Experimental Thermal and Fluid Science最新文献

{"title":"The spraying characteristics of electrohydrodynamic atomization under different nozzle heights and diameters","authors":"Yin Guan ,&nbsp;Yanxiu Sha ,&nbsp;Hao Wu ,&nbsp;Jingze Zheng ,&nbsp;Bin He ,&nbsp;Yang Liu ,&nbsp;Yihang Lei ,&nbsp;YongAn Huang","doi":"10.1016/j.expthermflusci.2025.111551","DOIUrl":"10.1016/j.expthermflusci.2025.111551","url":null,"abstract":"<div><div>Electrohydrodynamic atomization (EHDA), the atomization mode of variable electrohydrodynamic (EHD) spraying process, has been extensively studied and widely applied in assorted micro/nanoscopic engineering applications in recent years. However, many aspects of the rapidly changing liquid atomization behavior are not fully understood, especially that the impacts of nozzle height and diameter on the spraying characteristics of EHDA are quite lacking in the literature. In view of this, we performed an experimental work on EHDA under four most fundamental operating parameters including electric voltage, liquid flow rate, nozzle height, and nozzle diameter. Eight distinct spraying modes, namely Spindle, Pulsating Jet, Rotating Atomization, Pulsating Atomization, Stable Atomization, Tilted Atomization, Oscillating Jet, and Multi-jet were observed. The variations of spraying mode, Taylor cone length and angle, liquid jet breakup length, liquid jet rotating and pulsating frequency, atomization angle, and atomization area are analyzed in terms of electric Bond number and dimensionless flow rate, which are two most frequently used dimensionless variables in EHD spraying studies. Meanwhile, the influences of nozzle height and diameter on liquid spraying characteristics are also discussed. The Rotating Atomization and Pulsating Atomization modes are two newly discovered spraying modes that have not been reported in previous EHDA articles. The spraying characteristics of these two modes are examined in detail, which are also compared with those of the Stable Atomization mode obtained in this work, for the purpose of exploring their potential applications in the future.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"169 ","pages":"Article 111551"},"PeriodicalIF":2.8,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144501086","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":"Heat transfer augmentation using collapsible tube-induced pulsating flow","authors":"Aashish Ranjan,&nbsp;P. Deepu,&nbsp;Subrata Kumar","doi":"10.1016/j.expthermflusci.2025.111543","DOIUrl":"10.1016/j.expthermflusci.2025.111543","url":null,"abstract":"<div><div>This study investigates the enhancement of heat transfer rates using a simple passive pulsation mechanism facilitated by a collapsible tube (CT). A comparative analysis between the collapsible tube and a rigid tube is conducted at various Reynolds numbers (<span><math><mrow><mi>R</mi><mi>e</mi></mrow></math></span>) to understand the impact of pulsation on the thermal and flow characteristics. The results show that the CT-induced pulsation significantly enhances the heat transfer rate, with an observed increase ranging from 70% to 50% at lower <span><math><mrow><mi>R</mi><mi>e</mi></mrow></math></span> (581 to 1597) with a corresponding Strouhal number (<span><math><mrow><mi>S</mi><mi>r</mi><mo>⪆</mo><mn>0</mn><mo>.</mo><mn>2</mn></mrow></math></span>). However, the enhancement diminishes at higher <span><math><mrow><mi>R</mi><mi>e</mi></mrow></math></span> beyond 1597, characterized by a lower pulsation frequency (<span><math><mrow><mi>S</mi><mi>r</mi><mo>⪅</mo><mn>0</mn><mo>.</mo><mn>15</mn></mrow></math></span>), reducing from 44% at <span><math><mrow><mi>R</mi><mi>e</mi></mrow></math></span> = 1742 to 23% at <span><math><mrow><mi>R</mi><mi>e</mi></mrow></math></span> = 2323, as compared to the rigid tube case. Additionally, the thermohydraulic performance index (TPI) is assessed to quantify the efficiency of heat transfer rate relative to pressure losses in the collapsible tube system. Proper Orthogonal Decomposition (POD) analysis is employed to extract key flow structures and characterize the pulsation dynamics. The POD results reveal that the dynamic behaviour of the collapsible tube introduces energetic intermittent coherent structures in the flow field, which are absent in the rigid tube case, contributing to enhanced mixing and more efficient heat transfer. These findings suggest that employing a collapsible tube offers a practical strategy for significantly improving the heat transfer rate in various engineering applications without the need for complex active control systems.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"169 ","pages":"Article 111543"},"PeriodicalIF":2.8,"publicationDate":"2025-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144471479","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":"Impact of electrode surface texturing on hydrogen bubble dynamics during proton exchange membrane water electrolysis","authors":"Jakob Raeymaekers ,&nbsp;Klara Arhar ,&nbsp;Matic Može ,&nbsp;Pierre Colinet ,&nbsp;Iztok Golobič ,&nbsp;Johan Steelant ,&nbsp;Maria Rosaria Vetrano","doi":"10.1016/j.expthermflusci.2025.111538","DOIUrl":"10.1016/j.expthermflusci.2025.111538","url":null,"abstract":"<div><div>Water electrolysis systems are vital for sustaining human life during long-term space exploration missions. The main obstacle to the in-space operation of a water electrolysis system is the near-absence of buoyancy forces, impeding the detachment of hydrogen and oxygen bubbles from the electrodes and further complicating gas management, a crucial factor for efficient operation even in terrestrial applications. One of the most promising approaches to mitigate this problem is the micro- or nanostructuring of the electrode surfaces. Via surface structuring, the electrochemically active surface area can be enlarged and hydrophilicity increased, leading to easier detachment of gas bubbles. Additionally, bubble nucleation can be improved and bubble coalescence reduced. In this study, five pairs of laser-textured electrodes are manufactured, characterized and analyzed in terms of their performance and their influence on the bubble dynamics of the produced hydrogen gas. All textured electrodes achieve a performance enhancement over the unmodified surface (10% to 45% increase in current density for the same supply voltage). Gas production experiments prove that an increase in current density at a given voltage directly corresponds to a rise in production rate and, hence, in electrolysis performance. Significant differences in the bubble size distribution are observed on the different surfaces, as well as at different supply voltages. Distribution shapes and parameters (mean and standard deviation) remain mostly constant over time. Bubble rise velocities are significantly influenced by the entrainment of flow by the rising bubble plumes. Bubble growth after detachment is proven to be diffusion-controlled, and mainly determined by the degree of supersaturation close to the electrodes. This study proves that modification of the electrode surface morphology influences the performance of PEM systems by alteration of the bubble behavior during operation.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"169 ","pages":"Article 111538"},"PeriodicalIF":2.8,"publicationDate":"2025-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144471480","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":"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}