Proceedings of the Combustion Institute最新文献

{"title":"The effect on soot and its gas precursors of doping ethylene with 2,2,4,6,6-pentamethyl-heptane in the nitrogen-fuel stream of a laminar non-premixed Planar Mixing Layer Flame (PMLF)","authors":"Christian P. Bjork ,&nbsp;Mahmoud K. Ashour ,&nbsp;Evangelos K. Stefanidis ,&nbsp;Chiara Saggese ,&nbsp;Scott W. Wagnon ,&nbsp;Francesco Carbone","doi":"10.1016/j.proci.2025.105787","DOIUrl":"10.1016/j.proci.2025.105787","url":null,"abstract":"<div><div>Synthetic Aviation Turbine Fuels (SATFs) are promising for reducing soot emissions from the aviation sector and diversifying Jet Fuel (JF) sources. Accurately predicting the combustion and emissions behavior of SATFs (and other JFs) necessitates robust experimental databases to elucidate the chemistry of long-chain iso-paraffins, which can compose up to two-thirds of SATF blends and whose behavior is considered to be well-represented by that of iso-dodecane isomers. This study characterizes two laminar non-premixed Planar Mixing Layer Flames (PMLFs) with mild soot loads fueled by nitrogen-diluted ethylene, pure and doped with 2,2,4,6,6-pentamethyl-heptane, respectively. The two PMLFs have the same stoichiometric mixture fraction and total hydrocarbon mole fraction in the fuel stream (<em>X_F,F</em>=<em>X_C2H4,F</em>+<em>X_C12H26,F</em> = 0.260), resulting in nearly the same maximum temperature (<em>T_max</em>≈1800 K) and simple identification of the effects of doping. Importantly, any horizontal PMLF cross-section has a self-similar structure that can be modeled as an equivalent One-Dimensional Counterflow Flame (1D-CF) with vanishingly small strain rate (<em>a</em>). The cross-section at a Height Above the Burner (HAB) of 50 mm is characterized in terms of C₀-C₁₈ gas species using capillary sampling followed by GC-MS analyses. Laser-Induced Emission Spectroscopy (LIES) quantifies the soot volume fraction (<em>f_v</em>) profiles at HAB=25 and 50 mm where Elastic Laser Light Scattering (E-LLS) is performed to determine the <em>a</em> of the equivalent 1D-CFs and the profile of the E-LLS equivalent diameter (<em>d_6,3</em>) of soot. The substitution of 1500 ppm of ethylene with 2,2,4,6,6-pentamethyl-heptane causes an increase of ≈1.5 in the concentrations of several polycyclic aromatic hydrocarbons and <em>f_v</em>. Concurrently, the measured <em>d_6,</em>₃ doubles in the oxidizer stream, yet remains the same in the fuel stream, at HAB=50 mm. Instead, at HAB= 25 mm, the iso-dodecane doping does not affect the <em>d_6,</em>₃ profile in either stream. The experimental results partially validate the chemical reactions and soot formation kinetic model developed at Lawrence Livermore National Laboratory and provide directions to further improve its predictions.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105787"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144841803","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":"Acetaldehyde reactivity at engine-relevant conditions: An experimental and kinetic modeling study","authors":"Jesus Caravaca-Vilchez,&nbsp;Malte Döntgen,&nbsp;Karl Alexander Heufer","doi":"10.1016/j.proci.2025.105828","DOIUrl":"10.1016/j.proci.2025.105828","url":null,"abstract":"<div><div>Understanding the combustion chemistry of acetaldehyde, a carcinogenic by-product formed during the low-temperature oxidation of various hydrocarbons, is essential for reducing harmful emissions in engines. Previous acetaldehyde experimental works have largely focused on low-pressure conditions, with a few exceptions. Some studies report a clear negative temperature coefficient (NTC) behavior for acetaldehyde and highlight the need for further low-temperature, high-pressure experiments to fully characterize it. In this context, acetaldehyde ignition delay times were measured using a rapid compression machine and a shock tube over a wide range of conditions (580–1410 K, 10–40 bar, and equivalence ratios of 0.5–1.5), significantly extending the very limited IDT data available in the literature at 10 bar. At low temperatures, the most comprehensive kinetic models of acetaldehyde greatly underestimate its reactivity, even those that show reasonable performance for flow reactor species measurements from the literature in the same temperature regime. At high temperatures, model predictions were generally in better agreement with the measured data. To improve prediction accuracy, refinements were made within GalwayMech1.0 model, incorporating recently calculated thermochemistry from the literature and modified reaction rate parameters based on direct analogies and literature information. The resulting chemistry revealed that the acetyl peroxy radical is the primary driver of low-temperature reactivity at high pressures through a closed-loop fuel consumption pathway. Further adjustments in the peroxyl radicals chemistry, which is less relevant under low-pressure conditions, successfully separate first-stage and main ignition in the NTC region. At high temperatures, revised H-atom abstraction by <span><math><mover><mrow><mi>H</mi></mrow><mrow><mo>̇</mo></mrow></mover></math></span> and O<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> rates improved high-temperature predictions. Overall, the proposed model outperforms existing mechanisms over a wide range of conditions, but retains uncertainties in the formation of a few minor intermediates. This work highlights the importance of using high-pressure validation targets for comprehensive kinetic modeling and provides a solid foundation for future studies on acetaldehyde oxidation.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105828"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145104440","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":"Dynamic behaviors of flame and molten insulation in electrical wire fire under applied electric field","authors":"Jeong Park ,&nbsp;Chun Sang Yoo ,&nbsp;Suk Ho Chung","doi":"10.1016/j.proci.2025.105862","DOIUrl":"10.1016/j.proci.2025.105862","url":null,"abstract":"<div><div>This study reviews recent findings on the dynamic behaviors of flame and molten insulation material observed in spreading flames over electrical wires under applied electric fields, which is a relevant scenario in electrical wire safety. The important roles of various unique dynamic behaviors in flame spreads are discussed, including fuel-vapor jet ejection from molten polyethylene (PE) surface, internal circulation of molten PE driven by Marangoni convection, dripping of molten PE, electrospray ejecting multiple small droplets from molten PE surface, and lateral dielectrophoresis by migrating a part of main molten PE toward the burnt wire side by forming a secondary molten PE or a liquid film of molten PE and sometimes leading to a formation of splitting flame. Additional behaviors such as vibration/rotation of molten PE due to a vertical dielectrophoresis, flame-leaning toward the burnt wire side caused by ionic wind, and magnetic field induced flame vortices near flame edges are also reviewed. The physical mechanisms of these dynamic behaviors are explained. Various regimes are identified depending on the occurrence of abovementioned phenomena. The dependence of flame spread rate on relevant physical parameters is reviewed, revealing a non-monotonic response to applied AC voltage and frequency, due to the intricate interactions among various dynamic phenomena. Phenomenological correlations are established for the FSR using key physical parameters including wire diameter, wire core diameter, applied voltage and frequency, and radial electric field gradient. To better understand the dynamic behaviors of molten insulation, the combustion of a droplet suspended on a wire was investigated, isolating the effects of solid-to-liquid phase change and the asymmetric distribution of molten PE between the burnt and unburned sides of the wire. The dynamic behaviors of such burning droplets under applied electric fields, along with their underlying mechanisms, are also reviewed and discussed.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105862"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145104448","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":"Novel strategy for combustion enhancement of NH3-air mixture using gliding arc plasma","authors":"B. Aravind ,&nbsp;Ziyu Wang ,&nbsp;Syed Mashruk ,&nbsp;Deanna A. Lacoste ,&nbsp;Agustin Valera-Medina","doi":"10.1016/j.proci.2025.105848","DOIUrl":"10.1016/j.proci.2025.105848","url":null,"abstract":"<div><div>This study investigates the impact of gliding arc plasma (GAP) on the stability and emissions characteristics of a partially premixed ammonia (NH₃)-air swirling flames for wide ranges of global equivalence ratios (ϕ_g). A novel dual-swirl GAP combustor, incorporating conical central electrode serving as a bluff body, is used to generate a rotating gliding arc plasma within the fuel lance. The plasma power is maintained below 1.4 % of the thermal power of the flame across all experimental conditions. This is the first study to apply GAP directly to the fuel side, facilitating premixing immediately after plasma interaction. The results reveal that plasma significantly enhances lean and rich blowout limits by 15–20 % and 30–35 %, respectively. This is mainly due to the continuous local ignition effect through heating and the generation of active species pools. Plasma actuation also results in a substantial reduction in NO and NO₂ emissions, decreasing by 40–80 % and 30–50 %, respectively, depending on ϕ_g in the range of 0.76 to 1.05. Simultaneously, OH* and NH₂* intensities increase by 30–60 % and 70–80 %, respectively. This could indicate an increased NH₂ production favouring NO consumption reactions. A notable NH₃ slip occurs at ϕ_g values exceeding 0.93 and 0.76, indicating incomplete combustion. Numerical results suggest that NO formation predominantly occurs via the HNO pathway, and that plasma conditions promote thermal De-NO_x reactions, notably through NH₂ + NO → NNH + OH and NH₂ + NO → N₂ + H₂O reactions. This study provides critical insights into the potential of GAP technique for advancing NH₃ combustion technologies, offering promising applications for sustainable energy systems.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105848"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145104548","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 evidence for indene formation from o-methylphenyl radical + C2H2/C2H4 reactions","authors":"Zhaohan Chu ,&nbsp;Zhongkai Liu ,&nbsp;Changyang Wang ,&nbsp;Long Zhao ,&nbsp;Bin Yang","doi":"10.1016/j.proci.2025.105859","DOIUrl":"10.1016/j.proci.2025.105859","url":null,"abstract":"<div><div>An experimental study was conducted to investigate the weight growth routes from <em>o</em>-methylphenyl radical (<em>o</em>-CH₃C₆H₄) to indene. <em>o</em>-Nitrosotoluene served as the precursor for <em>o</em>-methylphenyl radicals in this study. Co-pyrolysis of <em>o</em>-methylphenyl radical/C₂H₂ and <em>o</em>-methylphenyl radical/C₂H₄ was investigated utilizing the chemical microreactor and synchrotron vacuum ultraviolet photoionization mass spectrometry. Sampled mass-specific photoionization efficiency (PIE) curves were employed to identify the aromatic species, elucidating interactions between <em>o</em>-methylphenyl radicals and C₂ species. The species detected at <em>m/z</em> = 116 and 118, essential for understanding the reaction mechanism, were identified via matching photoionization cross-sections and adiabatic ionization energies with literature and theoretical values. Specifically, indene and its isomer <em>o</em>-methylphenylacetylene (<em>m/z</em> = 116) were determined in the reaction of <em>o</em>-methylphenyl radical with C₂H₂, while indene and <em>o</em>-methylstyrene (<em>m/z</em> = 118) were identified in the reaction of <em>o</em>-methylphenyl radical with C₂H₄. By combining the identified intermediate species with previous literature basis, the formation pathways for indene, originating from <em>o</em>-methylphenyl radical were discussed in both reaction systems, providing further insights for understanding the indene formation pathways.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105859"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145109371","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":"Constrained reduced-order modeling of reacting flows using bounded Gaussian process likelihoods: application to a furnace operating under MILD conditions","authors":"Muhammad Azam Hafeez ,&nbsp;Alberto Procacci ,&nbsp;Axel Coussement ,&nbsp;Alessandro Parente","doi":"10.1016/j.proci.2025.105846","DOIUrl":"10.1016/j.proci.2025.105846","url":null,"abstract":"<div><div>This study explores the application of a novel constrained reduced-order modeling framework to analyze a furnace operating under Moderate and Intense Low-oxygen Dilution (MILD) combustion conditions. The methodology employs low-cost Singular Value Decomposition (lcSVD) with optimal sensor placement for data compression and reconstruction, followed by Gaussian Process Regression (GPR) with bounded likelihood functions – truncated Gaussian and beta distributions – to ensure physically admissible outputs in high-dimensional combustion simulations. We test these models by predicting the unexplored thermo-chemical states of three-dimensional CH₄/H₂ simulation samples, with varying equivalence ratio, fuel composition (ranging from pure methane to pure hydrogen), and air injector diameter. Results indicate that the beta likelihood constrains species mass fraction predictions to the <span><math><mn>0</mn></math></span>–<span><math><mn>1</mn></math></span> interval by construction, yielding higher accuracy for species with localized distributions. Meanwhile, the truncated Gaussian enhances robustness by respecting realistic thermo-chemical ranges, reducing the influence of outliers, and improving model reliability in sparse or noisy data regions. These models demonstrate computational efficiency and scalability while delivering high-accuracy, physically consistent predictions.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105846"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145216962","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":"Multi-stage interactions on flame stability and NOx emissions in ammonia/methane co-combustion via fuel nitrogen-hydrocarbon separation","authors":"Yuanping Yang ,&nbsp;Tong Si ,&nbsp;Qian Huang ,&nbsp;Peng Ma ,&nbsp;Shuiqing Li","doi":"10.1016/j.proci.2025.105870","DOIUrl":"10.1016/j.proci.2025.105870","url":null,"abstract":"<div><div>Co-combustion of ammonia with fossil fuels is inherently constrained by the trade-off between flame stability and NO<em>_x</em> control. In our prior work, an innovative fuel nitrogen-hydrocarbon separation concept was proposed to broaden the low NO<em>_x</em> emission window by attenuating radical-driven reaction pathways. However, the influence of multi-stage flame interactions and mixing dynamics on the competing routes of nitrogen conversion remains insufficiently understood. In the present study, these effects are systematically investigated using a two-stage tangential swirl burner, with particular emphasis on their roles in governing flame stability and NO<em>_x</em> formation. Experimental investigations reveal three distinct flame stability regimes governed by ammonia blending ratio (<em>E</em>_NH3): (i) dual-flame stable, (ii) detached ammonia flame, and (iii) pulsating methane flame. Increasing <em>E</em>_NH3 enhances primary flame stability, but leads to a higher tendency for pulsation in the secondary methane flame due to attenuated secondary flow. NO<em>_x</em> emissions exhibit a non-monotonic dependence on the primary equivalence ratio (Φ_pri), with an optimal value around 1.05 achieving 134 to 298 ppm (@ 3.5 % O₂) NO<em>_x</em> emissions and NH₃ slip below 10 ppm. Notably, the influence of Φ_pri on NO<em>_x</em> emissions diminishes progressively as the overall equivalence ratio (Φ_ove) increases from 0.6 to 0.9, thereby remarkably broadening the low NO<em>_x</em> emission window. Spatially resolved NH₂* and OH*chemiluminescence analyses demonstrate that NO<em>_x</em> suppression correlates strongly with reduced overlap between primary and secondary reaction zones. Chemical reactor network analysis confirms that reduced multi-stage mixing suppresses HNO formation by impeding oxidative radical entrainment into ammonia-rich zones. This study fills a critical gap by ​quantifying how multi-stage mixing dynamics govern the trade-off between flame stability and NO<em>_x</em> emissions​ in ammonia/methane co-combustion.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105870"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145216959","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":"Combustion and blow-out behavior in a cavity flame holder of Mach 2.5 n-dodecane-fueled scramjet model combustor","authors":"Shinji Nakaya ,&nbsp;Yuki Hirayama ,&nbsp;Yutaro Otsuka ,&nbsp;Kaito Hirose ,&nbsp;Kotaro Nakayama ,&nbsp;Kan Kobayashi ,&nbsp;Masahiro Takahashi ,&nbsp;Sadatake Tomioka ,&nbsp;Mitsuhiro Tsue","doi":"10.1016/j.proci.2025.105834","DOIUrl":"10.1016/j.proci.2025.105834","url":null,"abstract":"<div><div>The supersonic combustion mechanism was experimentally investigated using a Mach 2.5 n-dodecane fueled ramjet/scramjet dual-mode combustor with a cavity flame holder at stagnation pressure of 1021 kPa and a stagnation temperature of 1847 K. Heated n-dodecane was injected from the cavity closeout ramp. Optical diagnostics, including CH* and OH* chemiluminescence and Laser induced breakdown spectroscopy (LIBS), were employed. During steady combustion, the cavity shear-layer stabilized combustion was established autonomously without any assistance of the torch igniter. The local equivalence ratio was measured by moving the breakdown points using a 3-axis high precision motorized stage with measurements of CH* chemiluminescence in the cavity flame holders. Additionally, measurements were performed at fixed positions at 30 Hz as the fuel injection rate increased gradually. The results indicated the intensive OH* chemiluminescence emissions near the lower wall near the closeout ramp during the stable cavity shear-layer combustion. The equivalence ratio in the lower region of the flame was sufficiently rich, exceeding 2, while the flame region with high OH* and CH* signals was stoichiometric or lean. A steep gradient in the equivalence ratio was observed across the flame. During the transient combustion, as the fuel injection rate increased gradually, the equivalence ratio within the cavity increased. Additionally, the equivalence ratio within the cavity was high on the step side and decreases toward the ramp side. Near the flame regions exhibiting strong CH* chemiluminescence signals, the equivalence ratio approached unity. When the flame left the measurement point, the equivalence ratio exceeded 2, showing a substantial gradient across the flame. The flame tip was located near the fuel rich region exceeding 2. The findings of this study provide valuable insights for the design of kerosene-fueled scramjet combustors. Furthermore, the steady cavity flame demonstrated here has potential applications as a piloted flame for staged combustions.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105834"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145216305","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":"Local Rayleigh index reconstruction: Application to plasma-assisted sequential combustion under varying pulse repetition frequency","authors":"Matteo Impagnatiello,&nbsp;Nicolas Noiray","doi":"10.1016/j.proci.2025.105882","DOIUrl":"10.1016/j.proci.2025.105882","url":null,"abstract":"<div><div>This study investigates the influence of Nanosecond Repetitively Pulsed Discharges (NRPDs) on the acoustic response of the second stage of a Constant Pressure Sequential Combustor (CPSC) operating at atmospheric pressure. NRPDs are applied upstream of the second-stage combustion chamber to modify the autoignition process, thereby altering the combustor’s acoustic scattering properties. Large Eddy Simulations (LES) combined with System Identification (SI) methods are employed to better understand the NRPD-flame-acoustic interactions in the sequential flame across three different Plasma Repetition Frequencies (PRF), namely 20, 40, and 60 kHz. Results show that, while NRPDs always improve the overall acoustic scattering properties of the system compared to the combustion without NRPDs, the improvement is non-monotonic with respect to PRF. The most favorable acoustic characteristics are observed at <span><math><mrow><mtext>PRF</mtext><mo>=</mo><mtext>20</mtext></mrow></math></span> kHz. Analysis of local Rayleigh index fields, reconstructed from broadband-forced simulation data, reveals that variations in PRF alter the physical mechanism by which plasma discharges influence system acoustics. Plasma-generated kernels can either directly induce heat release rate fluctuations and act as acoustic energy sources or sinks, or indirectly affect the system’s acoustics by interacting with the main flame brush and modifying its response. The ability to influence the interaction between autoignition kernels and acoustics by simply adjusting the PRF underscores the potential of NRPDs as a versatile tool for controlling the acoustic behavior of sequential combustors, enabling adaptation to the varying operational needs of real gas turbines.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105882"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145216306","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":"Monitoring carbonaceous species in the transition from molecules to particles in shock-tube pyrolysis of toluene by laser induced emission spectroscopy","authors":"Can Shao ,&nbsp;Meysam Khademorezaeian ,&nbsp;Jürgen Herzler ,&nbsp;Greg J. Smallwood ,&nbsp;Thomas Dreier ,&nbsp;Torsten Endres ,&nbsp;Mustapha Fikri ,&nbsp;Christof Schulz","doi":"10.1016/j.proci.2025.105867","DOIUrl":"10.1016/j.proci.2025.105867","url":null,"abstract":"<div><div>Particle inception remains the most enigmatic stage of the formation process of carbonaceous particles. Detailed knowledge of the evolution of optical properties during the transition from molecular species to particles is essential for unraveling this phenomenon and enabling accurate particle volume fraction measurements of freshly formed particles in combustion environments. This study monitors the transition from molecular precursors to incipient soot particles during toluene pyrolysis behind reflected shock waves by laser-induced emission spectroscopy. Time-resolved and spectrally-resolved measurements of laser-induced emission were performed with excitation at 266, 355, 532, or 1064 nm. Microsecond time resolution was provided upon laser-pulse excitation via simultaneous measurements at various spatial locations behind the reflected shock wave, using the reaction-time-resolved detection concept. These measurements trace the evolution of different stages of the carbonaceous species evolving from red-shifted laser-induced fluorescence (LIF) progressing from toluene decomposition and polycyclic aromatic hydrocarbon (PAH) formation to the onset of incipient soot and subsequent laser-induced incandescence (LII) from refractory soot. LII signals recorded after 1064-nm excitation were utilized to identify initial particle formation, while time-resolved LII measurements provided insight into particle-size evolution. These findings contribute to a deeper understanding of soot inception and provide optical properties of the early stage of soot particles.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105867"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145216398","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}