Experimental Thermal and Fluid Science最新文献

{"title":"Experimental investigation of lean blow-out on bluff-body stabilized flames using simultaneous OH/kerosene-PLIF measurements in partially vapourised kerosene","authors":"Guohua Wu ,&nbsp;Xin Yu ,&nbsp;Jiangbo Peng ,&nbsp;Chaobo Yang ,&nbsp;Bin Hu ,&nbsp;Zhen Cao ,&nbsp;Yingjie Song","doi":"10.1016/j.expthermflusci.2025.111458","DOIUrl":"10.1016/j.expthermflusci.2025.111458","url":null,"abstract":"<div><div>Experimental investigation of the lean blow-out (LBO) on bluff-body stabilized flames in partially vapourised kerosene was conducted using simultaneous hydroxyl (OH)/kerosene- planar laser-induced fluorescence (PLIF) measurement technique. By comparing with kerosene-PLIF, interference fluorescence in OH-PLIF was eliminated. The results indicated that as the LBO was approached, the OH-PLIF region gradually decreased, and the flame transitioned from cylindrical to conical shape. Beyond Z=1.5D, the intensity of kerosene-PLIF gradually decreased. Furthermore, as the LBO was approached, the flame surface moved towards the recirculation zone (RZ), and the flame surface density (FSD) gradually decreased, indicating the significant role of RZ in the LBO process. Lastly, this study employs simultaneous kerosene-PLIF and OH-PLIF data for Simultaneous Dynamic Decomposition (SDD) analysis to extract the dominant frequencies and their corresponding spatial structures. The results indicate that as the LBO was approached, the dominant frequency of SDD gradually decreases. The spatial structure of kerosene-PLIF exhibits an alternating distribution of positive and negative oscillation intensities, while the spatial structure of OH-PLIF signals progressively concentrate in the RZ.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"166 ","pages":"Article 111458"},"PeriodicalIF":2.8,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143577566","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 effects of turbulence intensity on the aeroelastic stability of wind turbine airfoils","authors":"Yaya Jia ,&nbsp;Jiahao Lu ,&nbsp;Zonghan Zhao ,&nbsp;Qingkuan Liu ,&nbsp;Shanning Lv","doi":"10.1016/j.expthermflusci.2025.111457","DOIUrl":"10.1016/j.expthermflusci.2025.111457","url":null,"abstract":"<div><div>The trend toward larger wind turbines also makes the aeroelastic stability of ultra-long flexible blades more sensitive to environmental excitations such as turbulence intensity. Using a specialized airfoil designed for large wind turbines as the research subject, synchronized wind tunnel tests of vibration and pressure were performed to systematically study the effects of turbulence intensity on the aeroelastic stability of the airfoil and to explore its underlying mechanisms. The results showed that different values of incoming turbulence intensity had opposite effects on the aeroelastic response of the airfoil. Accordingly, the environment with different turbulence intensities was divided into zones: turbulence-promoting vibration zone, transition zone, and turbulence-suppressing vibration zone. In the turbulence-promoting vibration zone, the appearance from the leading-edge vortex triggered stall flutter in the airfoil, and the stall flutter was restricted to the specific wind speed scope. As the turbulence intensity increased, the wind speed scope for stall flutter advanced and expanded. In the transition zone, the airfoil’s torsional vibration characteristics became extremely complex, and four types of aeroelastic responses were observed: small amplitude random aeroelastic response, stall flutter, special dual-frequency vibration, and buffeting caused by turbulence excitation. In the turbulence-suppressing vibration zone, high turbulence intensity significantly suppressed the separation of the boundary layer at the airfoil’s suction surface, while only two types of aeroelastic responses were observed, corresponding to the first small amplitude random aeroelastic response and the fourth buffeting caused by turbulence excitation in the transition zone, with the amplitude of buffeting significantly smaller than that in the transition zone.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"166 ","pages":"Article 111457"},"PeriodicalIF":2.8,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143577567","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":"Collision and spreading behavior of rapid tin droplets on stainless-steel substrate surfaces under ultrasonic vibration","authors":"Xiwushan Wang ,&nbsp;Weiyuan Yu ,&nbsp;Baoqing Yang ,&nbsp;Shirong Zhu ,&nbsp;Fengfeng Wang ,&nbsp;Mingkang Wang","doi":"10.1016/j.expthermflusci.2025.111447","DOIUrl":"10.1016/j.expthermflusci.2025.111447","url":null,"abstract":"<div><div>Applying ultrasonic vibration in a novel droplet-based additive manufacturing method holds significant promise. This is attributed to the ability of ultrasonic vibration to alter the dynamic dynamics of droplets spreading on the underlying substrate, enhancing wetting. Our study focuses on the dynamic properties and wettability of tin droplets on a stainless-steel surface under ultrasonic vibration. We investigate changes in spreading diameter, wetting angles, and post-solidification macroscopic morphology. Findings demonstrate that ultrasonic vibration considerably promotes droplet spreading, reducing retraction, especially at higher material temperatures. During expansion, dynamic wetting angle oscillations occur. Post-solidification, the tin droplet surface exhibits a more consistent ripple pattern. At lower temperatures, ultrasonic wave-induced wettability enhancement is minimal, but at higher temperatures, it significantly boosts substrate wetting by tin droplets. This enhancement is attributed to ultrasonic vibration’s influence on droplet kinetic, surface, and adhesion energy, notably above the tin droplets’ melting point. Ultrasonic vibration, providing up to 60% of the initial energy, significantly aids droplet wetting and spreading. Our study elucidates the importance of ultrasonic waves in high-speed droplet processes, offering theoretical guidance for ultrasound-assisted droplet deposition methods.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"165 ","pages":"Article 111447"},"PeriodicalIF":2.8,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143512704","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":"Corrigendum to “Flow characteristics of dispersed two-phase flows in an 8 × 8 rod bundle” [Exp. Therm. Fluid Sci. 153 (2024), 111146]","authors":"Meng Yu ,&nbsp;Takashi Hibiki ,&nbsp;Naofumi Tsukamoto ,&nbsp;Shuichiro Miwa","doi":"10.1016/j.expthermflusci.2025.111456","DOIUrl":"10.1016/j.expthermflusci.2025.111456","url":null,"abstract":"","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"165 ","pages":"Article 111456"},"PeriodicalIF":2.8,"publicationDate":"2025-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143580535","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":"Heating at different zones on the airfoil: Experimental study on boundary layer flow and convection heat transfer scaling","authors":"Meijuan Dong ,&nbsp;Weimin Sang ,&nbsp;Guangjun Yang ,&nbsp;Jing Sun ,&nbsp;Feng Jiang","doi":"10.1016/j.expthermflusci.2025.111445","DOIUrl":"10.1016/j.expthermflusci.2025.111445","url":null,"abstract":"<div><div>For future wing layouts and delicate laminar-wing aircraft with full-surface anti-/de-icing requirements, electric heating technology offers the advantages of flexible heating positions, high thermal efficiency and environmental friendliness. However, in addition to achieving good protection, advanced anti-de-icing technology must also take into account the requirements of efficient aerodynamic design. To investigate the effects of different heating zones on heat transfer efficiency and flow pattern within the boundary layer of wing, 15 heating zones based on bus temperature control were constructed on the leading edge and upper surface of the NACA2412 standard airfoil model, and a wind tunnel test framework was built for the study of electro-thermal convection. This is because accurate quantification of the heat transfer efficiency and precise identification of the flow effects in the boundary layer, which are crucial for effective thermal management and satisfying aerodynamic design. Within the airfoil boundary layer, test results from four typical flow characterization zones were selected for elucidation, and the spatial distribution of velocity and temperature induced by each heating zone were quantitatively characterized. Subsequently, the convective heat transfer efficiency in each heat affected zone was demonstrated using convective heat resistance. The results show that: abrupt changes in the flow state of the boundary layer can have a significant truncation effect on the temperature distribution of the flow field, leading to significant differences in the heat diffusion and heat transfer efficiency in the influence aera; moderate heating before the boundary layer burst can effectively delay the end position of the transition; and the temperature boundary layer conditions show a bimodal peak after localized heating in the airfoil. The experimental data elucidate the effects of heating at different zones on the airfoil boundary, and this work contributes to non-isothermal flow field simulation and anti-deicing design.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"166 ","pages":"Article 111445"},"PeriodicalIF":2.8,"publicationDate":"2025-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143563738","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":"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}