Proceedings of the Combustion Institute最新文献

{"title":"Effect of simultaneous H2 and NH3 addition on soot formation in co-flow diffusion CH4 flame","authors":"Yu Yang, Shu Zheng, Mingxin Xu, Bing Liu, Shaohua Zhu, Ran Sui, Qiang Lu","doi":"10.1016/j.proci.2024.105676","DOIUrl":"https://doi.org/10.1016/j.proci.2024.105676","url":null,"abstract":"Simultaneous blending of hydrogen (H) and ammonia (NH) to hydrocarbon fuels can tackle the safety issues of H and improve burning efficiency of NH. While this strategy brings challenges for soot prediction due to the promotion effect of H and the suppression effect of NH, and the interactions between H and NH. In this study, the simultaneous addition of NH and H on soot formation was experimentally and numerically investigated in a co-flow diffusion CH flame. The interactions between NH and H, and how they impacted different soot formation processes were comprehensively revealed using a detailed soot sectional model. The decrease of peak SVF in CH flame caused by NH was 0.013 ppm, about 31.6 % smaller than that in CH/H flame (0.019 ppm), indicating that the inhibitive effect of NH on soot formation was promoted by H. The existence of H promoted the suppression effect of NH on soot nucleation, condensation and HACA processes in the CH flame. Compared with CH/NH flame, the pyrolysis rates of NH, NH and NH in the CH/NH/H flame were higher since more H and OH radicals were generated via H decomposition. This led to a larger consumption rate of H and OH radicals, which decreased the reaction rates of CH+OH=CH+HO and CH+OH=CH+HO, and promoted the combination of NO and CH. Both factors accounted for a stronger suppression effect of NH on the formation of A1 in CH/H flame than that in CH flame, and thus a stronger inhibitive effect on soot inception and condensation. Compared with the CH flame, NH resulted in a larger decline of H and OH radicals mole fractions in the CH/H flame, which explained the stronger suppression effect of NH on the HACA surface growth process in the CH/H flame.","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"51 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141886424","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":"Light absorption dynamics of brown carbon particles during wood combustion and pyrolysis","authors":"Constantinos Moularas, Philip Demokritou, Georgios A. Kelesidis","doi":"10.1016/j.proci.2024.105513","DOIUrl":"https://doi.org/10.1016/j.proci.2024.105513","url":null,"abstract":"The light absorption dynamics of brown carbon (BrC) particles emitted during combustion or pyrolysis of pinewood are elucidated here using an integrated thermal incineration platform which enables pyrolysis of wood at controlled conditions. This platform is coupled with a variety of real-time aerosol instrumentation and time-integrated sampling systems. The BrC particles emitted from pinewood combustion contain about 80 % of condensed volatile organic compounds (VOCs), regardless of the O concentration, [O]. Removing the condensed VOCs by thermal denuding reveals that BrC nanoparticles from wood pyrolysis ([O] = 0 vol%) have a bi-modal size distribution containing 95 % of nanoscale particles with a mean mobility diameter, = 37 nm and 5 % of large particles with mean = 107 nm. Increasing [O] from 0 to 20 vol%, increases the fraction of large BrC nanoparticles up to 29 % and decreases their mean to 78 nm. In this regard, the average mass absorption cross-section, , of BrC increases from 0.1 to 0.27 m/g with increasing [O]. This indicates that the light absorption of BrC from wood combustion and pyrolysis is determined by the fraction of large particles with mean = 78–107 nm. The BrC measured here can be interfaced with global climate models to estimate the contribution of particulate emissions from biomass combustors and wildfires to global warming.","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"75 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141886427","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":"Modeling reversible soot nucleation with a reduced kinetic mechanism including coronene","authors":"Michael Geuking, Pavan Prakash Duvvuri, Agnes Jocher","doi":"10.1016/j.proci.2024.105636","DOIUrl":"https://doi.org/10.1016/j.proci.2024.105636","url":null,"abstract":"Reversible dimerization of coronene is implemented into a hybrid method of moment based soot model and used with a newly generated reduced mechanism for ethylene combustion. The employed semi-automated mechanism reduction approach includes a novel error function using curve matching of species mole fraction, temperature, and heat release profiles of a counterflow diffusion flame, which was added to a path flux analysis with subsequent sensitivity analysis. The generated reduced mechanism, which maintains predictability of selected higher aromatics, while drastically reducing required computational resources, was validated for species concentration of lower hydrocarbons and aromatics for laminar premixed and counterflow diffusion ethylene flames. It was then used to model reversible dimerization of coronene and to predict soot volume fraction for several laminar premixed flames. For the analyzed cases, the combination of the newly reduced mechanism with the enhanced soot model, including reversible dimerization, was able to enhance the prediction of soot concentration trends. Finally, a discussion on uncertainties related to the equilibrium constant for dimerization is presented.","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"82 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141886429","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":"An integrated framework for accelerating reactive flow simulation using GPU and machine learning models","authors":"Runze Mao, Min Zhang, Yingrui Wang, Han Li, Jiayang Xu, Xinyu Dong, Yan Zhang, Zhi X. Chen","doi":"10.1016/j.proci.2024.105512","DOIUrl":"https://doi.org/10.1016/j.proci.2024.105512","url":null,"abstract":"Recent progress in machine learning (ML) and high-performance computing (HPC) have brought potentially game-changing opportunities in accelerating reactive flow simulations. In this study, we introduce an open-source computational fluid dynamics (CFD) framework that integrates the strengths of ML and graphics processing unit (GPU) to demonstrate their combined capability. Within this framework, all computational operations are solely executed on GPU, including ML-accelerated chemistry integration, fully-implicit solving of fluid transport PDEs, and computation of thermal and transport properties, thereby eliminating the CPU–GPU memory copy overhead. Optimisations both within the kernel functions and during the kernel launch process are conducted to enhance computational performance. Strategies such as static data reorganisation and dynamic data allocation are adopted to reduce the GPU memory footprint. The computational performance is evaluated in two turbulent flame benchmarks using quasi-DNS and LES modelling, respectively. Remarkably, while maintaining a similar level of accuracy to the conventional CPU/implicit ODE-based solver, the GPU/ML-accelerated approach shows an overall speedup of over two orders of magnitude for both cases. This result highlights that high-fidelity turbulent combustion simulation with finite-rate chemistry that requires normally hundreds of CPUs can now be performed on portable devices such as laptops with a medium-end GPU.","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"31 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141886428","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":"Analysis of spontaneous ignition of hydrogen-enriched methane in a rectangular tube","authors":"Shangyong Zhou, Jianjun Xiao, Zhenmin Luo, Mike Kuznetsov, Zheng Chen, Thomas Jordan, Daniel T. Banuti","doi":"10.1016/j.proci.2024.105681","DOIUrl":"https://doi.org/10.1016/j.proci.2024.105681","url":null,"abstract":"This study investigates the spontaneous ignition of high-pressure hydrogen-enriched methane in air within a rectangular tube. A computationally efficient approach has been adopted, utilizing a reduced reaction mechanism and ignition delay model within a 3D Large Eddy Simulation (LES) framework. This approach overcomes the limitations of traditional 1D and 2D simulations with detailed chemistry models, which are unable to accurately reproduce the complex 3D shock wave structures within the tube. The simulated shock wave behavior during 9 MPa hydrogen leakage (case 1) and 11 MPa 90 vol% hydrogen/10 vol% methane mixture leakage (case 2) are found to agree well with experimental observations. In case 2, the hot spots generated by reflected shock waves and Mach reflections ignite the hydrogen/methane-air mixture, resulting in three sequential spontaneous ignitions. The flame is observed to primarily propagate along the tube corners and wall centers, with the central ignition spreading across the entire cross-section. For the 25 MPa 24 vol% hydrogen/76 vol% methane mixture leakage (case 6), the shock intensity is significantly reduced due to the increased methane proportion, leading to spontaneous ignition only at the tube corners when the hemispherical shock wave reflects from the wall. The flame predominantly forms downstream along the tube corner, gradually spreading along the tube wall. It is indicated that while the probability of spontaneous ignition decreases with increasing methane content, the risk remains significant under sufficiently high pressures. To the best our knowledge, this study represents the first 3D large eddy simulation of spontaneous ignition for high-pressure hydrogen-enriched methane leakage into air, providing valuable insights into the underlying physical phenomena.","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"71 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141886425","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 simulations of TiO[formula omitted] production in a laminar coflow H[formula omitted]/Ar/TTIP diffusion flame: Comparison with experiments and parametric sensitivity study","authors":"B. Franzelli, J. Bonnety, J. Yi, Y. Ogata, A. Cuoci, C. Betrancourt","doi":"10.1016/j.proci.2024.105599","DOIUrl":"https://doi.org/10.1016/j.proci.2024.105599","url":null,"abstract":"Metal-oxide nanoparticles are paving the way for the development of new materials, and flame spray pyrolysis (FSP) systems are gaining attention for their large-scale production. On an industrial level, precise control of particle characteristics is needed while guaranteeing an almost zero-emission process. In this context, computational fluid dynamic (CFD) simulations of nanoparticle production in flames are sought to optimize the design of FSP systems. In this work, numerical simulations of TiO nanoparticles production from Titanium(IV) isopropoxide (TTIP) are performed for a laminar coflow H/Ar flame as a first step towards this objective. To lower the CPU cost for 2-D simulations, reduced descriptions for the gas phase and for nanoparticles are considered. For H combustion, a 10-species kinetic mechanism is retained. Five different submechanisms are tested for the description of TTIP conversion into Ti(OH), considered as the TiO precursor. The description of the solid phase relies on a classical three-equation monodisperse formulation. The objective of this work is not to validate the considered CFD strategy, for which a more extensive database would be required, but to identify the most relevant processes for flame synthesis in a diffusion flame by performing a parametric sensitivity study. The originality of this investigation relies on the study of particle characteristics along an H laminar flame in a non-premixed configuration. Thus, the focus of the parametric study is on the effect on nanoparticle characteristics of: (1) diffusion processes of gaseous phase and nanoparticles; (2) aerosol processes. Numerical results are compared to experimental data in terms of conversion rate, volume fraction, and primary particle diameter along the flame height. Trends from the literature on the effect of aerosol process parameters are retrieved. Results highlight the key role of diffusion processes on nanoparticle production in non-premixed flames and the need for future improvements of TTIP conversion kinetics.","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"78 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141886434","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":"Soot formation as a function of flow, flame and mixing field above evaporating fuel films in an optically accessible engine","authors":"Marius Schmidt, Jannick Erhard, Lars Illmann, Cooper Welch, Andreas Dreizler, Benjamin Böhm","doi":"10.1016/j.proci.2024.105605","DOIUrl":"https://doi.org/10.1016/j.proci.2024.105605","url":null,"abstract":"Liquid fuel wall films are a known source of hydrocarbon and soot emissions in direct-injection spark-ignition (DISI) engines. Therefore, a comprehensive understanding of the evaporation, mixing, and combustion processes above wall films is desirable. In this study, laser-induced fluorescence (LIF) of acetone excited at 315nm is used to measure the fuel mole fraction in the gas phase above a wall film in an optically accessible DISI engine. To this end, acetone and 3-pentanone are characterized at excitation wavelengths from 305 to 316nm in a heated jet experiment under atmospheric conditions. It is shown that the excitation of acetone at 315nm results in a signal that is sufficiently temperature-independent under engine-relevant conditions. In addition, simultaneous high-speed particle image velocimetry (PIV) and Mie-scattering capture the flow field and cross-sectional flame development. The formation of soot is characterized by natural luminosity. A late injection of acetone during the compression stroke from a single-hole Spray M injector is used to add approximately 8% of the fuel to the homogeneously premixed isooctane-air mixture and form a fuel film on the piston surface. Heavy soot formation occurs when the engine is operated under cold start conditions. After combustion, incandescent soot structures form and persist until the exhaust phase. These soot structures are attributed to the pyrolysis of the fuel as it evaporates into the oxygen-depleted, high-temperature burnt gas. Increasing wall temperatures during cold-start cycles significantly reduces soot formation. However, even at similar temperature levels, strong variations occur. A multi-parameter analysis revealed a strong correlation of the projected soot area with the flow field at ignition and the acetone mole fraction above the film. It is shown that delayed flame-film contact reduces soot formation since it increases the time for evaporation and promotes mixing of acetone-rich regions. Acetone mole fractions in the bulk flow indicate strong turbulent mixing, with fuel-rich regions contributing to soot formation during combustion being typically limited to within 3 mm of the wall.","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"100 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141886431","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 stabilisation in a highly-lifted premixed jet flame in a hot cross flow","authors":"Harikrishna Tummalapalli, Evatt R. Hawkes, Bruno Savard, Ji-Woong Park, Tianfeng Lu","doi":"10.1016/j.proci.2024.105452","DOIUrl":"https://doi.org/10.1016/j.proci.2024.105452","url":null,"abstract":"We report a large-scale direct numerical simulation (DNS) of a highly-lifted premixed methane–air jet flame in a hot cross flow, relevant to axially staged gas-turbine combustion systems. The jet Reynolds number is 17,938 and the cross flow Reynolds number is 28,822. Apart from pressure, the thermochemical parameters closely match practical axially staged combustors. A premixed methane–air jet with an equivalence ratio of 0.7 is injected into a vitiated cross flow comprising combustion products from a methane–air mixture at an equivalence ratio of 0.5 and atmospheric pressure. The DNS is analysed to understand the stabilisation mechanism of the flame. The DNS reveals a lifted flame quasi-statically anchored on the leeward side. Time scale and OH budget analyses demonstrate that autoignition is the dominant stabilisation mechanism, and the leeward side anchoring is explained with reference to residence time and scalar dissipation rate. The study also shows that the interaction between the counter-rotating vortex pair and leeward ignition kernels results in a premixed flame in the jet core.","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"55 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141886433","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":"Non-conforming Schwarz-spectral element method for low Mach number reacting flows","authors":"Ioannis Kavroulakis, Dimitris Papageorgiou, Christos E. Frouzakis, Paul Fischer, Ananias Tomboulides","doi":"10.1016/j.proci.2024.105506","DOIUrl":"https://doi.org/10.1016/j.proci.2024.105506","url":null,"abstract":"Overlapping-domain methods together with current exascale computing capabilities can provide significant speedup to large-scale direct numerical simulations (DNS). The objective of this work is to examine the accuracy and performance of the non-conforming Schwarz method for the simulation of low Mach number reacting flows using the spectral element solver Nek5000. The overlapping-domain approach already implemented in Nek5000 for incompressible non-reacting scenarios is extended to reacting flows in open domains. First, the spatial and temporal convergence properties of the method were tested using the analytical solution for a 1-D reacting transient model problem developed for this purpose. The results show that the method preserves the exponential convergence in space with respect to polynomial order and exhibits a third-order accuracy in time, when the flame front is located away from the interdomain boundaries.When the flame approaches the interdomain boundaries, a first-order accuracy in time is observed, similar to non-reacting flows in overlapping domains when no sub-iterations are performed. Additionally, a simulation of a propagating turbulent lean premixed H-air flame in a 2-D circular domain was conducted, demonstrating that with adequate resolution in both overlapping domains, the flame transitions smoothly from the inner to the outer domain. Subsequently, a DNS of a 3-D early flame kernel development (EFKD) in decaying homogeneous isotropic turbulence (HIT) was carried out to assess accuracy and performance of the method under turbulent conditions, closely resembling scenarios during the initial phase of internal combustion engines (ICEs). Temperature and species profiles, flame consumption speed, as well as other quantities of interest, were found to be in very good agreement with single-domain results, showing that the method retains its accuracy. Finally, a strong scaling study of the EFKD configuration reveals that the parallel performance and speedup show the expected behavior of the overlapping-domain method for low Mach number reacting flows.","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"366 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141886435","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":"Experimental and numerical study of pollutant emissions from a domestic condensing boiler fed with natural gas enriched with H[formula omitted]","authors":"A. Cuoci, G. Bucci, M. Sutti, T. Faravelli, A. Frassoldati","doi":"10.1016/j.proci.2024.105473","DOIUrl":"https://doi.org/10.1016/j.proci.2024.105473","url":null,"abstract":"Hydrogen is recognized as a promising resource for decarbonizing not only the industrial sector, but also the domestic heating systems. Through the partial substitution of natural gas with hydrogen, domestic combustion-based conversion systems can potentially offer improved efficiency, reduced carbon emissions, and cleaner combustion, i.e., lower levels of particulate matter. However, hydrogen exhibits properties that are significantly different from natural gas: (i) because of its higher laminar flame speed, hydrogen is more susceptible to flashback, which may pose significant concerns from the safety point of view; (ii) because of its higher adiabatic temperature, NOx emissions are expected to increase. Thus, experimental and numerical investigations are needed to better understand how the addition of hydrogen to the fuel mixture modifies the combustion process and how to mitigate/control the higher propensity to flashback and NOx formation within domestic devices.","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"5 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141886436","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}