Experimental Thermal and Fluid Science最新文献

{"title":"Effects of heating orientation on flow boiling in copper manifold microchannel heat sinks","authors":"Huigang Wang ,&nbsp;Yue Qiu ,&nbsp;Jennifer Carter ,&nbsp;James McGuffin-Cawley ,&nbsp;Chirag R. Kharangate","doi":"10.1016/j.expthermflusci.2025.111553","DOIUrl":"10.1016/j.expthermflusci.2025.111553","url":null,"abstract":"<div><div>Recently, two-phase cooling configurations are being proposed to meet the power dissipation requirements of high heat flux electronic devices. Flow boiling in Manifold Microchannel (MMC) offers high heat transfer coefficients with low pressure drops, making it a popular choice. While many studies have explored flow boiling in microchannels, the influence of heating orientation in MMCs with complex 3D flow paths has not been investigated thoroughly. In this study, experiments are conducted to investigate the effects of heating orientations and mass flow rates on heat transfer performance, pressure drop, and the hysteresis phenomenon during flow boiling in a copper manifold microchannel heat sink, using the environmentally friendly refrigerant R1233zd(E) as the working fluid. Four heating orientations are studies: Upward Heating (UH), Downward Heating (DH), Horizontal Heating with Vertical Microchannels (HVMC), and Horizontal Heating with Vertical Manifolds (HVMF). The experiments are carried out with mass flow rates between 2.5 and 12.5 g/s, and the inlet subcooling temperature is set to 5 K. The results show that heating orientation significantly affects heat transfer performance, especially at high flow rates and higher heat fluxes. The Horizontal Heating with Vertical Manifolds (HVMF) configuration achieves the best heat transfer performance, while Downward Heating (DH) configuration exhibits the lowest performance. In contrast, heating orientation has a minimal effect on pressure drop performance. An increase in mass flow rate improves the heat transfer performance and raises the pressure drop in manifold microchannel heat sinks. Additionally, hysteresis phenomena are observed in both wall temperature and pressure drop between the heating and cooling curves. A notable wall temperature overshoot occurs before the Onset of Nucleate Boiling (ONB), which decreases with increasing mass flow rate. In the pressure drop curves, hysteresis is also evident, with higher pressure drops during the cooling process compared to the heating process at the same heat flux near ONB. The hysteresis in pressure drop becomes more pronounced at higher mass flow rates.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"169 ","pages":"Article 111553"},"PeriodicalIF":2.8,"publicationDate":"2025-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144471481","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":"Study on the effect of surfactant on the liquid diffusion process based on the liquid-core cylindrical lenses","authors":"Qing Yue ,&nbsp;Menghan Zou ,&nbsp;Zhiwei Li ,&nbsp;Licun Sun","doi":"10.1016/j.expthermflusci.2025.111550","DOIUrl":"10.1016/j.expthermflusci.2025.111550","url":null,"abstract":"<div><div>The liquid diffusion coefficient, reflecting the diffusion rate is an important basic parameter for studying the liquid mass transfer process. Speeding up liquid diffusion rates is of great significance for improving efficiency and reducing costs. However, at present, the commonly used methods mostly require increasing the temperature of the diffusion system, which is not usually applicable to active molecules. This paper proposes a new method to enhance the diffusion rate at room temperature by adding a small amount of an appropriate surfactant to a liquid diffusion system. To verify this method, the diffusion coefficients of ethylene glycol, glycerol, and triethylene glycol diffused in water with and without a surfactant (sodium dodecyl benzene sulfonate), at five different temperatures were accurately measured using the equal-refractive-index thin-layer method based on a liquid-core cylindrical lens. In addition, the diffusion activation energies of alcohols with and without surfactants were calculated using the Arrhenius formula. Results showed that the addition of a surfactant effectively reduced the diffusion activation energy and increased the liquid diffusion coefficient at room temperature. This method of enhancing the diffusion rate without temperature changes can be widely applied in the chemical, medicinal, and biological fields, among others.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"169 ","pages":"Article 111550"},"PeriodicalIF":2.8,"publicationDate":"2025-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144330389","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 investigation on the behavior and heat transfer of droplet impacting on heated surface","authors":"Weishi Peng ,&nbsp;Hanwen Luo ,&nbsp;Rongxuan Zhang ,&nbsp;Jinbiao Xiong","doi":"10.1016/j.expthermflusci.2025.111549","DOIUrl":"10.1016/j.expthermflusci.2025.111549","url":null,"abstract":"<div><div>Water droplet impact onto a heated hydrophilic sapphire, with surface temperature from 100 to 600 °C, was visualized with synchronized bottom- and side-view high-speed cameras. The liquid–solid contact modes are defined based on the morphology in the bottom-view images. Four types of dynamic contact patterns, i.e., <em>mottled</em>, <em>finger</em>, <em>ring</em> and <em>dot</em> contact patterns, are identified. Synthesizing the side- and bottom-view images, droplet impact behaviors are classified into four regimes: <em>deposition</em>, <em>rebound after contact</em>, <em>breakup after contact</em> and <em>Leidenfrost</em>. The ring contact pattern, appearing at <span><math><mrow><msub><mi>T</mi><mi>w</mi></msub></mrow></math></span>≈300°C, entraps generated vapor and results in upward jetting. The bottom-view images are processed and analyzed to quantify the liquid–solid contact area in each frame. Based on the solution of one-dimensional transient heat conduction within the contact area, heat transfer resulted from instantaneous liquid–solid contact was estimated. The total amount of heat transfer (Q) resulted from single droplet impact decreases with increasing surface temperature (<span><math><mrow><msub><mi>T</mi><mi>w</mi></msub></mrow></math></span>). However, on the Q-<span><math><mrow><msub><mi>T</mi><mi>w</mi></msub></mrow></math></span> curves the inflection points are observed near 300°C, implying heat transfer enhancement accompanied by upward jetting.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"169 ","pages":"Article 111549"},"PeriodicalIF":2.8,"publicationDate":"2025-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144330328","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 study on the icing hazards over the propeller of a Low-Altitude flight UAV under changeable liquid water content environment","authors":"Linchuan Tian ,&nbsp;Jingyi Tu ,&nbsp;Hong Liu ,&nbsp;Weiliang Kong ,&nbsp;Nianhong Han ,&nbsp;Wei Tian","doi":"10.1016/j.expthermflusci.2025.111546","DOIUrl":"10.1016/j.expthermflusci.2025.111546","url":null,"abstract":"<div><div>Low-altitude aerial operations frequently encounter rapidly varying ground meteorological conditions, leading to potential hazards for unmanned aerial vehicles (UAVs). To address this concern, a comprehensive experimental study was conducted to examine the icing hazards on UAV propellers, specifically in continuous and intermittent icing environments. The experiments were conducted in a specialized icing facility at Shanghai Jiao Tong University, designed to replicate flying conditions typical of UAVs, including continuous icing and intermittent precipitation scenarios. The findings reveal that, under identical durations of icing exposure, the intermittent icing environment resulted in more than 15% accumulation of ice mass on the propeller. This ice accretion led to a significant reduction in thrust coefficient, diminishing to less than 10% of its designed operational point, in contrast to a thrust coefficient of more than 16% observed under continuous icing conditions. Consequently, these results indicate that intermittent precipitation presents a greater hazard to UAV operations. Further analysis suggests that the disparity in heat transfer mechanisms, where the cold air and the propeller substrate have a prolonged interaction with the released latent heat, contributes to differing ice shape evolution patterns. This phenomenon resulted in a heightened local water collection rate during intermittent icing episodes, attributed to a reduced occurrence of ice and droplet shedding. As a consequence, there was a notable accumulation of larger ice formations at the leading-edge region of the propeller, with an increase of over 33% in the windward contact area across 95% of the spanwise distribution compared to baseline conditions. The presence of such icicles is expected to exacerbate local water collection rates, thereby leading to even more severe icing events for UAVs before the onset of ice shedding.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"169 ","pages":"Article 111546"},"PeriodicalIF":2.8,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144330388","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":"Asymmetric breakup of double emulsion droplets in symmetric junctions","authors":"Xiang Wang,&nbsp;Zhaomiao Liu,&nbsp;Yan Pang","doi":"10.1016/j.expthermflusci.2025.111542","DOIUrl":"10.1016/j.expthermflusci.2025.111542","url":null,"abstract":"<div><div>The transportation behaviors of double emulsion droplets in symmetric microfluidic junctions are investigated experimentally, with much attention paid to the particular behavior of the asymmetric breakup. The dynamic processes of interface evolution in typical flow patterns are captured. In contrast to previous studies, the dynamic analysis is carried out with different combinations of the inner and outer droplet lengths, based on which new flow pattern maps are built. The evolutions of the interfacial parameters including the extension length, minimum neck width, gap width, deformation factor, and profile asymmetry are given thorough discussions to reveal the transition rules between neighboring flow patterns. Based on the typical feature of the breakup process, geometric expressions of the maximum extension length is proposed to quantify the critical threshold of droplet breakup, which also helps explain the different influences of the varied bifurcation junctions. Two thread pinch-off regimes in the final stage are identified and the different characteristics in terms of the thread position and satellite droplet size are discussed. The fixed pinch-off position is confirmed to be the reason why droplets are more easily broken in the Y-junction, which also results in the nearly unchanged small asymmetry. For the T-junction, the lateral bias of the neck thread is found to reversely rely on the shift of the inner core owing to the influence between interfaces and the profile asymmetry increases with the length ratio of the inner to outer droplet length.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"169 ","pages":"Article 111542"},"PeriodicalIF":2.8,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144288812","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":"Natural convection experiments around an upper dome varying Rayleigh number and truncation angle","authors":"Su-Yeon Park,&nbsp;Dong-Hyuk Park,&nbsp;Bum-Jin Chung","doi":"10.1016/j.expthermflusci.2025.111548","DOIUrl":"10.1016/j.expthermflusci.2025.111548","url":null,"abstract":"<div><div>We carried out natural convection heat transfer experiments around upper domes varying truncation angles (<em>θ</em> = 90°, 70°, 50°, and 30°) over a wide range of Rayleigh number (<em>Ra_Db</em> = <em>gβ</em>Δ<em>TD_b</em>³/<em>αν</em>, 2.63 × 10⁹ ≤ <em>Ra_Db</em> ≤ 1.08 × 10¹³). The shape of a dome is close to the hemisphere as <em>θ</em> is 90° and to flat plate as <em>θ</em> is 0°. To achieve high <em>Ra_Db</em> condition, mass transfer experiments using H₂SO₄–CuSO₄ copper electroplating system were employed. Mass transfer rates were measured by electric current, and flows were observed by the Particle Image Velocimetry (PIV). The measured average Nusselt number (<em>Nu_Db</em> = <em>h_mD_b</em>/<em>k</em>) increased as <em>Ra_Db</em> increased and as the <em>θ</em> decreased. The enhancement was more significant at lower <em>Ra_Db</em> values, which is attributed to variations in the location of flow transition to turbulence and separation. At a relatively low <em>Ra_Db</em> (1.08 × 10¹⁰), flow remains attached but undergoes an early transition to turbulence when the <em>θ</em> is small. Meanwhile, when the <em>θ</em> becomes large, flow separation occurs without prior transition. As <em>Ra_Db</em> increases, however, flow separation occurs irrespective of the <em>θ</em>. <em>Nu_Db</em> of dome with <em>θ</em> = 30° had 35 % higher than the dome with <em>θ</em> = 90° at <em>Ra_Db =</em> 1.08 × 10¹⁰ until 18 % higher at <em>Ra_Db =</em> 1.08 × 10¹³. The <em>Nu_Db</em> correlation for an upper dome was developed. This work contributes not only to a deeper phenomenological understanding of natural convection heat transfer around upper domes but to the application to passive cooling of SMR outer containments.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"169 ","pages":"Article 111548"},"PeriodicalIF":2.8,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144288761","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":"First experimental investigation of high pressure methanol cavitating flow characteristics in quasi two-dimensional nozzles","authors":"Yizhou Yang ,&nbsp;Zhixia He ,&nbsp;Lian Duan ,&nbsp;Wei Huang ,&nbsp;Zhen Yang ,&nbsp;Ao Kang ,&nbsp;Genmiao Guo ,&nbsp;Wei Guan","doi":"10.1016/j.expthermflusci.2025.111547","DOIUrl":"10.1016/j.expthermflusci.2025.111547","url":null,"abstract":"<div><div>The global shift toward low-carbon solutions is driving the transition from fossil fuels to carbon-neutral fuels in engine applications. Methanol is gaining attention as a promising alternative due to its clean combustion and potential for reducing greenhouse gas emissions. High-pressure direct injection of methanol can reduce emissions and improve fuel efficiency, making it a viable solution for sustainable energy. However, the flow characteristics of methanol in injector nozzles are not well understood due to its unique physical properties compared to diesel and gasoline. The lack of experimental data limits precise control of injection rates and spray patterns. This study presents the first experimental analysis of high-pressure methanol flow in a quasi two-dimensional optical nozzle. An experimental platform was developed to control injection pressures from 1 to 10 MPa and back pressures from 0.1 to 4 MPa with ±1 % accuracy. Flow characteristics are studied under various pressures and temperatures, providing high-precision data for model validation. Comparative experiments were conducted to analyze the flow characteristics of methanol and diesel, providing insights for replacing diesel with methanol in engines. Results show that methanol has a higher discharge coefficient than diesel at higher cavitation numbers due to its lower viscosity, but a lower discharge coefficient at lower cavitation numbers due to stronger cavitation. Finally, a rounded-corner nozzle is introduced to reduce cavitation at the orifice entrance, confirming the role of back suction of the cavitation region in the exit shear layer in promoting the growth of the cavitation region inside the orifice.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"169 ","pages":"Article 111547"},"PeriodicalIF":2.8,"publicationDate":"2025-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144312476","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":"Blue emission in premixed hydrogen flames","authors":"Seunghyun Jo","doi":"10.1016/j.expthermflusci.2025.111545","DOIUrl":"10.1016/j.expthermflusci.2025.111545","url":null,"abstract":"<div><div>The origin of the blue emission in premixed hydrogen flames has been studied. Experiments examining the blue flame were performed using premixed hydrogen/air mixtures in an axisymmetric burner at a jet velocity of 12 m/s and varied equivalence ratios. Nitrogen was used to prevent the influence of a diffusion flame between the ambient air and the hydrogen flame. A spectrometer with a CCD camera measured emission spectra between 385 and 495 nm to identify species that affect the blue emission. Reaction rates, mole and mass fractions were calculated using Chemkin with the GRI 3.0 mechanisms. The blue flame is identified in visible pictures by its distinct emissions, which can be categorized into dark blue and light blue. Clear peaks have been identified in the wavelength range of 385–495 nm. The most pronounced peaks occur between 385 and 420 nm under fuel-lean and stoichiometric combustion conditions, while the peaks between 420 and 495 nm exhibit lower intensities. Emission intensities associated with hydroxyl radicals (OH) and atomic oxygen (O) demonstrate a strong correlation with the reaction rates of chemical reactions and their mole and mass fractions. Emission intensities linked to molecular hydrogen (H₂) and molecular oxygen (O₂) reveal a pronounced correlation with the reaction rates. Conversely, emissions related to atomic hydrogen (H) do not reveal a consistent relationship with their mole and mass fractions. The blue emission observed is likely influenced by a combination of OH, H₂, O₂, and O. The distinguishable peaks between 390 and 420 nm appear to result from the combined contributions of these species. The comparatively low peaks in the range of 440–495 nm are primarily associated with H₂. It is important to recognize that the blue emission in hydrogen flames could be affected by OH, H₂, O₂, and O.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"169 ","pages":"Article 111545"},"PeriodicalIF":2.8,"publicationDate":"2025-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144297701","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":"An analysis of the air intake process impacts on powdered fuel compression characteristics","authors":"Jiangang Yang ,&nbsp;Chunbo Hu ,&nbsp;Yijun Cao ,&nbsp;Wei Gao ,&nbsp;Xiangwen Zhang ,&nbsp;Kai Ma","doi":"10.1016/j.expthermflusci.2025.111544","DOIUrl":"10.1016/j.expthermflusci.2025.111544","url":null,"abstract":"<div><div>To clarify the influence of the tank intake process on the filling characteristics of powdered fuel in a powder ramjet, a method combining powder pneumatic compression experiments and theoretical analysis is employed to study the impact of intake flow rate, powdered fuel stacking height, and flow regulation process on the powdered fuel volume compression ratio (VCR). Based on the Ergun equation and the modified Kawakita equation, a calculation method for the VCR of powdered fuel during the intake process is proposed. The results indicate that the pressure drop between the upper and lower layers of powdered fuel during the intake process is the key factor leading to the volume compression of powdered fuel. Moreover, the VCR of powdered fuel is positively correlated with the intake flow rate and stacking height. The time when the powdered fuel reaches the maximum volume compression ratio (MVCR) is the same as the time when the change rate of gas pressure in the tank stabilizes. The MVCR of powdered fuel in the intake process is 20 %–45 % greater than that in the piston axial compression process. During the flow regulation process, the MVCR of powdered fuel is only related to the maximum intake flow rate and is independent of the regulation process.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"169 ","pages":"Article 111544"},"PeriodicalIF":2.8,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144262553","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":"Characterization of flame dynamics in a single-element lean direct injection combustion system","authors":"Mohamad M. Ghulam,&nbsp;Kranthi Yellugari,&nbsp;Shyam S. Muralidharan,&nbsp;Yuvi Nanda,&nbsp;Ephraim J. Gutmark","doi":"10.1016/j.expthermflusci.2025.111541","DOIUrl":"10.1016/j.expthermflusci.2025.111541","url":null,"abstract":"<div><div>This study explores how the equivalence ratio, inlet air temperature, confinement ratio, and exit boundary influence flame dynamics in a single-element, low-emission nozzle used in a lean direct injection combustion system. Using high-speed OH* chemiluminescence and sound pressure measurements, the research identifies three flame types—V-flame, M−flame, and lifted-distributed flame—with distinct behaviors. At higher equivalence ratios, the V-flame type shows axial fluctuation modes, in-phase coupling with the acoustic field, and higher sound intensity. This is highlighted by the near match in frequency between flame mode (830 Hz) and sound pressure (822.6 Hz), suggesting flame-acoustic interaction. In contrast, the M−flame, found at lower equivalence ratios, exhibits radial fluctuation modes, out-of-phase acoustic decoupling, and lower sound intensity. Sound intensity shows a linear correlation with equivalence ratio; as lean blowout (LBO) nears, the flame structure becomes incoherent, and turbulence dominates external noise. Increasing the inlet temperature or adding an exit plate shifts the flame anchoring point upstream. Higher inlet temperatures lower air density, raising axial velocity and shrinking inner recirculation zones, promoting a V-flame near the nozzle exit. Similarly, adding an exit plate increases the pressure gradient in reverse flow regions, pushing the flame upstream. Inlet temperature amplifies axial fluctuation modes, while the exit plate enhances an axial-radial fluctuation mode. Larger confinement ratios, such as 6.9 and 9.6, enlarge the inner recirculation zone and favor radial fluctuation modes, with sound pressure levels shifting by up to 15 dB during flame structure transitions. These parameters influence the LBO limit, critical for NOx emissions.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"169 ","pages":"Article 111541"},"PeriodicalIF":2.8,"publicationDate":"2025-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144239610","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}