Flow, Turbulence and Combustion最新文献

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Numerical Investigation of Hypergolic Combustion and Wall Thermal Loading in a High-Thrust Multi-Element Lunar Lander Thruster 高推力多单元月球着陆器自燃与壁面热载荷数值研究
IF 2.2 3区 工程技术
Flow, Turbulence and Combustion Pub Date : 2026-09-11 DOI: 10.1007/s10494-026-00792-6
S. Mathankumar, Abhishek Sharma, Varghese Mathew Thannickal, Snehasish Panigrahy
{"title":"Numerical Investigation of Hypergolic Combustion and Wall Thermal Loading in a High-Thrust Multi-Element Lunar Lander Thruster","authors":"S. Mathankumar,&nbsp;Abhishek Sharma,&nbsp;Varghese Mathew Thannickal,&nbsp;Snehasish Panigrahy","doi":"10.1007/s10494-026-00792-6","DOIUrl":"10.1007/s10494-026-00792-6","url":null,"abstract":"<div><p>A multi-payload lunar lander may require a high-thrust hypergolic propulsion system employing multiple injector elements in its thrusters, instead of the conventionally used single-element injector configuration. Multi-element hypergolic thrusters exhibit complex spray-spray interactions that strongly influence near-wall combustion and thermal loading. In this work, a coupled Eulerian-Lagrangian numerical methodology is developed to investigate spray-combustion-thermal interactions in a multi-element MMH-NTO thruster. The model combines Lagrangian droplet tracking, global and reduced finite-rate chemical kinetics, spray-wall interaction, and conjugate heat transfer to predict the flame structure and the thermal response of the thruster walls. The methodology is first validated against experimental wall-temperature data from an orbital-class thruster, showing good agreement. It is then applied to a high-thrust multi-element lunar lander thruster to examine the effects of injector interactions. Strong interactions between neighbouring swirl injector elements are found to disrupt continuous near-wall MMH deposition, producing spatially intermittent droplet impingement and non-uniform evaporative cooling along the chamber wall. The simulations capture pronounced azimuthal heat-flux variations and characteristic petal-shaped thermal patterns, consistent with hot-test observations. Under 50% throttled operation, reduced injection momentum causes spray-cone collapse, longer near-wall residence times, and increased evaporation, resulting in lower wall temperatures than under nominal operating conditions. The study demonstrates the importance of multi-element spray interactions in governing thermal asymmetry in hypergolic thrusters and provides a computationally efficient tool for predicting wall heat loads under mission-relevant operating conditions.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"117 3","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148927688","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Effects of Hydrogen/Diesel Mixing Ratio on Coupled Combustion and Piston Dynamics in a Hydrogen Vibration Combustion Alternator 氢柴油混合比对氢振动燃烧交流发电机耦合燃烧和活塞动力学的影响
IF 2.2 3区 工程技术
Flow, Turbulence and Combustion Pub Date : 2026-09-11 DOI: 10.1007/s10494-026-00791-7
Yepei Zhang, Qinglong Wu, Junlin Bai, Mengyang Yang, Chenheng Yuan
{"title":"Effects of Hydrogen/Diesel Mixing Ratio on Coupled Combustion and Piston Dynamics in a Hydrogen Vibration Combustion Alternator","authors":"Yepei Zhang,&nbsp;Qinglong Wu,&nbsp;Junlin Bai,&nbsp;Mengyang Yang,&nbsp;Chenheng Yuan","doi":"10.1007/s10494-026-00791-7","DOIUrl":"10.1007/s10494-026-00791-7","url":null,"abstract":"<div><p>The hydrogen vibration combustion alternator (HVCA) is a crankless combustion system characterised by slow-compression/fast-expansion motion, in which combustion development and piston dynamics are strongly coupled. In this study, a closed-loop multiphysics numerical framework was developed by coupling a one-dimensional vibration-electromagnetic dynamics model with a three-dimensional CFD combustion model. Under a constant total chemical energy input per cycle, the hydrogen mass fraction was varied from 70% to 95% to quantify the coupled response of combustion development and piston dynamics to fuel composition. The results show that increasing the hydrogen fraction mainly reorganises the temporal structure of heat release, rather than continuously increasing the peak heat release rate. Hydrogen enrichment advances combustion phasing, shortens the overall combustion duration, and strengthens the rapid-expansion response of the piston. However, once the hydrogen fraction exceeds approximately 85%, the further reduction in combustion duration becomes limited, indicating a diminishing combustion-acceleration effect at higher hydrogen fractions. With increasing hydrogen fraction, the predicted soot formation gradually decreases, whereas the mean NO mass fraction exhibits a non-monotonic variation and reaches its maximum at a hydrogen fraction of 85%. Under the present operating conditions, a hydrogen fraction of 85%–90% provides a practical compromise among combustion concentration, piston dynamic response, and emission behaviour.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"117 3","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148927676","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Revisiting the Law of the Wall in Fully Developed Turbulent Pipe and Channel Flows: A Compact Leading-Order and Explicit Reconstruction From Overlooked Phenomenological Insights and Freely Available Data 在完全发展的湍流管道和通道流动中重新审视壁面规律:从被忽视的现象学见解和可自由获得的数据中得到紧凑的领先顺序和明确的重建
IF 2.2 3区 工程技术
Flow, Turbulence and Combustion Pub Date : 2026-09-07 DOI: 10.1007/s10494-026-00788-2
Juan A. Medina Méndez, Heiko Schmidt
{"title":"Revisiting the Law of the Wall in Fully Developed Turbulent Pipe and Channel Flows: A Compact Leading-Order and Explicit Reconstruction From Overlooked Phenomenological Insights and Freely Available Data","authors":"Juan A. Medina Méndez,&nbsp;Heiko Schmidt","doi":"10.1007/s10494-026-00788-2","DOIUrl":"10.1007/s10494-026-00788-2","url":null,"abstract":"<div><p>Motivated by increasing open access of direct numerical simulation (DNS) and experimental data, we discuss potentially overlooked phenomenological issues related to the formulation of a leading-order reconstruction of the law of the wall (LoW) in fully developed turbulent channel and pipe flows of constant fluid properties. Most of these issues relate to seemingly asymptotic constants or scalings evidenced in the available DNS data. These allow the derivation of a classical layer-based fit for the LoW of the mean velocity profile (MVP) in a clean and straightforward way. For low-to-moderate Reynolds number flows, the inherent empiricism due to incomplete similarity is handled by the specification of additional data-based correlations. As an example, the centerline velocity is required for the full specification of the MVP-LoW. We also discuss a novel layer-based fit for the wall-normal profiles of the turbulence kinetic energy (TKE) and the TKE-dissipation rate. The latter fits are mostly derived from DNS data, although we offer a series of novel insights, and we derive an overlooked scaling of the turbulence frequency which is related to our MVP-LoW. We consider the layer-wise LoW to be of relevance for the understanding of wall-bounded turbulence. Its closed and explicit form relying on very simple linear or quasi-linear fits renders it appealing for implementation in coarsely resolved Reynolds-Averaged Navier-Stokes (RANS) models for turbulent pipe and channel flows.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"117 3","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10494-026-00788-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148903637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Aerodynamic Characteristics Analysis of High-Speed Train Pantograph Under Various Crosswind and Train Speed Conditions 不同侧风和列车速度条件下高速列车受电弓气动特性分析
IF 2.2 3区 工程技术
Flow, Turbulence and Combustion Pub Date : 2026-08-25 DOI: 10.1007/s10494-026-00787-3
Peilin Gong, Zhuojun Li, Yuhan Guo, Huapu Song, Chunjiang Chen, Fentian Zhu, Yang Chen, Kailong Jin, Sijun Huang, Huadong Yao, Shuoguo Zhang, Jiqiang Niu
{"title":"Aerodynamic Characteristics Analysis of High-Speed Train Pantograph Under Various Crosswind and Train Speed Conditions","authors":"Peilin Gong,&nbsp;Zhuojun Li,&nbsp;Yuhan Guo,&nbsp;Huapu Song,&nbsp;Chunjiang Chen,&nbsp;Fentian Zhu,&nbsp;Yang Chen,&nbsp;Kailong Jin,&nbsp;Sijun Huang,&nbsp;Huadong Yao,&nbsp;Shuoguo Zhang,&nbsp;Jiqiang Niu","doi":"10.1007/s10494-026-00787-3","DOIUrl":"10.1007/s10494-026-00787-3","url":null,"abstract":"<div><p>As train speeds increase, the aerodynamic challenges posed by the complex and variable characteristics of higher-speed pantographs under different operating conditions and crosswind speeds became more pronounced. These challenges significantly compromised the stability of the pantograph, jeopardizing the safety of train operations. This study aimed to investigate the impact of various operating conditions of higher-speed pantographs, train speeds, and crosswind conditions on the unsteady aerodynamic characteristics of pantographs. Numerical simulations were conducted using the improved delayed detached-eddy simulation (IDDES) method, and the results were validated against wind tunnel test data. The results indicated that the operational orientation of the pantograph exerted a profound influence on its aerodynamic behavior. While the pantograph generated a higher aerodynamic uplift force in the knuckle-downstream direction, this lift exhibited more pronounced fluctuations in the knuckle-upstream direction, accompanied by more intricate component load characteristics and the evolution of more complex vortex structures. As the train’s speed increased, the lift and drag coefficients of the lower framework of the pantograph demonstrated a pronounced sensitivity to speed variations, with its average drag coefficients surpassing that of the upper frameworkwork. Simultaneously, vortex shedding phenomena in the critical regions of the pantograph’s flow field exhibited a direct correlation with speed, with both the magnitude and intensity of the coherent structures escalating substantially. The flow field within the wake region beneath the pantograph emerged as the most complex due to the interference from the wake structures of multiple components. As crosswind velocity intensified, the lift and drag coefficients of each pantograph components underwent nonlinear, abrupt transitions with increasing wind speed. Notably, significant transitions occurred at a crosswind velocity of 10 m/s. At higher crosswind speeds, the wake vortex system in the pantograph’s flow field exhibited increasingly pronounced deflection and superposition effects, further complicating the overall flow structure.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"117 2","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148837931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
PIV Analysis of Flow Dynamics and Crystal Motion During Solidification of an Aqueous Ammonium Chloride-Water Solution in a Large Containment 大容器中氯化铵水溶液凝固过程中流动动力学和晶体运动的PIV分析
IF 2.2 3区 工程技术
Flow, Turbulence and Combustion Pub Date : 2026-08-24 DOI: 10.1007/s10494-026-00786-4
Gloshan Shayesteh, Andreas Ludwig, Mihaela Stefan-Kharicha, Menghuai Wu, Abdellah Kharicha
{"title":"PIV Analysis of Flow Dynamics and Crystal Motion During Solidification of an Aqueous Ammonium Chloride-Water Solution in a Large Containment","authors":"Gloshan Shayesteh,&nbsp;Andreas Ludwig,&nbsp;Mihaela Stefan-Kharicha,&nbsp;Menghuai Wu,&nbsp;Abdellah Kharicha","doi":"10.1007/s10494-026-00786-4","DOIUrl":"10.1007/s10494-026-00786-4","url":null,"abstract":"<div><p>A dual-phase Particle Image Velocimetry (DPVI) technology is employed to capture the velocity fields of both the liquid and equiaxed crystals, enabling a quantitative analysis of the solidification dynamics of an aqueous ammonium chloride-water solution within a containment system of unprecedented size, a scale that has not been previously reported in the literature. Due to the large dimensions of the containment, several key phenomena occur, including (i) flow channels in the columnar mushy layers, (ii) unsteadily sedimenting of equiaxed crystals, (iii) agglomerations of crystals that collapse when they grow too large, resulting in crystal avalanches, and (iv) flow stratification driven by double-diffusive convection. The last-mentioned phenomenon was observed not only at the end of the process, starting from the top of the containment, but also as an intermediate occurrence in the middle of the test cell. It terminates when the dynamics of equiaxed crystal become too intense, and the turbulent kinetic energy increases significantly. The DPIV measurements provide a quantitative description of these complex processes, which could contribute to the development of future numerical models.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"117 2","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10494-026-00786-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148837360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Laminarization Mechanism of Near-Wall Turbulence in Premixed Natural Gas Combustion Investigated by Direct Numerical Simulation 直接数值模拟研究了预混天然气燃烧中近壁湍流层叠化机理
IF 2.2 3区 工程技术
Flow, Turbulence and Combustion Pub Date : 2026-08-10 DOI: 10.1007/s10494-026-00783-7
Takashi Ohta, Yuga Nagai, Yasuyuki Sakai, Genki Ueno
{"title":"Laminarization Mechanism of Near-Wall Turbulence in Premixed Natural Gas Combustion Investigated by Direct Numerical Simulation","authors":"Takashi Ohta,&nbsp;Yuga Nagai,&nbsp;Yasuyuki Sakai,&nbsp;Genki Ueno","doi":"10.1007/s10494-026-00783-7","DOIUrl":"10.1007/s10494-026-00783-7","url":null,"abstract":"<div><p>In this study, we clarified the characteristics of flame propagation during combustion and the mechanism of laminarization resulting from the attenuation of turbulence structures in the flow field under the influence of the flame. We performed three-dimensional simulations of the wall turbulence in the combustion of premixed natural gas and premixed hydrogen. We adopted a direct numerical simulation method for compressible flow with combustion using a reaction model. Premixed natural gas and premixed hydrogen combustion have different laminarization mechanisms in turbulent combustion fields. The heat of the flame affects the velocity streaks and vortices of the turbulence structures differently, and changes in the wall shear stress and wall heat flux exhibit different tendencies. Depending on the thermal Péclet number, defined using the maximum local intensity of turbulence as a parameter for classifying the characteristics of the laminarization mechanism of the flow field, the wall shear stress may change before the wall heat flux, or both may change simultaneously, under the influence of combustion. The aforementioned results provide insights into the prediction and control of turbulent combustion for future applications.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"117 2","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10494-026-00783-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148751407","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Increased Flashback Propensity in Simple, Perfectly Premixed, Laminar Thermoacoustic Hydrogen Systems 在简单、完美预混、层流热声氢系统中增加闪回倾向
IF 2.2 3区 工程技术
Flow, Turbulence and Combustion Pub Date : 2026-08-06 DOI: 10.1007/s10494-026-00785-5
Adriano Bordoni, Antonio J. Torregrosa, Alberto Broatch, Jorge García-Tíscar
{"title":"Increased Flashback Propensity in Simple, Perfectly Premixed, Laminar Thermoacoustic Hydrogen Systems","authors":"Adriano Bordoni,&nbsp;Antonio J. Torregrosa,&nbsp;Alberto Broatch,&nbsp;Jorge García-Tíscar","doi":"10.1007/s10494-026-00785-5","DOIUrl":"10.1007/s10494-026-00785-5","url":null,"abstract":"<div><p>The use of hydrogen to enrich or replace hydrocarbon-based flames represents an appealing perspective to reduce the emission of pollutants in gas turbine combustors. This implementation is, however, not straightforward, as the properties of hydrogen consistently differ from those of the most widely used fuels, resulting in a change in the combustion stability of the mixture. This work investigates the non-linear thermoacoustic stability of a simple Rijke tube containing a perfectly premixed, laminar, conical flame fed by either a pure methane-based mixture or a hydrogen-enriched one. The mean heat release rate and the geometry of the system were kept constant for both mixtures. Flame dynamics were modelled using a Level Set Method, from which a Flame Describing Function was derived for each mixture and coupled with a one-dimensional acoustic model within a low-order thermoacoustic framework to asses the stability of the system. The hydrogen-enriched flame was found to exhibit a weaker non-linear response than the methane-based flame, in agreement with previous observations reported in the literature. This behaviour was attributed to the higher unstretched laminar flame speed of the hydrogen-enriched mixture, which enhances the resilience of the flame front to develop geometric non-linearities following an acoustic perturbation, reducing its tendency towards heat release rate saturation. As a consequence, the hydrogen-enriched system generated larger thermoacoustic oscillations and ultimately experienced flashback, whereas the methane-based configuration remained bounded by more consistent non-linear saturation effects.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"117 2","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148751113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Liquid Water Addition as an Emission Control Strategy for Ammonia Flames: A High-Fidelity Numerical Study 添加液态水作为氨火焰排放控制策略:高保真数值研究
IF 2.2 3区 工程技术
Flow, Turbulence and Combustion Pub Date : 2026-08-05 DOI: 10.1007/s10494-026-00780-w
Riccardo Concetti, Maximilian Bambauer, Federica Ferraro, Josef Hasslberger, Markus Klein
{"title":"Liquid Water Addition as an Emission Control Strategy for Ammonia Flames: A High-Fidelity Numerical Study","authors":"Riccardo Concetti,&nbsp;Maximilian Bambauer,&nbsp;Federica Ferraro,&nbsp;Josef Hasslberger,&nbsp;Markus Klein","doi":"10.1007/s10494-026-00780-w","DOIUrl":"10.1007/s10494-026-00780-w","url":null,"abstract":"<div><p>The mitigation of nitrogen oxide (<span>(textrm{NO}_x)</span>) emissions remains a key challenge for the use of ammonia as a carbon-free energy carrier. In contrast to hydrogen, ammonia combustion is inherently prone to fuel-<span>(textrm{NO}_x)</span> formation due to the nitrogen content of the fuel, limiting the effectiveness of purely temperature-based mitigation strategies. In this work, liquid water addition is investigated as a potential emission control approach for premixed ammonia/air flames using high-fidelity numerical simulations. A hybrid Eulerian–Lagrangian framework is employed to resolve the interaction between a spherically expanding quasi-laminar ammonia flame and evaporating water droplets. The influence of droplet sizes on flame propagation, flame thickness, and emission behavior is examined under stoichiometric conditions. Water addition is found to reduce the burning rate per unit area and increase flame thickness through combined thermal and dilution effects, while having a limited impact on flame surface wrinkling. Both small and large droplets lead to a significant reduction in NO formation, with large droplets producing localized regions of strong suppression and small droplets yielding a more spatially uniform reduction. Analysis of intermediate nitrogen species indicates a minor contribution of the <span>(textrm{N}_{2}textrm{O})</span> pathway under the present conditions, while thermal and fuel-<span>(textrm{NO}_x)</span> pathways remain sensitive to water-induced temperature changes. These results provide physical insight into the coupling between water evaporation, flame structure, and <span>(textrm{NO}_x)</span> formation in premixed ammonia flames.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"117 2","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10494-026-00780-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148750547","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Statistical Analysis and RSM Optimization of Combustion and Emission Characteristics in an RCCI Engine Fueled with Macroalgal Biodiesel and Iso-butanol 以大藻生物柴油和异丁醇为燃料的RCCI发动机燃烧和排放特性的统计分析及RSM优化
IF 2.2 3区 工程技术
Flow, Turbulence and Combustion Pub Date : 2026-07-30 DOI: 10.1007/s10494-026-00784-6
Ajmeera Naresh, Ravi Kumar Puli
{"title":"Statistical Analysis and RSM Optimization of Combustion and Emission Characteristics in an RCCI Engine Fueled with Macroalgal Biodiesel and Iso-butanol","authors":"Ajmeera Naresh,&nbsp;Ravi Kumar Puli","doi":"10.1007/s10494-026-00784-6","DOIUrl":"10.1007/s10494-026-00784-6","url":null,"abstract":"<div><p>This study presents a robust multi-objective optimization framework for Reactivity Controlled Compression Ignition (RCCI) engines using a ternary blend of Ulva fasciata macroalga biodiesel and isobutanol. Employing Response Surface Methodology (RSM) integrated with Design of Experiments (DoE), the framework elucidates the nonlinear, coupled effects of isobutanol fraction, Exhaust Gas Recirculation (EGR) rates, and engine load on dual-fuel reactivity. Predictive models were rigorously validated via Analysis of Variance (ANOVA), enabling high-fidelity mapping of the engine’s operational envelope and thermodynamic behaviors. Optimized conditions (10–30%) isobutanol fraction, 5% EGR, and 12 kg load yielded a Brake Thermal Efficiency (BTE) of 31.1% (7.3% improvement over baseline diesel) and a 33% reduction in Brake Specific Fuel Consumption (BSFC). Emissions analysis revealed a 35.2% drop in <i>NOx</i>, driven by EGR’s thermal dilution and heat capacity effects, despite marginal increases in unburned Hydrocarbons 1.9% and Carbon Monoxide 2.3% from low-temperature combustion. These results highlight the potential of Ulva fasciata biodiesel-isobutanol blends for efficient, low-emission RCCI operation, advancing sustainable engine technologies.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"117 2","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148614685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Effect of Nanosecond Plasma Preconditioning on Detonation in High-Pressure H₂/O₂ Mixtures: A Multiscale Numerical Study 纳秒等离子体预处理对高压H /O混合物爆轰的影响:多尺度数值研究
IF 2.2 3区 工程技术
Flow, Turbulence and Combustion Pub Date : 2026-07-30 DOI: 10.1007/s10494-026-00782-8
Giacomo Cinieri, Zubair Ali Shah, Ghazanfar Mehdi, Maria Grazia De Giorgi
{"title":"Effect of Nanosecond Plasma Preconditioning on Detonation in High-Pressure H₂/O₂ Mixtures: A Multiscale Numerical Study","authors":"Giacomo Cinieri,&nbsp;Zubair Ali Shah,&nbsp;Ghazanfar Mehdi,&nbsp;Maria Grazia De Giorgi","doi":"10.1007/s10494-026-00782-8","DOIUrl":"10.1007/s10494-026-00782-8","url":null,"abstract":"<div><p>This work investigates the effect of nanosecond-plasma preconditioning on detonation in high-pressure hydrogen-oxygen mixtures through a multiscale numerical framework coupling zero-dimensional plasma kinetics, one-dimensional ZND detonation analysis, and two-dimensional reactive CFD. ChemPlasKin is used to compute the post-discharge thermochemical state of hydrogen oxygen mixtures, which is then mapped at the end of the afterglow as the initial condition for both ZND and CFD calculations. Parametric analyses are performed at 10 bar over reduced electric field (140–260 Td), deposited energy (25–150 mJ/cm<sup>3</sup>), and equivalence ratio (0.2–1.2). The ZND results show that non-equilibrium plasma discharge has little effect under lean conditions, whereas for ϕ ≥0.8 it shortens the induction length and reduces the predicted detonation cell size by up to 30%. In addition, the threshold reduced electric field required to produce a measurable plasma effect increases by approximately 40 Td for every 0.4 decrease in equivalence ratio. A complementary multi-pulse analysis shows that pulse repetition is effective mainly when the deposited energy per pulse is kept constant, while redistributing the same total energy over a larger number of weaker pulses yields only a limited additional benefit. The sensitivity analysis shows that the dominant control of detonation cell size remains associated with the main hydrogen branching reaction H + O2 ≤&gt;O + OH in both clean and plasma-treated mixtures. At higher pulse energy, the sensitivity pattern changes markedly, with the HO<sub>2</sub>/H<sub>2</sub>O<sub>2</sub> submechanism becoming significantly more influential. Two-dimensional DDT simulations in a 0.9 mm channel confirm that these thermochemical modifications strongly accelerate the transition, reducing the run-up distance and onset time from 68.5 mm and 136 μs in the untreated case to 9.7 mm and 17.5 μs in the most activated configuration. Overall, the results show that nanosecond plasma preconditioning can substantially compress detonation scales and promote faster DDT for high-pressure hydrogen-oxygen microdevices.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"117 2","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10494-026-00782-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148614687","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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