Proceedings of the Combustion Institute最新文献

{"title":"Exhaust emissions point measurements on the secondary stage of an NH3-RRQL system","authors":"Cristian D. Avila Jimenez ,&nbsp;Renee Cole ,&nbsp;Jamie Parnell ,&nbsp;Mark Peckham ,&nbsp;David Wu ,&nbsp;Benjamin Emerson","doi":"10.1016/j.proci.2025.105791","DOIUrl":"10.1016/j.proci.2025.105791","url":null,"abstract":"<div><div>The Rich-Relaxation-Quench-Lean (RRQL) combustion system was recently proposed to increase combustion efficiency in ammonia (NH₃)-fueled gas turbines while reducing nitrogen oxides (NO_x). Success requires precise control of the lean secondary stage, where air oxidizes the remaining fuel from the rich primary stage. However, understanding pollutants distribution across the secondary stage is crucial for designing RRQL systems that minimize NO_x and nitrous oxide (N₂O) emissions. This study experimentally investigates axial and radial distributions of exhaust species across the secondary stage of a lab-scale NH₃-fueled RRQL burner. The burner operated with rich premixed NH₃–air mixtures and employed a secondary air injection geometry of five-4.1 mm diameter holes, selected for its ability to stabilize diffusion-like flames at <em>ϕ_global</em> = 0.85 and premixed-like flames at <em>ϕ_global</em> = 0.60. A fused quartz probe enabled gas sampling at multiple locations upstream within, and downstream from the secondary injection plane. At <em>ϕ_primary</em> = 1.13, results show that NO is formed slightly upstream the air injection plane, whereas NO₂ is rapidly produced downstream and NH₃ and N₂O slip through the walls between the jets. A notable fraction of total NOₓ was found to be NO₂, post-secondary combustion zone, underscoring the need to consider NO₂ explicitly in overall emissions assessments of staged NH₃ combustion systems. Decreasing <em>ϕ_global</em> to 0.60 reduces the overall emissions, highlighting the importance of premixed-like combustion in pollutants mitigation in the secondary stage. Although similar trends were observed at <em>ϕ_primary</em> = 1.15, higher NO_x levels resulted from increased NH₃ availability. However, thermal insulation of the combustor walls effectively reduced NH₃ slip, likely due to enhanced non-oxidative cracking, enabling sub-10 ppm N₂O emissions. These findings emphasize the importance of simultaneous primary and secondary stage tuning, reduction of heat losses, and the promotion of premixed-like combustion through adequate jet momentum for optimal performance of NH₃-fueled RRQL systems.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105791"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144724632","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":"Kinetic study of ozone-sensitized low- and high-temperature oxidation of dimethyl carbonate","authors":"Bowen Liu,&nbsp;Rui Bo,&nbsp;Hao Zhao","doi":"10.1016/j.proci.2025.105788","DOIUrl":"10.1016/j.proci.2025.105788","url":null,"abstract":"<div><div>The low- and high-temperature oxidation of dimethyl carbonate (DMC), a key electrolyte component in lithium-ion batteries (LIBs), was carried out with ozone (O₃) addition by using an atmospheric pressure Jet Stirred Reactor (JSR) from 400 to 1200 K. Kinetic analysis of DMC oxidation was conducted using the coupled Plug Flow Reactor-Perfectly Stirred Reactor (PFR-PSR) module. Without O₃ addition, the oxidation of DMC initiated at 950 K with no low-temperature reactivity. However, the low-temperature chemistry of DMC was observed from 450 K with O₃ addition, and O₃ significantly enhanced the low-temperature reactivity of DMC. Two kinetic models with incorporating the O₃ sub-model were employed and predicted the experimental data reasonably well, even though slightly overpredicted DMC oxidation above 550 K under the fuel-lean condition. Furthermore, a temperature-independent coefficient (TIC) behavior of DMC with O₃ addition was observed between 600 and 950 K both in experiments and simulations, which was associated with the pyrolysis of DMC radicals to CH₂O and CO₂, and then to CO, while the low-temperature oxidation pathway through 1^st and 2^nd O₂ addition and CO oxidation to CO₂ was negligible. The fast pyrolysis reaction rates of O₃ and DMC radicals, such as CH₃OC(=O)OCH₂ and CH₃OC(=O), explain the TIC behavior in the pathway and sensitivity analyses. This work used O₃ to mimic the oxidizing environment in LIBs by providing active atomic oxygen, and implied that the early degradation of LIBs could be attributed to the low-temperature oxidation of DMC with reactive oxygen species. It provides kinetic evidence for a higher level of CO₂ and a lower level of CO in the initial stage of the thermal runaway in LIBs.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105788"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144780514","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":"Structure and nitrogen oxide emissions of confined turbulent hydrogen jet flames","authors":"T.L. Howarth ,&nbsp;S. Nerzak ,&nbsp;P. Gruhlke ,&nbsp;J.T. Lipkowicz ,&nbsp;L. Panek ,&nbsp;S. Pfadler ,&nbsp;M. Gauding ,&nbsp;H. Pitsch","doi":"10.1016/j.proci.2025.105851","DOIUrl":"10.1016/j.proci.2025.105851","url":null,"abstract":"<div><div>In this work, a database analysis of three-dimensional direct numerical simulations using detailed chemistry is presented considering a turbulent lean premixed hydrogen/air round jet flame at elevated pressure and temperature (<span><math><mrow><mi>ϕ</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>5</mn><mo>,</mo><msub><mrow><mi>T</mi></mrow><mrow><mi>u</mi></mrow></msub><mo>=</mo><mn>530</mn><mtext>K</mtext><mo>,</mo><mi>p</mi><mo>=</mo><mn>8</mn><mi>atm</mi></mrow></math></span>), subject to different levels of domain confinement by solid walls. It is shown that for sufficiently small domain sizes, a coherent recirculation zone is present as expected; however, this does not affect the flame structure, consistent with experiments of attached hydrogen flames. Examination of velocity statistics indicates that, while both turbulent kinetic energy and Reynolds shear stresses increase with increasing domain size, these changes occur sufficiently far away from the flame. Each of the flames experiences the same level of mean shear, leading to the same flame structure. Despite identical turbulence-flame interactions between cases, nitrogen oxide (NO) emissions from the flames are observed to be different. For flames with recirculation zones comparable in size to the flame height, the superadiabatic temperatures caused by intrinsic flame instability are retained within the recirculation zone. Often, residence times in the post-flame are too short for locally elevated temperatures to have a significant impact on thermal NO formation. However, when these higher temperatures are coupled with the long fluid residence time in the recirculation zone, despite lower global residence times, this analysis shows that NO emissions from the flame can be enhanced.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105851"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145104442","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":"Microgravity flame extinction induced by a moving air vortex ring","authors":"Sainan Quan ,&nbsp;Feng Zhu ,&nbsp;Jinglong Lyu ,&nbsp;Caiyi Xiong ,&nbsp;Xinyan Huang ,&nbsp;Shuangfeng Wang","doi":"10.1016/j.proci.2025.105825","DOIUrl":"10.1016/j.proci.2025.105825","url":null,"abstract":"<div><div>With the growth of outer space exploration missions, a safe, effective and clean fire extinguishing in microgravity spacecraft environment is critical. This paper explores the microgravity flame extinction dynamics induced by a moving air vortex ring. Tests were conducted both on the ground and in microgravity by a drop tower for comparison. An electromagnetic piston-tube system was designed to produce well-controlled air vortex ring to extinguish candle flames with different heat release rates (HRRs). We found a linear extinction boundary correlating the flame HRR with the Reynolds number and characteristic thickness of vortex ring. The flame extinguishing efficiency of air vortex ring in microgravity is 30 % higher than that on the ground. To explain the underlying mechanism, the flame stretch rate that accounts for the unsteady effect, i.e., the competition between external disturbance and flame self-stabilization, was examined. The absence of gravity and buoyancy has a minimum effect on the vortex ring but reduces the oxygen supply and flame diffusion, thereby the flame in microgravity is more vulnerable to vortex ring disturbance. The power of generating a vortex ring is 2–3 orders of magnitude lower than the HRR of flame that it can extinguish, and such a power requirement can be further reduced by 20–30 % in microgravity. This work reveals limiting conditions of vortex ring-induced flame extinction in microgravity and helps design future clean firefighting system for space travel.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105825"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145104445","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":"Kinetic coupling effects on the extinction limits of diffusion flames of hydrocarbons blended with ammonia","authors":"Min Kyeong Yoon ,&nbsp;Frederick L. Dryer ,&nbsp;Michael P. Burke ,&nbsp;Sang Hee Won","doi":"10.1016/j.proci.2025.105801","DOIUrl":"10.1016/j.proci.2025.105801","url":null,"abstract":"<div><div>Chemical kinetic coupling effects between NH₃ and liquid hydrocarbon fuels on extinction limits of diffusion flames are experimentally and numerically investigated. Three n-alkanes (n-heptane, n-decane, and n-dodecane), isooctane as a representative fully branched isoalkane, and toluene as a representative mono-aromatic are each tested, along with their blends with NH₃. The measured extinction strain rates are analyzed, employing transport-weighted enthalpy and radical index to demonstrate relative changes of chemical kinetic potentials for each fuel evaluated. The results show a significantly lower chemical kinetic potential for NH₃, compared to hydrocarbon fuels. Comparison of extinction limits as a function of transport-weighted enthalpy multiplied by radical index for fuel/NH₃ mixtures shows potential promotive effects for n-alkanes and no significant coupling for isooctane and toluene. Planar laser-induced fluorescence is applied to quantify OH concentrations for n-heptane, isooctane, and their mixtures with NH₃, and data are modeled to test the fidelity of chemical kinetic model predictions. It is found that including interaction reactions of n-alkyl and isoalkyl fragments with NH₂, and the reactions involving methylamine and cyanide are critical to predicting OH production rates, as well as extinction limits for hydrocarbon/NH₃ blends. Promotive effects of NH₃ blending on n-alkanes diffusion flame extinction limits are primarily from higher flame temperatures due to the reduced fraction of CO₂ found in the flame products. In the case of isooctane blended with NH₃, the formation of two main isoalkyl fragments, CH₃ and C₃H₆, are found to interact with NH₂, resulting in the suppression of the reactive radical pool population and kinetic inhibition. A significantly weaker reactive radical pool in toluene oxidation leads to more significant inhibitive kinetic coupling from NH₃-related reactions.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105801"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144830201","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":"Propagation modes and statistics of near-limit hydrocarbon detonations","authors":"Liliana Berson,&nbsp;Anthony Morales,&nbsp;Rachel Hytovick,&nbsp;Robyn Cideme,&nbsp;Kareem Ahmed","doi":"10.1016/j.proci.2025.105808","DOIUrl":"10.1016/j.proci.2025.105808","url":null,"abstract":"<div><div>Universal propagation mechanisms and structural dynamics of hydrocarbon detonations near the detonation limit are investigated using MHz-rate shadowgraph and CH* chemiluminescence imaging to capture the coupled shock and reaction front. A total of 310 realizations of methane-oxygen and ethylene-oxygen mixtures with varied nitrogen dilution were conducted in a fully automated thin-channel detonation facility. Spatial wavefront velocity fields were extracted from high-speed imagery to compute ensemble statistics, including probability density functions, and the mean, variance, skewness, and kurtosis. The transition from freely propagating detonations to the onset of spin is distinctly separated into four propagation regimes: CJ multiheaded, transitional multiheaded, weak multiheaded, and singleheaded. These regimes are defined by the emergence and eventual dominance of transverse detonation waves, which compensate for weakening cellular instabilities by driving local velocities significantly above the Chapman-Jouguet velocity. This shift in mechanism is shown to be clearly linked to the lack of prompt autoignition by the leading shock indicated by the increasing induction length. The modes are shown to be separable statistically with the combination of the mean velocity and the coefficient of variation (standard deviation scaled by the mean). Transverse detonations are observed to form through the autoignition of large unreacted gas pockets in transverse wave collisions. The induction length is shown to govern the transition, with increasing length correlating to broader velocity distributions (higher variance and skewness) and a shift toward sub-Chapman-Jouguet velocities. Elevated kurtosis values mark the presence of overdriven transverse detonations as statistical outliers. The product of the activation energy and the Von Neumann density ratio, which effectively captures the effects of the activation energy and molecular collisions, were shown to differentiate the modes.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105808"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144830203","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 and precursor chemistry in Counterflow flames of aviation fuel surrogates","authors":"Chiara Saggese ,&nbsp;Russell Whitesides ,&nbsp;Scott W. Wagnon ,&nbsp;Tanusree Chatterjee ,&nbsp;Fabian P. Hagen ,&nbsp;Petros Vlavakis ,&nbsp;Nils Schraud ,&nbsp;Dimosthenis Trimis","doi":"10.1016/j.proci.2025.105816","DOIUrl":"10.1016/j.proci.2025.105816","url":null,"abstract":"<div><div>To meet market demands, the aviation sector is interested in utilizing drop-in Synthetic Aviation Turbine Fuels (SATF), either as neat fuels or in blends with conventional Jet A. SATF currently approved in standard specifications may have lower aromatic content with significant fractions of normal, branched, and cyclo-alkanes. Fundamental studies on soot formation from aviation fuels (Jet A, SATF) and their surrogate components are essential to understand how fuel composition influences soot and soot precursor formation. This study reports new measurements of polycyclic aromatic hydrocarbons (PAH) and soot in counterflow diffusion flames (CDFs) of aviation fuel surrogates. Both intrusive and non-intrusive diagnostics are employed to determine the profiles of temperature, gas phase species, PAHs (up to C16), and soot volume fraction (SVF) in CDFs of iso-octane and surrogate mixtures. These measurements shed light on the transition of soot precursors to primary soot particles. In addition to serving as a common surrogate component in Jet A surrogate mixtures, iso-octane is a template species for larger, less volatile branched alkanes found in SATF mixtures. The newly developed Lawrence Livermore National Laboratory (LLNL) PAH and soot model successfully captures temperature, precursor species, and SVF profiles for the mixtures and conditions discussed in this work. Finally, a high-fidelity surrogate for Jet A is proposed that matches targeted physical and chemical properties well, while leveraging the wide range of candidate fuel molecules available in the LLNL detailed chemical model. The proposed surrogate formulation is validated against newly acquired measurements of the surrogate and literature measurements of Jet A. These new experiments and simulations provide critical insights into the PAH and soot formation from aviation fuels. Reaction pathways which require further investigation are highlighted, such that future work may bridge the remaining quantitative gaps in predicting soot formation from aviation fuel surrogates and surrogate components.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105816"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144860421","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":"Data assimilation of state-indirect observations for constraining detonation wave dynamics","authors":"James J. Hansen ,&nbsp;Davy Brouzet ,&nbsp;Matthias Ihme","doi":"10.1016/j.proci.2025.105812","DOIUrl":"10.1016/j.proci.2025.105812","url":null,"abstract":"<div><div>This study investigates the integration of sparse experimental observations into numerical simulations of detonation waves through data assimilation (DA). We extend a two-step local ensemble transform Kalman filter (LETKF) framework to assimilate numerically generated Schlieren and chemiluminescence images into simulations of a methane–oxygen detonation wave with detailed chemistry. Using an ensemble of 30 simulations, we demonstrate that the method can effectively constrain detonation wave dynamics despite the chaotic and highly nonlinear nature of the complex shock system. Results show that the LETKF reduces errors in unobserved state variables by up to 70%, successfully reconstructing key detonation structures including triple points, Mach stems, and transverse waves. The framework exhibits robustness across multiple assimilation cycles with a 50 kHz observational cadence, maintaining consistent state estimation even as ensemble members naturally diverge. While the method excels at constraining structural features like density and temperature fields, we observe that intermediate species distributions require more frequent observation due to their localized spatial distribution. This work demonstrates the potential of DA techniques for advancing pressure-gain combustion research by enabling the fusion of limited experimental diagnostics with high-fidelity numerical simulations, providing a framework for enhanced understanding of detonation dynamics in practical systems.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105812"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145060349","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 investigation of non-premixed ammonia flames stabilized on a heated slot burner","authors":"Daniel Kretzler ,&nbsp;Rishabh Puri ,&nbsp;Björn Stelzner ,&nbsp;Thorsten Zirwes ,&nbsp;Fabian P. Hagen ,&nbsp;Oliver T. Stein ,&nbsp;Dimosthenis Trimis","doi":"10.1016/j.proci.2025.105854","DOIUrl":"10.1016/j.proci.2025.105854","url":null,"abstract":"<div><div>In this study, non-premixed laminar ammonia/air flames are investigated using a custom-designed heated slot burner developed at KIT. This innovative setup enables investigations into ammonia decomposition and pollutant formation processes through in-situ diagnostics, numerical simulations, and global performance analyses, providing a unique dataset. Experiments are conducted at three oven temperatures (T = 1073 K, 1123 K, and 1173 K) and two thermal loads (0.2 and 0.6 kW) at a global equivalence ratio of <span><math><mrow><mi>Φ</mi><mo>=</mo><mn>1</mn></mrow></math></span>. Inlet temperatures, as well as qualitative insights into NH*, NH₂*, and OH* along the flame are obtained using thermocouples and emission spectroscopy. To assess global combustion characteristics, gas analyzers measure exhaust species, including NO, NO₂, N₂O, NH₃, and O₂. The experimental setup is reconstructed in two dimensions for numerical simulations using an in-house OpenFOAM solver. Flame and emission characteristics are investigated for different operating conditions and chemical mechanisms. While experiments and simulations agree well regarding flame length, flame stability, and chemiluminescence profiles, some deviations in exhaust gas emissions remain. These are attributed to experimental uncertainty from the assumption of flow symmetry, boundary conditions, and uncertainty due to the choice of chemical reaction mechanism at elevated temperatures. Emissions are strongly influenced by oven temperature and flow velocity, with lowest NH₃, N₂O, and NO_x levels observed at high oven temperatures. The non-premixed configuration achieves NO_x emissions down to 335 ppmv at <span><math><mrow><mi>Φ</mi><mo>=</mo><mn>1</mn></mrow></math></span>, significantly below values from premixed combustion, which typically exceed several thousand ppmv. Pathway analysis reveals that the investigated reaction mechanisms predict routes with different relative contributions to NO production, but provide similar trends for NO consumption. The results highlight the suitability of the platform for systematic ammonia combustion studies and the potential of non-premixed strategies for NO_x mitigation.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105854"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145154443","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 of the oblique detonation initiation in ammonia/hydrogen/air mixtures","authors":"Yue Sun ,&nbsp;Siyang Jiao ,&nbsp;Hongbo Guo ,&nbsp;Qiang Li ,&nbsp;Baolu Shi ,&nbsp;Majie Zhao","doi":"10.1016/j.proci.2025.105826","DOIUrl":"10.1016/j.proci.2025.105826","url":null,"abstract":"<div><div>In this paper, two-dimensional numerical simulations of oblique detonation waves at the altitude of 30 km are carried out using Navier-Stokes equations coupled detailed chemical reaction. We investigated the characteristic parameters and the morphology of oblique detonation induction region with different Mach number in ammonia/hydrogen/air mixtures and the effect of the hydrogen percentage on the initiation characteristics. The numerical simulation results show that, in pure ammonia, the transition from oblique shock wave to oblique detonation wave changes from abrupt to smooth type, and the length of induction region decreases by more than a factor of ten, as the Mach number increases from 10 to 12. While, the flow field structure of the oblique detonation wave induction region is more complex due to the presence of compression waves. When <em>Ma</em> = 10, a long induction region is detrimental to the initiation of oblique detonation. Hydrogen addition is a potential solution. As the hydrogen content increases from 0 % to 100 %, the characteristic length of the induction region is significantly reduced. In blended fuels with higher hydrogen content and lower ammonia content, the characteristic length becomes even shorter than that of pure hydrogen fuel. After adding hydrogen, the intensity of the compression waves decreases, and a smooth transition structure is formed. Additionally, the oblique detonation wave in ammonia can achieve higher pressure than that in hydrogen at the same equivalence ratio, and this effect is particularly significant under high Mach numbers. In summary, ammonia is more suitable as a fuel for oblique detonation engines at high Mach numbers, while adding hydrogen at low Mach numbers can improve detonation performance.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105826"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145004324","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}