 ","pages":"Article 114080"},"PeriodicalIF":5.8,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143529657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Publication / Copyright Information","authors":"","doi":"10.1016/S0010-2180(25)00122-1","DOIUrl":"10.1016/S0010-2180(25)00122-1","url":null,"abstract":"","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"274 ","pages":"Article 114084"},"PeriodicalIF":5.8,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143534418","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of cyclopentyl ring-opening β-scission reaction","authors":"Dapeng Liu,&nbsp;Aamir Farooq","doi":"10.1016/j.combustflame.2025.114073","DOIUrl":"10.1016/j.combustflame.2025.114073","url":null,"abstract":"<div><div>The β-scission reaction of the cyclopentyl radical plays a crucial role in cyclopentane oxidation and aromatic formation. However, conflicting reports exist in the literature regarding the primary pathway of this reaction. To reconcile this discrepancy, we conducted time-resolved measurements of allyl radicals generated from the β-scission of cyclopentyl radicals. Experiments were carried out in a shock tube, spanning temperatures of 858 – 1159 K and pressures near 1.4 bar. By analyzing the allyl time-histories, we determined the rate coefficients of the ring-opening C<img>C β-scission of cyclopentyl radical and evaluated the predictive capabilities of literature kinetic models. Our findings unequivocally establish the dominance of the C<img>C cleavage pathway, surpassing the C<img>H β-scission pathway and contributing ∼67 % to the overall reactivity. The literature models use rate values that vary by two orders of magnitude and fail to reproduce our experimental results. Implementation of our determined rate coefficients in the existing literature models gave improved prediction accuracy for intermediate species profiles.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"275 ","pages":"Article 114073"},"PeriodicalIF":5.8,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143519417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Towards hypergolic ignition modeling of monomethylhydrazine and nitrogen dioxide: Ab initio chemical kinetics of CH3NH/CH2NH2/CH2NH and nitrogen dioxide","authors":"Junfeng Bai ,&nbsp;Dan Liu ,&nbsp;Lidong Zhang ,&nbsp;Lei Zhou ,&nbsp;Peng Zhang","doi":"10.1016/j.combustflame.2025.114034","DOIUrl":"10.1016/j.combustflame.2025.114034","url":null,"abstract":"<div><div>The ab initio chemical kinetics of the reactions of CH₃NH/CH₂NH₂/CH₂NH and nitrogen dioxide (NO₂) and its application to modeling hypergolic ignition of monomethylhydrazine (MMH)/NO₂ were investigated in this work. The CCSD(T)/CBS//M062X/6–311G(d,p) single-reference method and the MRCI(9e,8o)/CBS//M062X/6–311++G(d,p) multi-reference method were employed for the kinetically important reaction pathways on the potential energy surfaces (PESs). The temperature- and pressure-dependent rate constants were determined by using the RRKM/Master Equation analysis combined with the transition state theory (TST) and the variable reaction coordinate transition state theory (VRC-TST). The formation of CH₂NH and HONO from CH₂NH₂ and NO₂ dominates in the temperature range of 300–2000K at 0.01 and 1 atm. The calculated rate constants and thermodynamics data were incorporated into a recently established MMH/NO₂ mechanism to investigate their influence on modeling MMH/NO₂ hypergolic ignition. The results show that with the updated rate constants, the consumptions of NO₂ and MMH are promoted, the conversion from CH₂NH₂ to CH₂NH is highly accelerated, and the mole fraction of CH₂NH increases. The rate of production indicates that 28 % of MMH decomposes to CH₃NH and NO₂, 3 % of MMH directly decomposes to CH₂NH and NH₃, and most CH₃NH radicals isomerize to CH₂NH₂ radicals and further form CH₂NH at 1200 K. The sensitivity analyses also substantiate the importance of the decomposition of MMH to CH₃NH/CH₂NH, the isomerization of CH₃NH, the beta-scission of CH₂NH₂, and the reaction of CH₂NH₂+NO₂→CH₂NH+HONO at 1200 K. This work provides not only new kinetic and thermochemical data but also a firm step toward understanding the hypergolic ignition of MMH/NO₂.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"275 ","pages":"Article 114034"},"PeriodicalIF":5.8,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143526922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unexpected indenyl radical formation through thermal decomposition of naphthyl radical at high temperature","authors":"Jun Zhang ,&nbsp;Bingzhi Liu ,&nbsp;Hong Wang ,&nbsp;Jinyang Zhang ,&nbsp;Guangxian Xu ,&nbsp;Jiao Gao ,&nbsp;Yujie Zhao ,&nbsp;Jiwen Guan ,&nbsp;Zhandong Wang","doi":"10.1016/j.combustflame.2025.114097","DOIUrl":"10.1016/j.combustflame.2025.114097","url":null,"abstract":"<div><div>The present study investigated the thermal decomposition of naphthyl radical, a crucial intermediate in combustion processes, through a comprehensive experimental and theoretical investigation. By subjecting 1-naphthyl and 2-naphthyl to temperatures ranging from 730 to 1280 K in a flow reactor, we identified elusive intermediates and isomeric products using synchrotron photoionization mass spectrometry and gas chromatography/mass spectrometry. Noteworthy findings include the unexpected observation of 1-indenyl and indene, alongside crucial intermediates like 1-methylindene and 1-methylene-1<em>H</em>-indene. The mechanistic analysis uncovered prominent features such as isomerization, α-scission, β-scission, and H-addition in the thermal decomposition of naphthyl radicals, with distinct decomposition pathways elucidating the structure-reactivity relationship. By developing a detailed kinetic model based on calculated reaction pathways and rate constants, our simulations align well with experimental observations for the production of naphthalene, 1,2-diethynylbenzene, and phenylacetylene. The deviations between the simulation and experimental results of 1-indenyl and indene underscore the need for further refinement and development of its reaction mechanism and kinetic data.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"275 ","pages":"Article 114097"},"PeriodicalIF":5.8,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143526921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical investigation on the detonative tangential combustion instability in a rocket combustor","authors":"Bu-Kyeng Sung ,&nbsp;Jiro Kasahara ,&nbsp;Jeong-Yeol Choi","doi":"10.1016/j.combustflame.2025.114092","DOIUrl":"10.1016/j.combustflame.2025.114092","url":null,"abstract":"<div><div>In this study, Large Eddy Simulation (LES) is employed to investigate the self-excited detonative tangential combustion instability in a laboratory-scale rocket combustor with multiple impinging-type injectors. Auto-ignition was initiated with an initial condition of 2000 K in the combustor. It was found that the pressure fluctuations generated by ignition did not dissipate, instead, a pair of rotating waves in CW and CCW direction are steepened, promoting the interaction between the pressure wave-heat release rate. The interaction between these pressure waves and the heat release further developed the rotational motion of the heat release zone. This rotational motion coupled with the rotating pressure waves, ultimately establishing a dominant rotating direction. The coupled rotating wave and heat release eventually lead to resonant behavior, resulting in the development of detonative tangential mode instability. During limit cycle operation, the observation of a detonation cell structure further confirmed that tangential mode combustion instability can evolve into a rotating detonation. Comparing this evolution process with the deflagration-to-detonation transition (DDT), it was found to closely resemble the DDT process.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"275 ","pages":"Article 114092"},"PeriodicalIF":5.8,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143519520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Flame transfer function measurements in an annular combustor: Comparison with single flame response under hydrogen enrichment","authors":"Abhijat Verma,&nbsp;Nicholas A. Worth","doi":"10.1016/j.combustflame.2025.114051","DOIUrl":"10.1016/j.combustflame.2025.114051","url":null,"abstract":"<div><div>The full heat-release-rate (HRR) field was imaged in an annular combustor to assess the flame response at each injector simultaneously. The combustor geometry was modified to remove optical occlusions from the imaging setup. It was demonstrated that even very minor optical occlusions could lead to significant differences in the measured flame HRR response. When subject to carefully forced azimuthal modes, the sector-integrated HRR response could be decomposed into azimuthal clockwise and anticlockwise components. When decomposed, the HRR response amplitude was shown to be nearly independent of the azimuthal mode direction in the studied configuration. A comparison was made between the response of the same flame in annular and single flame confinement. For some operating conditions, the sector-wise annular flame transfer functions (FTFs) were found to deviate significantly in amplitude from those for a corresponding single flame combustor. This was attributed to inter-flame interactions and differences in confinement. These effects were modulated by studying flames with different hydrogen content and thus different laminar flame speeds. The flames became more compact with increasing hydrogen content, leading to reduced inter-flame and confinement effects. This lead to more similar FTFs in both amplitude and phase, with the phase for shorter flames being partially explained by a convective time delay based on the bulk velocity and flame height. Under azimuthal forcing, preferences to azimuthal mode direction were not significant and were largely unaffected by inter-flame interactions or confinement effects. However, with increasing hydrogen content, there was a larger variability in the thermoacoustic response between different nominally identical injectors, suggesting a sensitivity to small details in the flow.</div><div><strong>Novelty statement</strong></div><div>The symmetry of the azimuthal thermoacoustic response in an annular combustor was assessed in a full view of the annulus, compared to the blocked view from previous studies. It was shown that even a slight blocking of the view leads to a substantially different measurement. The full view revealed that the acoustic wave direction does not affect the flame transfer function (FTF) as much as what was reported in the past, meaning that parameters in models based on direction-dependent FTFs potentially need adjustment. For the first time, the FTF response was compared in an annular combustor and corresponding single flame under a wide range of carefully forced azimuthal modes, and for a wide variety of flame shapes. Though past studies found differences between the annular and single flame combustors, it was shown here that these differences are reduced when inter-flame and confinement interactions are reduced via hydrogen enrichment.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"275 ","pages":"Article 114051"},"PeriodicalIF":5.8,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143519427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical simulation of transcritical multiphase combustion using real-fluid thermochemical and transport properties","authors":"Mohamad Fathi,&nbsp;Dirk Roekaerts,&nbsp;Stefan Hickel","doi":"10.1016/j.combustflame.2025.114055","DOIUrl":"10.1016/j.combustflame.2025.114055","url":null,"abstract":"<div><div>We scrutinize high-fidelity physical and numerical models for mixing and combustion in high-pressure thermal propulsion systems, where the operating pressure is typically above the critical pressures of the pure fuel and oxidizer, but lower than the cricondenbar values of the mixture. At such transcritical operating conditions, the fluid’s state and transport properties strongly deviate from ideal-gas or ideal-liquid models. The possible coexistence of vapor and liquid phases, governed by the local composition of the fluid mixture, further complicates the physical and numerical modeling. To this end, we present a comprehensive framework for the simulation of combustion at transcritical pressures using multiphase thermodynamics. The Navier–Stokes equations are solved for a multi-component working fluid with thermodynamic properties computed by solving suitable volumetric and caloric state equations combined with phase-splitting equations. The transport properties of the working fluid are modeled using high-pressure correction methods with appropriate structural mixing rules in the co-existence regime. Real-fluid effects on the diffusion driving force are quantified via the thermodynamic correction factor with a proposed extension to the multiphase transcritical regime. The finite-rate chemistry model includes real-fluid high-pressure effects in reaction source terms via the fugacity of the species. Computational results demonstrate the need for accurate models of thermochemical and transport properties and their impact on the predicted ignition behavior of transcritical flames.</div><div><strong>Novelty and Significance statement:</strong> This paper tackles the complexities of simulating transcritical multiphase combustion, highlighting the non-ideal behavior of fluid mixtures under high pressure and the potential coexistence of vapor and liquid phases dictated by local composition. Its significance extends beyond the pure usage of multiphase thermodynamics (MT), which couples the equation of state with vapor–liquid equilibrium calculations to accurately predict the thermodynamic properties of the mixture within the two-phase region. This work generalizes and extends the MT approach to transport properties and the diffusion driving force for real-fluid mixtures at transcritical pressures. Additionally, it introduces a finite-rate chemistry model that comprehensively addresses the real-fluid effects in high-pressure combustion based on species fugacity. The integration of these innovations provides a predictive model of unprecedented accuracy.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"275 ","pages":"Article 114055"},"PeriodicalIF":5.8,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143519426","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}