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Dynamics of bursting droplets from surfacing bubble plumes 表面气泡羽流中破裂液滴的动力学
IF 3.3 2区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2026-02-01 Epub Date: 2025-12-12 DOI: 10.1016/j.expthermflusci.2025.111680
Jitae Do , Binbin Wang
The dynamics of bursting droplets from surface bubbles is an important mechanism for water-to-air transport of small particles and contaminants. We investigated bubble-bursting droplets from bubble plumes, released from an air stone (AS) or a single nozzle (SN) at four gas flow rates ranging from 0.1 to 0.8 L min−1. Quantitative imaging was used to analyze the statistics of size and velocity distributions for rising bubbles and droplets ejected by bursting bubbles. Significantly greater droplet number, mass flow rate, and median size were observed in AS, by factors of 20, 8.6, and 1.8 compared to SN, reflecting the influence of subsurface bubble characteristics on droplet production. Log-normal distributions fit well to droplet size and velocity distribution regardless of the release mechanism. The characteristic median sizes show a bubble–droplet relationship of RdRb1.4, which implies Bond number relationship of BodBob1.4 under constant fluid properties. Scaling analysis using visco-capillary length and capillary velocity shows LadCad1.4, suggesting a universal scaling relationship for bursting droplets from surfacing of single bubble and bubble plumes. Involving both length and velocity scales of bubbles and droplets shows Frd(BobWeb)0.3, a scaling relationship potentially used for predicting droplet dynamics from bursting bubble plumes. These findings provide the first quantitative scaling linking bubble plume and bursting droplet dynamics, with potential applications in aerosol generation, wastewater aeration, and ocean–atmosphere mass-exchange studies.
表面气泡破裂液滴的动力学是小颗粒和污染物从水到空气传输的重要机制。我们研究了气泡柱中的气泡破裂液滴,从气石(AS)或单喷嘴(SN)中以0.1至0.8 L min - 1的四种气体流速释放。利用定量成像技术对气泡上升和气泡破裂喷射出的液滴的大小和速度分布进行统计分析。与SN相比,AS的液滴数量、质量流量和中位数尺寸分别是20倍、8.6倍和1.8倍,这反映了地下气泡特性对液滴产生的影响。无论释放机制如何,对数正态分布都能很好地适应液滴大小和速度分布。特征中值尺寸表现为Rd ~ Rb1.4的气泡-液滴关系,这意味着恒定流体性质下Bod ~ Bob1.4的键数关系。用粘度-毛细长度和毛细速度进行的结垢分析显示Lad ~ Cad−1.4,表明单泡表面和泡柱表面的破裂液滴具有普遍的结垢关系。涉及气泡和液滴的长度和速度尺度显示为Frd ~ (BobWeb)−0.3,这一尺度关系可能用于预测气泡羽流破裂时的液滴动力学。这些发现首次提供了气泡羽流和破裂液滴动力学之间的定量尺度联系,在气溶胶产生、废水曝气和海洋-大气质量交换研究中具有潜在的应用前景。
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引用次数: 0
Consecutive water entries of two side-by-side spheres: cavity interference and surface closure characteristics 两个并排球体的连续入水:空腔干涉和表面闭合特征
IF 3.3 2区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2026-02-01 Epub Date: 2025-12-13 DOI: 10.1016/j.expthermflusci.2025.111684
Xu Wang , Xujian Lyu , Hui Tang , Chao Qi , Ruisheng Sun
This paper presents an experimental investigation into cavity interference and surface closure characteristics of two side-by-side spheres undergoing consecutive water entries. A high-speed imaging system was employed to capture the dynamic processes of the two cavities, including the cavity elongation and their interaction with the free surface during the closure stage. Four distinct interference modes—rebound, expansion, tail, and bubble-dominated—are found primarily depending on the time interval between the two water entries, Δt, while showing little sensitivity to the lateral distance. Unlike the single-cavity closure, the following cavity, subject to interference, undergoes two separate detachment events from the free surface, characterized by a closure angle (defined as the acute angle between the cavity tail-end face and the free surface) whose magnitude and orientation scale with Δt. Statistical analysis indicates that the initial detachment time is independent of the adjacent cavity’s evolution, whereas the emergence of a closure angle significantly prolongs the complete detachment time and increases cavity length, especially at smaller lateral distances.
本文对两个相邻球体连续进水时的空腔干涉和表面闭合特性进行了实验研究。利用高速成像系统捕捉了两个空腔的动态过程,包括空腔的延伸及其在闭合阶段与自由表面的相互作用。四种不同的干涉模式——回弹、膨胀、尾部和气泡主导——主要取决于两次进水之间的时间间隔Δt,而对侧向距离的敏感性很小。与单腔封闭不同,受干涉影响的下腔从自由面分离两次,其特征为封闭角(定义为腔尾端面与自由面之间的锐角),其大小和方向以Δt表示。统计分析表明,初始脱离时间与邻近空腔的演变无关,而闭合角的出现显著延长了完全脱离时间,增加了空腔长度,特别是在较小的横向距离上。
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引用次数: 0
Intermittent two-phase flow characterization using advanced diagnostics in a high-pressure large-diameter slightly upward inclined pipe 采用先进的诊断技术对高压大直径微向上倾斜管道中的间歇两相流进行表征
IF 3.3 2区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2026-02-01 Epub Date: 2025-12-21 DOI: 10.1016/j.expthermflusci.2025.111683
Ahmed Aql , E. Al-Safran , E. Pereyra , C. Sarica
This study experimentally investigates slug flow characteristics under high-pressure conditions of 2.76 MPa (400 psi) in a 2° upward-inclined, large ID pipe with an internal diameter of 156 mm (6.1 in.), using advanced diagnostic instruments, including high-resolution wire-mesh sensors and a high-speed visualization system. The tests are performed within a broad range of superficial liquid and gas velocities of vSL = 0.01–0.35 m/s, and vSG = 1.3–2.5 m/s, allowing investigation of operational and topological features, such as film reversal and interfacial roughness, and enabling the distinction between slug and pseudo-slug flow. It is found that the strength of the hydraulic seal in the flow structure (slug and pseudo-slug) body governs the characteristics of the intermittent flow. In addition, the superficial liquid velocity vSL is found to be the major contributor to the formation and stability of the hydraulic seal, followed by the superficial gas velocity vSG. Specifically, the mean slug length, LS, and slug frequency, fS, are significantly influenced by superficial liquid velocity. For example, increasing vSL promotes longer and more frequent slugs, while the impact of superficial gas velocity on slug flow characteristics depends on the structure body liquid holdup, and hydraulic seal integrity. Overall, superficial gas velocity predominantly decreases liquid holdup in slug and film regions, due to high interfacial shear stress and film thinning.
本研究通过实验研究了在2.76 MPa (400 psi)高压条件下,在2°上斜、内径为156 mm (6.1 in)的大内径管道中,使用先进的诊断仪器,包括高分辨率金属丝网传感器和高速可视化系统的段塞流特性。测试在宽范围内进行,表面液体和气体速度vSL = 0.01-0.35 m/s, vSG = 1.3-2.5 m/s,允许研究操作和拓扑特征,如膜反转和界面粗糙度,并能够区分段塞流和伪段塞流。研究发现,流动结构(段塞和伪段塞)体中液压密封的强度决定了间歇流动的特性。此外,液面流速vSL是影响液压密封形成和稳定的主要因素,其次是气面流速vSG。具体来说,平均段塞长度LS和段塞频率fS受到表面液体速度的显著影响。例如,增加vSL会增加段塞流的时间和频率,而表面气体速度对段塞流特性的影响取决于结构体的含液率和液压密封的完整性。总的来说,由于高界面剪切应力和膜变薄,表面气速主要降低了段塞段和膜区域的液含率。
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引用次数: 0
Collisions between droplets of liquids of different viscosity and composite fuel particles 不同粘度液体液滴与复合燃料颗粒之间的碰撞
IF 3.3 2区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2026-02-01 Epub Date: 2025-12-05 DOI: 10.1016/j.expthermflusci.2025.111669
Anastasia Islamova, Pavel Tkachenko, Nikita Shlegel, Stanislav Shulyaev, Pavel Strizhak
It is important to understand the physics of liquid droplet collisions for a variety of applications ranging from inkjet printing to composite fuel combustion. The use of composite fuels is associated with some challenges and limitations. It is necessary to study the collisions of droplets and particles used as slurry fuel components. The selected objects of research were water and oil droplets, as well as particles of pine, cedar, coal and filter cake. Typical collision regimes (agglomeration and destruction) were identified. The characteristics of child droplets and conditions of their interaction with droplets and particles were determined. Differences between the characteristics of interaction of combustible and noncombustible component droplets with particles were detected. Equations were presented for a mathematical description of transition boundaries between regimes on maps taking account of the dimensionless linear impact parameter, the Weber number and the Ohnesorge number. The decisive factor for agglomeration or separation of droplets and particles was the properties of liquid. If a particle was pre-wetted, the type and condition of its surface did not have a significant effect on interaction regimes. The occurrence of a regime was also found to depend on the particle shape. A comparison of interaction regime maps for liquid droplets and biomass particles in the experiments with water and motor oil revealed that the separation boundary for oil shifted towards 18–27 % higher Weber numbers. This is accounted for by the physical properties of the investigated liquids. Guidelines on using the research findings in the development of secondary atomization technologies of fuel droplets were provided.
从喷墨打印到复合燃料燃烧,了解液滴碰撞的物理特性非常重要。复合燃料的使用伴随着一些挑战和限制。液滴与颗粒作为浆液燃料组分,有必要对其碰撞进行研究。选取的研究对象为水滴和油滴,以及松、雪松、煤和滤饼的颗粒。确定了典型的碰撞机制(团聚和破坏)。确定了儿童液滴的特征及其与液滴和颗粒相互作用的条件。检测了可燃组分液滴与不可燃组分液滴与颗粒相互作用特性的差异。考虑了无因次线性冲击参数、Weber数和Ohnesorge数,给出了地图上区域间过渡边界的数学描述方程。液滴和颗粒团聚或分离的决定性因素是液体的性质。如果颗粒被预湿,其表面的类型和条件对相互作用机制没有显著影响。我们还发现,一个状态的出现与粒子的形状有关。在水和机油实验中,对液滴和生物质颗粒的相互作用谱图进行比较,发现油的分离边界向韦伯数高18 - 27%的方向移动。这是由所研究液体的物理性质来解释的。提出了将研究成果应用于燃料液滴二次雾化技术开发的指导方针。
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引用次数: 0
Drag estimation for isolated, surface-mounted, droplet-inspired geometries and the effect of boundary layer parameters on flow development 孤立、表面安装、液滴启发几何的阻力估计及边界层参数对流动发展的影响
IF 3.3 2区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2026-01-30 Epub Date: 2025-11-20 DOI: 10.1016/j.expthermflusci.2025.111662
Xueqing Zhang, Burak A. Tuna, Serhiy Yarusevych, Sean D. Peterson
This study investigates flow development over three-dimensional droplet-inspired models submerged in a boundary layer using particle image velocimetry (PIV). Aerodynamic drag is estimated from stereoscopic PIV measurements performed in multiple planes in a laminar boundary layer regime for a Reynolds number based on obstacle height of Reh2070 and a relative droplet submergence in the boundary layer of δ/h=1.0. Three geometries are considered: a sessile droplet, a droplet on the verge of runback (depinning), and a hemisphere for baseline comparison with prior studies. The drag coefficients of the sessile and runback models are CD0.33 and 0.35, respectively. Although the difference in drag coefficients between the two droplet configurations is modest, the runback model demonstrates a reduction in drag force proportional to its reduced frontal area. The effects of relative submergence and boundary layer regime on flow development and wake dynamics are further examined at δ/h=1.0 and 1.4 for laminar boundary layers, and δ/h=1.5, 2.0, and 3.5 for turbulent boundary layers based on time-resolved PIV measurements in the symmetry plane of the models. The results reveal notable effect of model submergence on the wake topology and dynamics. A turbulent incoming boundary layer delays separation from the protuberance in comparison with laminar flow conditions, thus altering the wake dynamics. Spectral and modal analysis using proper orthogonal decomposition provides further insight into the attendant dominant coherent structures and the associated dynamic loading and response of the droplets close to depinning conditions.
本研究利用粒子图像测速技术(PIV)研究了浸没在边界层中的三维液滴模型的流动发展。基于障碍物高度Reh≈2070和液滴在边界层的相对浸没δ/h=1.0的雷诺数,在层流边界层条件下,在多个平面上进行立体PIV测量来估算气动阻力。考虑了三种几何形状:无底座液滴,在退落(脱屑)边缘的液滴,以及与先前研究进行基线比较的半球。固定式和回流式模型的阻力系数分别为CD≈0.33和0.35。尽管两种液滴形态之间的阻力系数差异不大,但回流模型显示阻力的减小与其减少的锋面面积成正比。在层流边界层δ/h=1.0和1.4,湍流边界层δ/h=1.5、2.0和3.5的条件下,基于模型对称面的时间分辨PIV测量,进一步研究了相对淹没度和边界层型态对流动发展和尾迹动力学的影响。结果表明,模型沉水对尾流拓扑结构和动力学有显著影响。与层流条件相比,湍流来流边界层延迟了与突起的分离,从而改变了尾迹动力学。使用适当的正交分解进行光谱和模态分析,可以进一步了解随之而来的主导相干结构以及接近脱屑条件的液滴的相关动态载荷和响应。
{"title":"Drag estimation for isolated, surface-mounted, droplet-inspired geometries and the effect of boundary layer parameters on flow development","authors":"Xueqing Zhang,&nbsp;Burak A. Tuna,&nbsp;Serhiy Yarusevych,&nbsp;Sean D. Peterson","doi":"10.1016/j.expthermflusci.2025.111662","DOIUrl":"10.1016/j.expthermflusci.2025.111662","url":null,"abstract":"<div><div>This study investigates flow development over three-dimensional droplet-inspired models submerged in a boundary layer using particle image velocimetry (PIV). Aerodynamic drag is estimated from stereoscopic PIV measurements performed in multiple planes in a laminar boundary layer regime for a Reynolds number based on obstacle height of <span><math><mrow><msub><mrow><mi>Re</mi></mrow><mrow><mi>h</mi></mrow></msub><mo>≈</mo><mn>2070</mn></mrow></math></span> and a relative droplet submergence in the boundary layer of <span><math><mrow><mi>δ</mi><mo>/</mo><mi>h</mi><mo>=</mo><mn>1</mn><mo>.</mo><mn>0</mn></mrow></math></span>. Three geometries are considered: a sessile droplet, a droplet on the verge of runback (depinning), and a hemisphere for baseline comparison with prior studies. The drag coefficients of the sessile and runback models are <span><math><mrow><msub><mrow><mi>C</mi></mrow><mrow><mi>D</mi></mrow></msub><mo>≈</mo><mn>0</mn><mo>.</mo><mn>33</mn></mrow></math></span> and 0.35, respectively. Although the difference in drag coefficients between the two droplet configurations is modest, the runback model demonstrates a reduction in drag force proportional to its reduced frontal area. The effects of relative submergence and boundary layer regime on flow development and wake dynamics are further examined at <span><math><mrow><mi>δ</mi><mo>/</mo><mi>h</mi><mo>=</mo><mn>1</mn><mo>.</mo><mn>0</mn></mrow></math></span> and 1.4 for laminar boundary layers, and <span><math><mrow><mi>δ</mi><mo>/</mo><mi>h</mi><mo>=</mo><mn>1</mn><mo>.</mo><mn>5</mn></mrow></math></span>, 2.0, and 3.5 for turbulent boundary layers based on time-resolved PIV measurements in the symmetry plane of the models. The results reveal notable effect of model submergence on the wake topology and dynamics. A turbulent incoming boundary layer delays separation from the protuberance in comparison with laminar flow conditions, thus altering the wake dynamics. Spectral and modal analysis using proper orthogonal decomposition provides further insight into the attendant dominant coherent structures and the associated dynamic loading and response of the droplets close to depinning conditions.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"172 ","pages":"Article 111662"},"PeriodicalIF":3.3,"publicationDate":"2026-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145621052","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}
引用次数: 0
Orthographic high-speed visible emission imaging of plasma jet dynamics 等离子体喷射动力学的正交高速可见发射成像
IF 3.3 2区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2026-01-30 Epub Date: 2025-11-07 DOI: 10.1016/j.expthermflusci.2025.111652
Roberto Pio Puttini , Lorenzo Capponi , Massimo Franco , Edward Mansfield , Daniel J. Bodony , Gregory S. Elliott , Gianluca Rossi , Francesco Panerai
High-enthalpy plasma jets exhibit complex, unsteady flow behavior that is critical to the development of thermal protection systems and validation of multiphysics models for non-equilibrium flow and material response. Irradiance-based diagnostics provide high-resolution spatial and temporal characterizations, enabling visualization of flow structures, temperature estimation, and instability detection. This study investigates the dynamics of an inductively coupled plasma jet, focusing on the effects of mass flow rate, torch power, and reactor pressure on jet morphology and radiative energy distribution. Using a multi-view diagnostic system based on two synchronized, orthogonal high-speed cameras, the jet behavior is resolved in space and time. The results show that increasing flow rate produces broader, less organized jet structures, while torch power and pressure strongly influence the spatial distribution of radiative energy.
高焓等离子体射流表现出复杂的非定常流动行为,这对于热保护系统的开发以及非平衡流动和材料响应的多物理场模型的验证至关重要。基于辐照度的诊断提供了高分辨率的空间和时间特征,实现了流体结构、温度估计和不稳定性检测的可视化。本文研究了电感耦合等离子体射流的动力学特性,重点研究了质量流量、火炬功率和反应器压力对射流形态和辐射能量分布的影响。利用基于两个同步、正交高速摄像机的多视点诊断系统,在空间和时间上对射流行为进行了解析。结果表明:随着流量的增加,射流结构变得更宽、更无组织,而火炬功率和压力对辐射能的空间分布影响较大;
{"title":"Orthographic high-speed visible emission imaging of plasma jet dynamics","authors":"Roberto Pio Puttini ,&nbsp;Lorenzo Capponi ,&nbsp;Massimo Franco ,&nbsp;Edward Mansfield ,&nbsp;Daniel J. Bodony ,&nbsp;Gregory S. Elliott ,&nbsp;Gianluca Rossi ,&nbsp;Francesco Panerai","doi":"10.1016/j.expthermflusci.2025.111652","DOIUrl":"10.1016/j.expthermflusci.2025.111652","url":null,"abstract":"<div><div>High-enthalpy plasma jets exhibit complex, unsteady flow behavior that is critical to the development of thermal protection systems and validation of multiphysics models for non-equilibrium flow and material response. Irradiance-based diagnostics provide high-resolution spatial and temporal characterizations, enabling visualization of flow structures, temperature estimation, and instability detection. This study investigates the dynamics of an inductively coupled plasma jet, focusing on the effects of mass flow rate, torch power, and reactor pressure on jet morphology and radiative energy distribution. Using a multi-view diagnostic system based on two synchronized, orthogonal high-speed cameras, the jet behavior is resolved in space and time. The results show that increasing flow rate produces broader, less organized jet structures, while torch power and pressure strongly influence the spatial distribution of radiative energy.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"172 ","pages":"Article 111652"},"PeriodicalIF":3.3,"publicationDate":"2026-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145463926","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}
引用次数: 0
Analysis of scour dynamics and turbulence structures at a sequence of repelling spur dikes using higher-order moments, turbulent kinetic energy fluxes, and quadrant analysis 利用高阶矩、湍流动能通量和象限分析,对排斥性直堤序列的冲刷动力学和湍流结构进行分析
IF 3.3 2区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2026-01-30 Epub Date: 2025-10-30 DOI: 10.1016/j.expthermflusci.2025.111637
Sandeep Kumar, Prashanth Reddy Hanmaiahgari
This study aims to understand local scour dynamics and turbulence characteristics around the head of repelling spur dikes by analyzing sediment bed morphology, higher-order turbulence statistics, turbulent kinetic energy fluxes, and quadrant-based turbulence events, which remain insufficiently understood in the context of these river training structures. The flow field was measured using Vectrino ADV under two Reynolds numbers (Re) of 48,508 and 42579. The sediment bed topography exhibited distinct patterns, with maximum scour depth (ds) of 0.48 h (h=flow depth) and 0.55 h at the first spur dike in both scenarios, and at the second spur dike, greater erosion occurred at a higher Reynolds number. Higher-order turbulence moments M12,M21,M30 and M03revealed ejections followed by primarily sweep, outward, and inward events near the bed. TheM03 magnitude exhibited greater variation primarily with ejection events; these phenomena were shaped by bed morphology. At both Reynolds numbers, the sweep events dominate ejection events at first and second spur dikes near-bed zone. In contrast, inward and outward events prevailed at the third spur dike. Turbulent kinetic energy flux, Fku and Fkw revealed greater magnitudes at the first and second spur dikes with dissimilarity in their sign. A significantly high vorticity is observed immediately u/s and d/s of the first spur dike throughout the depth. Quadrant analysis confirmed energetic activity near the bed zone dominated by sweep and ejection events governed turbulence structures, while the coherent structure near the water surface persisted throughout the test reach but weakened in the downstream.
本研究旨在通过分析沉积物床形态、高阶湍流统计、湍流动能通量和基于象限的湍流事件,了解在这些河流训练结构背景下仍未得到充分了解的排斥性直堤头部周围的局部冲刷动力学和湍流特征。在雷诺数Re为48,508和42579时,采用Vectrino ADV对流场进行了测量。两种情况下,第1支脉的最大冲刷深度(ds)分别为0.48 h (h=流深)和0.55 h,第2支脉的最大冲刷深度在较高雷诺数下发生较大的侵蚀。高阶湍流时刻M12,M21,M30和m03显示出抛射,随后主要是在床附近扫向,向外和向内的事件。m03星等的变化主要与喷发事件有关;这些现象是由床层形态形成的。在两种雷诺数下,在第一和第二直堤近层带处,扫射事件主导喷射事件。相比之下,在第三直堤,内向和外向的事件占主导地位。湍流动能通量、Fku和Fkw在第1和第2直堤处表现出较大的量级,但其标志不同。在整个深度处,第一直脉的u/s和d/s涡度都很高。象限分析证实,床带附近的能量活动主要由横扫和喷射事件控制湍流结构,而靠近水面的相干结构在整个测试河段持续存在,但在下游减弱。
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引用次数: 0
Analysis of non-reacting and reacting flows in biogas/methane cofiring within a double-swirl burner: role of the inner swirler 双旋流燃烧器内沼气/甲烷共燃的非反应流与反应流分析:内旋流器的作用
IF 3.3 2区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2026-01-30 Epub Date: 2025-11-15 DOI: 10.1016/j.expthermflusci.2025.111654
Ahmed M. Abdulnaim , Ahmed H. Elkholy , Mohamed Elmously , Hany A. Moneib , Ayman M. Elbaz
Environmental concerns, particularly greenhouse gas emissions, have intensified interest in renewable fuels such as biogas. However, the low reactivity of biogas presents challenges for achieving stable and efficient combustion. This study investigates the impact of inner swirl intensity on both the aerodynamic and thermal characteristics of biogas–methane cofiring in a concentric double-swirl burner. First, the influence of swirl intensity on non-reacting and reacting flow fields is analyzed using two-dimensional Particle Image Velocimetry (PIV). The study then extends to examine the effects on flame temperature distribution and exhaust emissions. Slightly rich premixed biogas/air mixtures were introduced through the inner swirl, while lean methane/air mixtures were supplied via the outer swirl. The outer swirl number was fixed at Sout = 0.49, while the inner swirl number Sin was varied (0.41, 0.72, and 1.24). Results show that increasing Sin enhances mixing and strengthens jet-to-jet interactions. A central recirculation zone (CRZ) consistently forms under all conditions, with additional outer recirculation zones appearing in non-reacting flows. In reacting cases, higher Sin reduces CRZ width while accelerating flow within it. Increased shear and vorticity at the inner shear layer enhance turbulence and sustain velocity fluctuations downstream, promoting faster mixing between fresh reactants and recirculated hot gases. Flame heat release induces radial expansion of the swirling flow and elevates turbulence intensity (Vrms), further improving mixing. These effects collectively enhance combustion efficiency, broaden the temperature field, and lead to significant reductions in CO and NO emissions. The findings highlight the effectiveness of double-swirl burners in improving biogas combustion performance and reducing their environmental impact.
环境问题,特别是温室气体排放,加强了人们对沼气等可再生燃料的兴趣。然而,沼气的低反应性给实现稳定高效燃烧带来了挑战。研究了内旋强度对沼气-甲烷同心圆双旋燃烧器共燃气动和热特性的影响。首先,利用二维粒子图像测速技术(PIV)分析了涡流强度对非反应流场和反应流场的影响。然后,研究扩展到检查火焰温度分布和废气排放的影响。通过内旋流引入略富的预混合沼气/空气混合物,而通过外旋流提供贫甲烷/空气混合物。外旋流数固定为Sout = 0.49,内旋流数Sin变化为0.41、0.72、1.24。结果表明,增加sinx可以增强混合,增强射流与射流的相互作用。在所有条件下都会形成一个中央再循环区(CRZ),在非反应流中会出现额外的外部再循环区。在反应情况下,较高的Sin减小了CRZ宽度,同时加速了其中的流动。内部剪切层的剪切和涡度增加,增强了湍流并维持了下游的速度波动,促进了新鲜反应物和再循环热气体之间更快的混合。火焰热释放引起旋流径向膨胀,提高了湍流强度,进一步改善了混合。这些效应共同提高了燃烧效率,拓宽了温度场,并显著减少了CO和NO的排放。研究结果强调了双旋流燃烧器在提高沼气燃烧性能和减少其对环境影响方面的有效性。
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引用次数: 0
Study on the de-icing performance of wind turbine blades based on PCMS-C14 coating combined with electrothermal heating 基于PCMS-C14涂层结合电热加热的风电叶片除冰性能研究
IF 3.3 2区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2026-01-30 Epub Date: 2025-11-01 DOI: 10.1016/j.expthermflusci.2025.111639
Zheng Sun , He Shen , Yiting Wang , Haotian Zheng , Fang Feng , Yan Li
Icing on wind turbine blades severely compromises turbine operation, while existing standalone anti-icing and de-icing methods exhibit inherent limitations. This study experimentally investigates the synergistic de-icing performance of wind turbine blades using the PCMS-C14 phase-change microcapsule coating, developed independently by the Wind Energy Laboratory at Northeast Agricultural University, combined with electrothermal heating. Experiments were conducted in an icing wind tunnel under controlled parameters: water flow rate (60 mL/min), ambient temperatures (−5 °C, −10 °C, −15 °C), incoming wind speeds (3 m/s, 6 m/s, 9 m/s), and energy flux densities (8 kW/m2, 10 kW/m2, 12 kW/m2). Results demonstrate that although higher wind speeds and lower temperatures increase de-icing energy demand, the hybrid coating-electrothermal approach significantly outperforms pure electrothermal de-icing across all tested scenarios: the highest energy-saving efficiency of 19.23 % was achieved at an energy flux density of 10 kW/m2; an energy reduction of 21.5 % was observed at an ambient temperature of −10 °C; and the optimal energy-saving effect was obtained at a wind speed of 6 m/s. This integrated strategy effectively reduces de-icing time by 25–68 s, lowers energy consumption by 12.89 % to 21.5 %, and significantly improves de-icing uniformity and thermal management stability. This study provides a practical solution and experimental basis for enhancing the energy efficiency and operational reliability of wind turbines in cold regions.
风力涡轮机叶片结冰严重影响涡轮机运行,而现有的独立防冰和除冰方法具有固有的局限性。本研究利用东北农业大学风能实验室自主研发的PCMS-C14相变微胶囊涂层,结合电热加热,对风力发电机叶片协同除冰性能进行了实验研究。实验在结冰风洞中进行,控制参数为:水流速度(60 mL/min)、环境温度(- 5℃、- 10℃、- 15℃)、来风速度(3 m/s、6 m/s、9 m/s)和能量通量密度(8 kW/m2、10 kW/m2、12 kW/m2)。结果表明,虽然较高的风速和较低的温度增加了除冰的能源需求,但在所有测试场景中,混合涂层-电热方法的节能效果明显优于纯电热除冰:在能量通量密度为10 kW/m2时,节能效率最高,达到19.23%;在环境温度为- 10℃时,能量降低21.5%;风速为6 m/s时,节能效果最佳。该综合策略可有效缩短除冰时间25 ~ 68 s,降低能耗12.89% ~ 21.5%,显著提高除冰均匀性和热管理稳定性。该研究为提高寒冷地区风力发电机组的能效和运行可靠性提供了切实可行的解决方案和实验依据。
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引用次数: 0
Mixing and entrainment of liquid fuel in a cavity-based scramjet model combustor 基于空腔的超燃冲压发动机模型燃烧室中液体燃料的混合与夹带
IF 3.3 2区 工程技术 Q2 ENGINEERING, MECHANICAL Pub Date : 2026-01-30 Epub Date: 2025-10-17 DOI: 10.1016/j.expthermflusci.2025.111629
Joel van der Lee, Weronika Senior-Tybora, Rudy Kaner, Yuval Aldema-Tshuva, Dan Michaels, Joseph K. Lefkowitz
This work quantitatively investigates liquid fuel mixing and entrainment in a cavity-based scramjet model combustor, focusing on potential and limitations of using an infrared imaging-based measurement technique. The proposed approach produces time-averaged path density maps that enable characterization of fuel distribution in a high-enthalpy supersonic crossflow. Using this method, a total of seven strut-assisted fueling strategies is systematically evaluated at a constant fuel mass flowrate. The discussion of measurement results addresses both the observed distribution maps and profiles, and their interpretation based on known physical processes of supersonic jet breakup, plume evolution, and crossflow interaction. The gained insights reveal key factors to fueling strategy design, such as jet penetration depth and orifice placement along the strut and injector location relative to the cavity. A series of combustion experiments were conducted to evaluate the flame holding characteristics of the injection strategies, allowing the mixing results, expressed in path-integrated fuel density, to be contextualized in terms of stabilization performance of the combustor. While path density is less intuitive, its proportionality between cases enables positioning within the stabilization envelope. In addition, the path density is a useful quantity for direct comparison to numerical modeling efforts. Together, these findings highlight the utility of infrared imaging to study mixing trends for guiding the design of advanced liquid fueling schemes in supersonic combustors.
本研究对基于空腔的超燃冲压发动机模型燃烧室中的液体燃料混合和夹带进行了定量研究,重点研究了基于红外成像的测量技术的潜力和局限性。所提出的方法产生了时间平均路径密度图,可以表征高焓超音速横流中的燃料分布。利用该方法,对恒定燃料质量流量下的7种支柱辅助加油策略进行了系统评价。对测量结果的讨论包括观测到的分布图和剖面,以及基于已知的超音速射流破裂、羽流演化和横流相互作用物理过程的解释。获得的见解揭示了加注策略设计的关键因素,例如射流穿透深度和沿支板的孔板位置以及相对于腔的注入器位置。进行了一系列燃烧实验来评估喷射策略的火焰保持特性,从而将混合结果(以路径集成燃料密度表示)与燃烧器的稳定性能联系起来。虽然路径密度不太直观,但其在情况之间的比例性使定位在稳定包络内。此外,路径密度是与数值模拟成果直接比较的有用量。总之,这些发现突出了红外成像在研究混合趋势以指导超音速燃烧室先进液体燃料方案设计中的应用。
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Experimental Thermal and Fluid Science
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