Experimental Thermal and Fluid Science最新文献

{"title":"Spreading characteristics of water droplets impacting onto a moving hydrophilic surface","authors":"Zhibing Zhu ,&nbsp;Jinzu Yang ,&nbsp;Shuai Yang ,&nbsp;Xiaojing Sun ,&nbsp;Xuan Zhang","doi":"10.1016/j.expthermflusci.2025.111449","DOIUrl":"10.1016/j.expthermflusci.2025.111449","url":null,"abstract":"<div><div>The impingement of water droplets onto solid moving surfaces is a ubiquitous phenomenon in nature and industry, making it fundamentally important to understand the droplet spreading dynamics. Here, the influence of surface movement on the asymmetric spreading characteristics of water droplets on horizontally moving hydrophilic surfaces is experimentally investigated. The spreading process and liquid film morphology, maximum spreading factor and time, and liquid film centroid are analyzed under different tangential moving and normal impact Weber numbers (i.e., <em>We</em>_t and <em>We</em>_n). In the moving direction, the spreading is stretched by the surface movement, increasing the maximum spreading diameter. Ellipse and tail patterns are observed in the regions of <em>We</em>_t &lt; 0.72<em>We</em>_n and <em>We</em>_t &gt; 0.72<em>We</em>_n. For both patterns, the ratios of the maximum spreading factor in the moving direction to that perpendicular to the moving direction could be expressed as functions of <span><math><mrow><mi>W</mi><msubsup><mi>e</mi><mrow><mtext>t</mtext></mrow><mrow><mn>0.5</mn></mrow></msubsup><mi>W</mi><msubsup><mi>e</mi><mrow><mtext>n</mtext></mrow><mrow><mo>-</mo><mn>0.5</mn></mrow></msubsup></mrow></math></span>. The spreading time perpendicular to the moving direction is reduced by the surface movement and this reduction is normalized by a modified correlation. The liquid film centroid travels slower than the moving surface in the early stage and travels as fast as the moving surface in the final stage. The relative displacement of the liquid film centroid can be scaled as <span><math><mrow><mi>W</mi><msubsup><mi>e</mi><mrow><mtext>t</mtext></mrow><mrow><mn>0.5</mn></mrow></msubsup><mi>W</mi><msubsup><mi>e</mi><mrow><mtext>n</mtext></mrow><mrow><mo>-</mo><mn>0.5</mn></mrow></msubsup></mrow></math></span>. This study deepens our understanding of the droplet impact behaviors on moving surfaces and the findings help analyze the dynamics on more compilated moving surfaces.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"165 ","pages":"Article 111449"},"PeriodicalIF":2.8,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143471213","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":"The response of a turbulent boundary layer to a sudden ridge-type roughness array with a sinusoidal pattern","authors":"Francesco Scarano ,&nbsp;Tomek Jaroslawski ,&nbsp;Erwin R. Gowree","doi":"10.1016/j.expthermflusci.2025.111444","DOIUrl":"10.1016/j.expthermflusci.2025.111444","url":null,"abstract":"<div><div>An experimental investigation was conducted to analyze the impact of a sinusoidal ridge-type roughness patch on the response of a moderate Reynolds number turbulent boundary layer (friction Reynolds number <span><math><mrow><mi>R</mi><msub><mrow><mi>e</mi></mrow><mrow><mi>τ</mi></mrow></msub><mo>&lt;</mo><mn>1100</mn></mrow></math></span>). A streamwise sinusoidal pattern with an amplitude denoted as <span><math><mi>A</mi></math></span> and a wavelength <span><math><mi>Λ</mi></math></span> was imposed on the ridges while maintaining fixed the spanwise spacing between the ridges, <span><math><mi>S</mi></math></span>, smaller than the boundary layer thickness, <span><math><msub><mrow><mi>δ</mi></mrow><mrow><mo>.</mo><mn>99</mn></mrow></msub></math></span> (<span><math><mrow><mi>S</mi><mo>/</mo><msub><mrow><mi>δ</mi></mrow><mrow><mo>.</mo><mn>99</mn></mrow></msub><mo>&lt;</mo><mn>1</mn></mrow></math></span>). Two sinusoidal ridges are tested plus the standard straight configuration; the wavelengths being <span><math><mrow><mn>2</mn><mo>.</mo><mn>6</mn><msub><mrow><mi>δ</mi></mrow><mrow><mo>.</mo><mn>99</mn></mrow></msub></mrow></math></span> and <span><math><mrow><mn>1</mn><mo>.</mo><mn>3</mn><msub><mrow><mi>δ</mi></mrow><mrow><mo>.</mo><mn>99</mn></mrow></msub></mrow></math></span>. Oil droplet interferometric measurement conducted downstream the ridges, in the recessed part, revealed a local reduction in skin friction for the sinusoidal ridged configurations. Hot-wire anemometry was employed to measure the boundary layer on the smooth wall downstream of the roughness array. The measurements revealed a modification of the mean velocity profile and an increase in the shape factor. Significant modifications in spectral content between configurations with aligned and sinusoidal ridge-type roughness are shown. The presence of ridges caused a noticeable upward shift of energy and the emergence of an outer peak in the contour of the premultiplied energy spectrogram. The outer peak is located at a wall normal distance in wall units between 80 and 180 depending on the Reynolds number. Interestingly, configurations with sinusoidal patterns exhibited a more pronounced upward shift of energy in the premultiplied spectra. The energy associated with the outer peak for the configuration having shorter wavelength is doubled compared with standard straight ridges. These findings suggest that the response of the turbulent boundary layer is influenced not solely by the spanwise spacing of ridges but also by the waviness of the ridges, which further contributes to its intensification.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"165 ","pages":"Article 111444"},"PeriodicalIF":2.8,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143508821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental investigation on the influence of surface conditions on boiling heat transfer during quenching of a cylinder in subcooled water","authors":"Yang Liu ,&nbsp;Ping Xiong ,&nbsp;Qiushi Li ,&nbsp;Tao Lu ,&nbsp;Qifeng Jiang ,&nbsp;Yan Luo ,&nbsp;Linglan Zhou ,&nbsp;Shihao Yang","doi":"10.1016/j.expthermflusci.2025.111446","DOIUrl":"10.1016/j.expthermflusci.2025.111446","url":null,"abstract":"<div><div>In this study, comparative experiments were conducted on the quenching boiling in distilled water of SS, FeCrAl and Zr-4 cylinders to investigate their flow and heat transfer performance. The high-speed camera was used to visualize the transient quenching boiling behavior. By employing the validated inverse heat conduction problem (IHCP) method, the surface temperature and heat flux were obtained based on measured temperature inside the cylinder. The experiment results indicate that within the increase of coolant subcooling degree, surface roughness, and decrease of the product of the thermophysical properties of solid materials (<em>ρkc_p</em>), the duration of quenching boiling decreases, the minimum film boiling temperature (<em>T_min</em>) increases, and the heat transfer performance is enhanced. Moreover, the influence of coolant subcooling degree on quenching boiling process is more pronounced than that of surface roughness. The micron-scale microstructure of the rough surface has a minimal effect on the heat transfer of the vapor film, but it triggers the early collapse of the vapor film and raises <em>T_min</em>. It is noteworthy that under the lower subcooling condition of 5℃ in the experiment, there are notable differences in the types of vapor film collapse between the rough surface and smooth surface, namely Coherent Collapse and Propagative Collapse. Compared with SS and FeCrAl, the quenching heat transfer of Zr-4 is more susceptible to surface oxidation. Furthermore, a new correlation for <em>T_min</em> is developed, that couples the influence of the surface roughness, coolant subcooling degree, and solid thermophysical properties, with most predicted values falling within a 10% margin of error.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"165 ","pages":"Article 111446"},"PeriodicalIF":2.8,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143526994","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":"Thermal conductivity of carboxymethyl cellulose-based Fe3O4 and Al2O3 nanofluids: An improved measurement method","authors":"Shengna Liu ,&nbsp;Xuehui Chen ,&nbsp;Kheder Suleiman ,&nbsp;Erhui Wang","doi":"10.1016/j.expthermflusci.2025.111431","DOIUrl":"10.1016/j.expthermflusci.2025.111431","url":null,"abstract":"<div><div>In this study, the rheological coupling thermal conductivity (TC) measurement method was improved using two approaches. And this improved measurement was applied to study the thermal conductivities (TCs) of self-made carboxymethyl cellulose (CMC) based Fe₃O₄ and Al₂O₃ nanofluids (NFs). The results show that, the improved TC measurement method more accurately assesses the contribution of viscous dissipative heat (VDH) to TC, thereby significantly enhancing the precision of the measurement outcomes. For these two NFs, an interlinked effect is observed: an increase in either volume fraction or shear rate leads to a more pronounced enhancement of TC, with each factor amplifying the other’s influence. The maximum contribution of VDH to TC is 17.11% for Fe₃O₄ NF and 12.21% for Al₂O₃ NF, highlighting the significance of VDH in high-viscosity fluid flows. Based on the experimental data, a constitutive model for the TC dependence on shear rate and volume fraction was proposed. Rheological constitutive model of the two NFs is the Carreau model, and the parameters of the Carreau model are all quadratic polynomials of the nanoparticle volume fraction.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"164 ","pages":"Article 111431"},"PeriodicalIF":2.8,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143422338","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":"Design and validation of an air-bearing-based micro skin-friction balance for small area samples","authors":"Wenyuan Zhou ,&nbsp;Xiangdong Liu ,&nbsp;Yinglu Sun ,&nbsp;Xianglian Lyu ,&nbsp;Yang He ,&nbsp;Weizheng Yuan","doi":"10.1016/j.expthermflusci.2025.111433","DOIUrl":"10.1016/j.expthermflusci.2025.111433","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Skin friction, or wall shear stress is a fundamental parameter for characterizing turbulent boundary layer (TBL). Among various methods, the floating element (FE) method has long been advocated and developed. However, accurately measuring WSS for small-area samples remains challenging. This paper proposes air-bearing-based high-resolution micro skin-friction balance and a corresponding sliding-covering measurement method. As an extension of the traditional flush-mounted FE measurement method, it reduces errors caused by the edge gap and gap flow of the floating elements, and employs a clamping mechanism for high-precision assembly, thereby enhancing the measurement efficiency and accuracy for small-area samples. The error sources in balance calibration and measurement were carefully analyzed, with corresponding uncertainty calculated. The measurement range and resolution are &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;12&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;N&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;5&lt;/mn&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;7&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;N&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, respectively. For a smooth surface, assume the measured force is &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;4&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;N&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, and the measurement precision is approximately &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;047&lt;/mn&gt;&lt;mtext&gt;%&lt;/mtext&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. The balance is validated using a smooth-wall zero-pressure-gradient TBL. The measured skin-friction coefficient, &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;C&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;≡&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mover&gt;&lt;mrow&gt;&lt;mi&gt;τ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;̄&lt;/mo&gt;&lt;/mrow&gt;&lt;/mover&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;w&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;q&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;∞&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, generally follows a Coles–Fernholz relation &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;C&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mfenced&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;κ&lt;/mi&gt;&lt;mo&gt;ln&lt;/mo&gt;&lt;mfenced&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Re&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;θ&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/mfenced&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mi&gt;C&lt;/mi&gt;&lt;/mrow&gt;&lt;/mfenced&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; within &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;mtext&gt;%&lt;/mtext&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; (with chosen constant of &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;κ&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;384&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;C&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;4&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;12&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;) for a momentum-thickness-based Reynolds number &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Re&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;θ&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;1050&lt;/mn&gt;&lt;mo&gt;∼&lt;/mo&gt;&lt;mn&gt;3361&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. Additionally, the skin friction on the surfaces of two envelope materials (EMs) used for airships was measured using the sliding-covering method. ","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"164 ","pages":"Article 111433"},"PeriodicalIF":2.8,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143422340","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":"Evaluation of high-speed laser triangulation and LIDAR for turbulent water surface ranging","authors":"Jure Zevnik ,&nbsp;Marko Hočevar ,&nbsp;Sabina Kolbl-Repinc ,&nbsp;Gašper Rak","doi":"10.1016/j.expthermflusci.2025.111432","DOIUrl":"10.1016/j.expthermflusci.2025.111432","url":null,"abstract":"<div><div>This study presents a comparison of high-speed laser triangulation and laser scanning, two advanced measurement methods for capturing the free water surface of complex hydraulic phenomena characterized by turbulent, non-stationary, and non-homogeneous flows. The methods were applied to measure the turbulent, aerated water surface of a flow under supercritical flow conditions, defined by high Reynolds and Froude numbers. Measurements were conducted using a high-speed camera operating on the principle of laser triangulation, and a laser scanner serving as a light source. Data evaluation was performed for three cross-sections along the confluence, indicating a very good overall agreement between both measuring systems with mean discrepancies of 0.26 mm horizontally and 2.7 mm vertically, which fall within the reported systematic and statistical errors of the light detection and ranging (LIDAR) device. With most relative errors within ±10 %, the mean differences between the two measurement systems were an order of magnitude smaller than the temporal and spatial fluctuations of the observed free surfaces, and the instantaneous errors remained within the physical range of these fluctuations. Further error analysis revealed that high-speed triangulation underestimates free surface levels in flows with steadier, well-defined water surfaces, and overestimates in regions with highly transient and poorly defined surfaces compared to LIDAR. These discrepancies were attributed to differing system sensitivities. The high-speed camera sensor exhibits higher sensitivity, capturing more reflections from water droplets and successive reflections from submerged air bubbles compared to the LIDAR device. This highlights the need for further investigation into these error sources and the development of more robust data filtering techniques. Overall, both methods effectively captured the complex dynamics of turbulent aerated flows, showing promising capabilities for measuring turbulent water surfaces in laboratory environments.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"164 ","pages":"Article 111432"},"PeriodicalIF":2.8,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental study and correlation analysis of breakup characteristics of liquid nitrogen jets","authors":"Yanling Yang ,&nbsp;Kang Cen ,&nbsp;Mengxin Li ,&nbsp;Chunlan Zhao ,&nbsp;Yixi Wang ,&nbsp;Wei Lie ,&nbsp;Yuan Wei ,&nbsp;Qiang Yuan","doi":"10.1016/j.expthermflusci.2025.111443","DOIUrl":"10.1016/j.expthermflusci.2025.111443","url":null,"abstract":"<div><div>Liquid nitrogen (LN₂) has garnered increasing attention due to its potential applications in various fields. When the LN₂ jet is accidentally released into an environment with a lower saturation pressure, it may lead to significant hazards due to the formation of a two-phase flow. In this study, a cryogenic experimental system with adjustable temperature and pressure was developed to investigate the two-phase flow behavior of LN₂ jets. The influencing factors affecting jet characteristics are quantified by Buckingham theorem. Through multiple regression analysis, the key feature parameters affecting the jet morphological transition are identified, and the transition criteria of different breakup regimes were developed. The results show that the transition criteria can accurately predict the morphological transitions from mechanical breakup to partially flashing and partially flashing to fully flashing, and the maximum error between the predicted results and the experimental data are within ±5 % and ±15 %, respectively. The key feature parameters affecting the discharge coefficient are identified by decision tree model, and the correlation of discharge coefficient in different breakup regimes is proposed by multivariate linear fitting method. The results show that discharge coefficient correlation has good predictive performance, and its maximum errors are within ±9.5 %, ± 5 % and ±15 %, respectively.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"164 ","pages":"Article 111443"},"PeriodicalIF":2.8,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143422337","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 of two and three-phase steady flows in inclined rising pipes","authors":"António Freire Diogo,&nbsp;Pedro Maio Moura","doi":"10.1016/j.expthermflusci.2025.111430","DOIUrl":"10.1016/j.expthermflusci.2025.111430","url":null,"abstract":"<div><div>This paper presents, interrelates, and discusses the main experimental results that have been obtained in three experimental campaigns performed in the Laboratory of Hydraulics, Water Resources and Environment (LHWRE) of Coimbra University in three different configurations of an installation that was built and developed for the study of steady multiphase flows in inclined rising pipes. The first and second configurations, working in pipe steady flow, were prepared to allow original measurements and innovative studies about the liquid flow rate increase, keeping the total head at an upstream inlet chamber of a subsystem initially ruled by gravity, and the gain of total head at the chamber, for given initial liquid flow rates, both due to the air-lift effect caused by gas–liquid two-phase flows in two inclined rising conduits of 35 mm transparent plasticized PVC and of 94.5 mm LDPE. The third configuration was prepared to allow original and innovative measurements and studies about the solids transport in liquid–solids two-phase flows and gas–liquid–solids three-phase flows, both accomplished in an inclined rising 84 mm transparent acrylic pipe, simulating both steady turbulent flows initially governed by gravity and forced in conventional pumping systems. The results of the experiments performed with air, water, sand and fine gravel, with air flow rates between about 0.5 and 4.5 L/s, water flow rates up to about 9 L/s and granular material between 0.425 mm and 7.20 mm show that the presence of a gas phase in steady upward multiphase flows in an inclined pipe improves expressively both the flow performance of the liquid phase and the solids transport, avoiding, in particular, the sedimentation of solid particles. In large municipal or intermunicipal wastewater systems, the gas phase may be the air or oxygen required for sulfide control, which may be injected in steady flow in the base of the rising pipes. The installation may be adapted to transport other fluids, like hydrocarbons, muds from mining or dredging works, for example, or sludge from wastewater treatment plants, developing and expanding the main basic conclusions obtained to a relevant and wide field of several practical applications.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"165 ","pages":"Article 111430"},"PeriodicalIF":2.8,"publicationDate":"2025-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143445105","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":"Fringe tracking analysis in background oriented Schlieren for strongly refracting fluids","authors":"Tao Xu ,&nbsp;Xu Chen ,&nbsp;Jing Meng","doi":"10.1016/j.expthermflusci.2025.111434","DOIUrl":"10.1016/j.expthermflusci.2025.111434","url":null,"abstract":"<div><div>Background oriented Schlieren (BOS) is a quantitative method for measuring the density distribution of fluid fields. The current commonly used methods such as cross-correlation and Fourier transform encounter challenges when measuring fluids with strong refraction, manifesting as the indistinct distortion of the background patterns. This issue is caused by the rapid changes in density gradients associated with the pattern displacement. To address this problem, we develop the fringe tracking analysis method for BOS based on periodic fringe patterns. We establish a quantitative theoretical relationship between the fringe shape and the density distribution by tracking each complete fringe in the background pattern and calculating their deformation. This method is applied in the laboratory to measure the density of stable and dynamic fields with internal waves. Comparisons with conductivity probe measurements and internal wave theory confirm the method’s accuracy in measuring fluids with large displacement gradients. By establishing an imaging numerical simulation, the performance and limitations of this method in image processing are evaluated. The results show that this method achieves an accuracy exceeding 5% within its effective range for measuring density fields and exhibits robustness against noise. Finally, we provide guidelines for designing fringes in measuring different density fields. This work presents an effective method for measuring density variations in fluids with large refractive index, such as strong stratified fluids, as well as burning and shock waves.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"164 ","pages":"Article 111434"},"PeriodicalIF":2.8,"publicationDate":"2025-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143387126","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":"Effect of carrier concentration on rheological behavior of high density PCM slurry","authors":"Hikaru Ebihara ,&nbsp;Shunsuke Abe ,&nbsp;Tatsunori Asaoka","doi":"10.1016/j.expthermflusci.2025.111429","DOIUrl":"10.1016/j.expthermflusci.2025.111429","url":null,"abstract":"<div><div>Erythritol slurry has demonstrated significant potential as a heat transfer medium. This study focused on the changes in the density difference between dispersed particles and the carrier fluid by varying the carrier fluid concentration within the range of 45–65 mass%. To estimate the density difference, the density of the carrier fluid, an erythritol aqueous solution, was measured at various temperatures and concentrations using a hydrometer. The pressure drop of erythritol slurry was measured in horizontal homogeneous flow. The results indicate that the non-Newtonian characteristics become more pronounced as the carrier concentration decreases, particularly under high solid fraction conditions. Moreover, the particle Reynolds number was proposed as a key parameter for evaluating the non-Newtonian characteristics of erythritol slurry. A correlation was developed between the power-law index <em>n′</em>, solid fraction, and particle Reynolds number. The calculated values showed good agreement with the experimental values of <em>n’</em>, with nearly all values within ± 10 % for solid fractions of 0–14 vol% and particle Reynolds numbers of 0.8–2.0.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"164 ","pages":"Article 111429"},"PeriodicalIF":2.8,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143379385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}