Combustion and Flame最新文献

{"title":"Probing the combustion characteristics of micron-sized aluminum particles enhanced with graphene fluoride","authors":"Siyi Zhang ,&nbsp;Jingxuan Li ,&nbsp;Yu Tian ,&nbsp;Shen Fang ,&nbsp;Chao Li ,&nbsp;Xilong Yu ,&nbsp;Yue Jiang ,&nbsp;Lijun Yang","doi":"10.1016/j.combustflame.2024.113858","DOIUrl":"10.1016/j.combustflame.2024.113858","url":null,"abstract":"<div><div>Graphene fluoride (GF) with its two-dimensional structure and high fluorine content on the surface can be used to enhance the combustion characteristics of micron-sized Aluminum (μAl) particles. However, the enhancing mechanisms of GF in Al combustion remain not fully understood. In this work, the effects of GF on combustion temperature, flame emission spectrum, ignition delay time, and condensed combustion products (CCPs) size of μAl were studied using laser ignition and optical diagnostic experiments. The combustion characteristics of GF- or polytetrafluoroethylene (PTFE)-modified μAl composite particles were compared to elucidate the ignition and combustion mechanism of different fluorides. The results show that the thermal decomposition behavior and the energy distribution among excited Al atoms differ significantly between GF and PTFE. Compared with PTFE, GF and its decomposition products have stronger excitation ability for high energy Al atoms, which is conducive to increasing the combustion temperature of particle flame. In addition, the ignition delay time and CCPs size of Al/GF are approximately 49∼66 % and 10 % less than those of Al/PTFE, respectively. These results provide a fundamental understanding and data support for the application of functionalized graphene in metal fuels and solid propellants.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"272 ","pages":"Article 113858"},"PeriodicalIF":5.8,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142704912","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":"Ignition model for solid propellants under low temperatures involving the effect of aluminum","authors":"Yanfeng Jiang ,&nbsp;Zhan Wen ,&nbsp;Tuanwei Xu ,&nbsp;Xianghua Chen ,&nbsp;Peijin Liu ,&nbsp;Wen Ao","doi":"10.1016/j.combustflame.2024.113857","DOIUrl":"10.1016/j.combustflame.2024.113857","url":null,"abstract":"<div><div>The specific impact of aluminum powder on solid propellant ignition remains unclear. Therefore, this study investigated the ignition performance of hydroxyl-terminated polybutadiene/aluminum/ammonium perchlorate composite propellants at low temperatures. Based on a solid-phase reaction, a propellant ignition model was developed by modifying aluminum, and the ignition delay times of the propellants at different initial temperatures were calculated. A reduced initial temperature of the propellant from 283 to 213 K increased the theoretical ignition delay time from 0.144 to 0.303 s, respectively. The results were confirmed by comparing the ignition delay times of the propellants at various initial temperatures obtained from laser ignition, with a deviation of ˂9.14%. The key reason for the increased ignition delay time was the increase in inert heating time, whereas the decrease in the chemical reaction rate due to the low temperature was negligible. Subsequent analyses revealed that the presence of aluminum significantly increased the thermal conductivity of the propellant, heat loss from the burning surface, and inert heating time of the propellant, thereby significantly increasing the ignition delay time of the propellant. This study provides a practical theoretical ignition model for composite propellants under low-temperature conditions.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"272 ","pages":"Article 113857"},"PeriodicalIF":5.8,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142703828","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 kinetics of alternative fuels, Part-IV: Extending reaction mechanism “DLR Concise” to include oxygenates components","authors":"Trupti Kathrotia ,&nbsp;Thomas Bierkandt ,&nbsp;Nina Gaiser ,&nbsp;Sandra Richter ,&nbsp;Fabian Lindner ,&nbsp;Sascha Jacobs ,&nbsp;Clemens Naumann ,&nbsp;Torsten Methling ,&nbsp;Patrick Oßwald ,&nbsp;Markus Köhler","doi":"10.1016/j.combustflame.2024.113841","DOIUrl":"10.1016/j.combustflame.2024.113841","url":null,"abstract":"<div><div>In our previous work on hydrocarbons (Kathrotia et al., Fuel 2021;302:120736) and jet fuels (Kathrotia et al., Fuel 2021;302:120737) the molecular fuel composition was shown to be an important aspect of understanding the fuel combustion chemistry and, more importantly, the emission behavior. In this extension, we elaborate our high-temperature jet fuel surrogate reaction mechanism (referred hereafter as DLR Concise) to include the chemical class of oxygenated hydrocarbons for transportation fuels. These oxygen containing species have been widely investigated in ground transportation fuels. With DLR Concise we aim for a flexible reaction model for alternative fuel surrogates; a single reaction model with the target application to both aviation- as well as transportation-fuels.</div><div>The main focus of this work is to describe the reaction kinetics of oxymethylene ethers (OME_x, x = 0–5) in low to high temperatures. OMEs are promising alternative fuels that can be derived from a variety of sustainable sources. The absence or reduction of C-C bonds makes them attractive for the reduction of soot precursors and soot emissions. The reaction model of OMEs presented in this work is extensively validated against wide-ranging experiments both in-house and from literature. The main purpose of the DLR Concise is to provide a reaction mechanism with a large degree in flexibility to simulate various fuel surrogates (existing and new) and predict pollutants for the fuel assessment based on fuel molecular structure.</div><div>A comprehensive model validation as well as new in-house experimental data set on C₁-C₄ alcohols and primary reference fuel (PRF90) measured in high-temperature flow reactor is available as supplemental material.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"271 ","pages":"Article 113841"},"PeriodicalIF":5.8,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142705150","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":"LT-HyChem - A physics-based chemical kinetic modeling approach for low-temperature oxidation of real fuels I: Rationale, methodology, and application to a simple fuel mixture","authors":"Rishav Choudhary,&nbsp;Pujan Biswas,&nbsp;Vivek Boddapati,&nbsp;Hai Wang,&nbsp;Ronald K. Hanson","doi":"10.1016/j.combustflame.2024.113852","DOIUrl":"10.1016/j.combustflame.2024.113852","url":null,"abstract":"<div><div>The diversity of reactivities, intermediates, and pathways associated with the low-temperature (low-T) oxidation of various component classes that constitute real fuels is perhaps the most challenging aspect of modeling their combustion chemistry. Unlike high-temperature oxidation (T &gt; 1100 K), where the combustion properties of multicomponent fuels are relatively insensitive to compositional variations, reactions governing low-T oxidation exhibit pronounced sensitivity to fuel composition. Despite the fuel specificity, intermediate formation during low-T oxidation exhibits characteristic behaviors. Combining such observations and the already mature <u>Hy</u>brid <u>Chem</u>istry (HyChem) methodology for high-temperature oxidation of real fuels [<span><span>1</span></span>], we propose a framework to develop simplified, physics-based chemical kinetic models for low-T oxidation of real fuels. The proposed model captures the complexity of low-T oxidation through concise, fuel-specific reactions whose stoichiometric parameters and rate constants are experimentally constrained. Shock tube experiments needed for constraining model parameters are identified and plausible validation targets are discussed. The present paper outlines the model's description, its underlying physical principles, and an initial application to a simple, multi-component mixture, TPRF-60. Detailed uncertainty analyses and application to three real fuels will be presented in a companion paper.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"271 ","pages":"Article 113852"},"PeriodicalIF":5.8,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142705758","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 parametric study on NO and N2O formation in ammonia-methane cofired premixed flames: Spatially resolved measurements and kinetic analysis","authors":"Qing Li ,&nbsp;Liuhao Ma ,&nbsp;Jiwei Zhou ,&nbsp;Jintao Li ,&nbsp;Fuwu Yan ,&nbsp;Jianguo Du ,&nbsp;Yu Wang","doi":"10.1016/j.combustflame.2024.113851","DOIUrl":"10.1016/j.combustflame.2024.113851","url":null,"abstract":"<div><div>Understanding the mechanism of NO<em>x</em> formation and destruction is a prerequisite for the development of effective NO<em>x</em> mitigation techniques in ammonia flames. Laboratory-scale laminar ammonia (NH₃) flames are well suited for such fundamental kinetic studies as the complex interaction between chemistry and fluid flow can be largely decoupled. However, quantitative and spatially resolved NO/N₂O concentration data in canonical laminar ammonia flames are surprisingly scarce. Such data is, on the other hand, crucial for developing and validating kinetic models for NH₃ combustion. In this regard, we developed a novel NO/N₂O measurement method combining microprobe sampling and calibration-free mid-infrared laser absorption spectroscopy and realized spatially-resolved detection with high accuracy and large dynamic ratio. The fidelity of the method has been rigorously tested before being applied to perform a comprehensive parametric study on NO and N₂O formation in NH₃-CH₄ co-fired burner-stabilized premixed flames. The effects of NH₃ fuel ratio, equivalence ratio and flame temperature on NO/N₂O formation have been experimentally determined. Corresponding numerical modelling was also performed using literature-based mechanisms to provide kinetic insights into the experimental observations. It is found that existing mechanisms generally have satisfactory predictions in fuel-lean flames; however, under fuel-rich conditions, these mechanisms overpredict NO formation but underestimate its destruction, leading to significant over-prediction. Such discrepancies were further investigated through sensitivity and reaction pathway analysis. The present study not only provides extensive spatially-resolved NO/N₂O data in ammonia flames that are urgently needed for the development and validation of NH₃ combustion mechanisms, the comparison between neat CH₄ and NH₃-cofired flames also points to the fact that traditional NO<em>x</em> mitigation techniques that are popular in combustion of hydrocarbon fuels may not be appropriate in NH₃ flames. Perhaps most interestingly, the present experimental results show an oxygen-enriched oxidizer can in some cases reduce NO emission from NH₃ flames.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"272 ","pages":"Article 113851"},"PeriodicalIF":5.8,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142653874","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":"Elucidating high-pressure chemistry in acetylene oxidation: Jet-stirred reactor experiments, pressure effects, and kinetic interpretation","authors":"Qian-Peng Wang ,&nbsp;Jing Yang ,&nbsp;Yu-Feng Xu ,&nbsp;Zi-Qiang Zhu ,&nbsp;Ling-Nan Wu ,&nbsp;Jiu-Jie Kuang ,&nbsp;Du Wang ,&nbsp;Marina Braun-Unkhoff ,&nbsp;Zhen-Yu Tian","doi":"10.1016/j.combustflame.2024.113835","DOIUrl":"10.1016/j.combustflame.2024.113835","url":null,"abstract":"<div><div>Acetylene plays a crucial role as an intermediate in the combustion of complex hydrocarbons, such as, e.g.<em>,</em> jet fuels. In this study, high-pressure acetylene oxidation has been investigated by a combination of kinetic and experimental methods using a jet-stirred reactor (JSR) in the range of 497–910 K at <em>p</em> = 24 atm. The study covered three fuel-equivalence ratios: <em>φ</em> = 0.5 (fuel-lean), <em>φ</em> = 1.0 (stoichiometric), and <em>φ</em> = 3.0 (fuel-rich). Mole fraction profiles of 10 species, including CO, CO₂, CH₄, C₂H₄, C₂H₆, C₃H₆, C₃H₈, CH₃OH, CH₃CHO, and C₃H₄O, were identified and quantified using gas chromatography (GC) and gas chromatography-mass spectrometry (GC–MS). A kinetic model for describing the high-pressure chemistry of acetylene oxidation is proposed, which well characterizes important experimental findings, such as the fuel oxidation reactivity and the speciation of crucial products. At high pressures (<em>p</em> = 24 atm), acetylene exhibits a higher fuel consumption than at lower pressures (<em>p</em> = 1 and 12 atm) because of the increased sensitivity of dehydrogenation reactions by OH radicals accelerating the oxidation of the fuel at low temperatures. Furthermore, fuel-specific intermediates are observed, including acetaldehyde, propanal, small alkanes, and alkenes. These species mainly result from H-abstraction reactions by OH following O₂-addition reactions from triple carbon bond moieties in acetylene. The formation of further products, such as carbon monoxide and carbon dioxide, is closely related to the consumption of these fuel-specific species. In particular, the formation of aromatics, such as e.g., benzene and toluene, are detected at trace levels in the current experiments due to the rapid formation and decomposition process occurring at high pressures. By analyzing the distinct kinetic behavior, it was found that acetylene was almost completely depleted at higher system pressure (<em>p</em> = 24 atm). Some intermediates are rather active and can react with O₂ and peroxides. Consequently, the high-pressure oxidation of acetylene mainly proceeds along the pathway of C<img>C → CHCHOH → HOCHO/OCHCHO → CO → CO₂ at the high-pressure chemistry (<em>p</em> = 24 atm). Overall, this study provides valuable insights into the pressure-dependent combustion behavior of acetylene and its implications for optimizing jet fuel combustion processes.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"272 ","pages":"Article 113835"},"PeriodicalIF":5.8,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142653978","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":"Simultaneous Schlieren and direct photography of detonation diffraction regimes in hydrogen mixtures","authors":"Jacob Klein,&nbsp;Omid Samimi-Abianeh","doi":"10.1016/j.combustflame.2024.113845","DOIUrl":"10.1016/j.combustflame.2024.113845","url":null,"abstract":"<div><div>The diffraction behavior of gaseous detonations through an abrupt area change is investigated using hydrogen-oxygen-nitrogen mixtures at initial pressures of 0.5 and 1.0 bar. Critical conditions are noted and detailed discussion of the differing diffraction behaviors is undertaken, supported by simultaneous Schlieren and direct photography imaging as well as pressure-based velocity measurements. The experiments reveal four distinct diffraction regimes. The subcritical outcome is characterized by transmission failure with the leading shock front decoupling from the reaction zone, seen predominantly at lower oxygen concentrations. At intermediate oxygen levels, reinitiation from reflected shock waves is consistently observed. The critical regime exhibits both subcritical and supercritical outcomes, with detonation reinitiation at the diffraction dome's head leading to localized implosions for the supercritical case. Supercritical outcomes demonstrate successful detonation transmission, maintaining the shock front and reaction zone coupling. The effects of initial conditions on the probability of successful detonation transition and diffraction are highlighted. With the use of simultaneous direct photography and Schlieren imaging techniques, previously unseen details of the detonation and diffraction processes are recorded and explained.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"272 ","pages":"Article 113845"},"PeriodicalIF":5.8,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142653976","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":"Ab initio intermolecular interactions mediate thermochemically real-fluid effects that affect system reactivity: The first application of high-order Virial EoS and first-principles multi-body potentials in trans-/super-critical autoignition modelling","authors":"Mingrui Wang ,&nbsp;Ruoyue Tang ,&nbsp;Xinrui Ren ,&nbsp;Yanqing Cui ,&nbsp;Molly Meng-Jung Li ,&nbsp;Shao-Yuan Leu ,&nbsp;Carol Sze Ki Lin ,&nbsp;Song Cheng","doi":"10.1016/j.combustflame.2024.113844","DOIUrl":"10.1016/j.combustflame.2024.113844","url":null,"abstract":"<div><div>The properties of supercritical fluids are dictated by intermolecular interactions that involve two or more molecules. Such intermolecular interactions were described via intermolecular potentials in historical supercritical combustion modeling studies, but have been treated empirically and with no consideration of radical interactions or multi-body interactions involving more than two molecules. This approach has been adopted long ago, assuming sufficient characterization of real-fluid effects during supercritical combustion. Here, with data from <em>ab initio</em> multi-body intermolecular potentials, non-empirical high-order Virial Equation of State (EoS), and real-fluid thermochemical and kinetic simulations, we reveal that empirical intermolecular potentials can lead to significant errors in representing supercritical fluids under common combustion situations, which can be impressively described by <em>ab initio</em> intermolecular potentials. These interactions are also found to greatly influence autoignition delay times, a common measure of global reactivity, with significant contributions from radical interactions and multi-body interactions. It is therefore of necessity to incorporate <em>ab initio</em> intermolecular interactions in studying supercritical combustion and various dynamic systems involving supercritical fluids, which has now been enabled through the new framework developed in the present study.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"272 ","pages":"Article 113844"},"PeriodicalIF":5.8,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142653977","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 Bayesian approach to estimate flame spread model parameters over the cylindrical PMMA samples under various gravity conditions","authors":"Shinji Nakaya ,&nbsp;Taro Takemata ,&nbsp;Yuxuan Ma ,&nbsp;Fangsi Ren ,&nbsp;Mitsuhiro Tsue","doi":"10.1016/j.combustflame.2024.113828","DOIUrl":"10.1016/j.combustflame.2024.113828","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The flammability limit of cylindrical polymethyl-methacrylate (PMMA) samples in an opposed-flow was observed experimentally under various gravity levels at 1&lt;span&gt;&lt;math&gt;&lt;mi&gt;G&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; or more utilizing a centrifuge. Flame spread on the sample was observed, and the limiting oxygen concentration (LOC) was measured in various opposed-flow velocities ranging from 5 to 30 cm/s. Two rotating radii of the centrifuge were tested to assess the effects of Coriolis force on the LOC. A scale analysis model, based on an energy balance equation, was evaluated for thermally thick cylindrical samples. The buoyancy-induced flow was modeled in the analytical model. Model parameters were evaluated with a Bayesian approach: The Metropolis Hasting (a Markov Chain Monte Carlo) method. The results indicated that flames were tilted by the Coriolis force when the oxygen concentration was sufficiently rich from the LOC in 4&lt;span&gt;&lt;math&gt;&lt;mi&gt;G&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;. However, the effects were negligible under the oxygen concentration conditions near LOC. No significant difference in the LOC was also observed even when the rotating radius of the centrifuge changed. At 1&lt;span&gt;&lt;math&gt;&lt;mi&gt;G&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; or higher, the LOC approached to a certain value asymptotically with decreasing the opposed-flow velocity. The LOC also increased with increasing the gravity level and sample diameter. The measured LOCs were used to sample model parameters using MCMC methods. Consequently, a suitable fitting curve of the model to the experimental LOC was obtained. Using the predicted model parameters, the LOC under microgravity, Moon, and Mars conditions were predicted as a function of the opposed-flow velocity. In microgravity, the LOC increased greatly with decreasing the forced flow velocity (the radiative extinction regime), and the minimum LOC (MLOC) was recognized. On Moon, the credible interval of LOC was rather large in the low-velocity region, and the MLOC was also recognized. Moreover, it was possible that the cylindrical PMMA sample exhibited the highest flammability not under microgravity but a partial gravity condition.&lt;/div&gt;&lt;div&gt;&lt;strong&gt;Novelty and Significance&lt;/strong&gt;&lt;/div&gt;&lt;div&gt;From observing the limiting oxygen concentration of the flammability limit for cylindrical polymethyl-methacrylate (PMMA) samples in opposed-flows under various gravity conditions, we developed a model of limiting oxygen concentration (LOC) for thick cylindrical samples with the buoyancy induced flow was developed, and we estimated difficult-to-predict parameters using Bayesian statistical methods. Using this model, we can estimate the flammability limits under various gravity conditions of manned space exploration, including Moon and Mars. In addition, the present study shows that the minimum limiting oxygen concentration (MLOC) is the lowest in partial gravity. These results open a new research field for partial gravity combustions, apart from the normal gravity and microgravity and c","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"272 ","pages":"Article 113828"},"PeriodicalIF":5.8,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142653875","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":"Inhibition of the oblique detonation wave detachment in two-phase n-heptane/air mixtures","authors":"Hongbo Guo ,&nbsp;Yue Sun ,&nbsp;Ruixuan Zhu ,&nbsp;Shuo Wang ,&nbsp;Majie Zhao ,&nbsp;Baolu Shi ,&nbsp;Xiao Hou","doi":"10.1016/j.combustflame.2024.113843","DOIUrl":"10.1016/j.combustflame.2024.113843","url":null,"abstract":"<div><div>In this work, oblique detonation wave propagations in <em>n</em>-heptane droplet/vapor/air mixtures induced by a wedge at high altitude and Mach number are simulated by the Eulerian-Lagrangian method with a skeletal chemical mechanism. This work is a first attempt to inhibit the detachment of oblique detonation wave (ODW) and expand the operation range of thrusters based on oblique detonation combustion in partially pre-vaporized <em>n</em>-heptane/air mixtures. Effects of gas/liquid equivalence ratios and droplet diameters are considered, and the ODW morphology is analyzed. Standing windows, ODW characteristics and predictability of detachment inhibition are discussed. First, the detonation theoretical calculation is performed at 25–40 km operation conditions for pure gas <em>n</em>-heptane/air mixtures. The results show that the wedge angle range for successful ignition, <em>i.e.</em>, standing window, increases with the increase of flight altitude and Mach number. The internal energy and kinetic energy of mixtures are affected by the wedge angle and flight Mach number, so that the maximum angle of ODW with flight conditions presents an opposite trend over or below Mach 10. The two-dimensional (2D) ODWs in our simulation scope, which are triggered by the collision of the initiation zones formed from the wedge, show a multi-wave head structure similar to normal detonation. Detachment is inhibited in partially pre-vaporized <em>n</em>-heptane/air mixtures, due to the non-explosive mixtures near triple-point and the post-ODW inter-phase mass and energy transfers by the latent heat absorption and vapor addition from droplet evaporation. Moreover, the predictability of pre-vaporized <em>n</em>-heptane on inhibiting ODW detachment is explored through the relationship of chemical and evaporation timescales. It is demonstrated that the excitation time is very small approaching the detachment condition where an abrupt ODW tends to form. Accordingly, when the ratio of droplet heat absorption time to evaporation time is relatively high, <em>i.e., τ_h</em> / (<em>τ_ev</em>)^1/2 &gt; 0.01, the ODW detachment is more likely to be inhibited.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"272 ","pages":"Article 113843"},"PeriodicalIF":5.8,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142653979","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}