Experimental Thermal and Fluid Science最新文献

{"title":"Increased surface temperature at critical heat flux for single water droplet impact with alcohol additives","authors":"Chang Cai ,&nbsp;Chao Si ,&nbsp;Hong Liu","doi":"10.1016/j.expthermflusci.2025.111413","DOIUrl":"10.1016/j.expthermflusci.2025.111413","url":null,"abstract":"<div><div>Elevating the critical heat flux limit during droplet impact cooling is advantageous for the thermal management of various high-power equipment. This study presents the experimental observation that the surface temperature at the critical heat flux point decreases with droplet impact velocity. The findings also demonstrate that low-carbon alcohol additives at small concentrations markedly increase the critical heat flux temperature of an impacting water droplet. In particular, the critical heat flux temperatures of dilute alcoholic solution droplets at higher impact velocities exceed those of pure water droplets at lower impact velocities within the present test range. Accordingly, low-carbon alcohol additives at low volume fractions can assure high heat transfer rates at large Weber numbers while also reducing the detrimental effect of impact velocity on the critical heat flux temperature. The significantly increased critical heat flux temperature associated with low-carbon alcohol additives is supposed to be considerably favorable for efficient heat dissipation of high-heat-flux electronic components.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"163 ","pages":"Article 111413"},"PeriodicalIF":2.8,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134920","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 surge propagation and discharge calculation in a sloping circular pipe","authors":"Jinlong Zuo ,&nbsp;Tibing Xu ,&nbsp;Yu Qian ,&nbsp;David Z. Zhu","doi":"10.1016/j.expthermflusci.2025.111409","DOIUrl":"10.1016/j.expthermflusci.2025.111409","url":null,"abstract":"<div><div>The generation and propagation of a positive surge in a sloping circular pipe were studied. Using a lab-scale model, positive surges were generated by rapidly closing a downstream gate, and the resulting flow patterns and surge propagation speeds were observed. The continuity and momentum equations were applied to derive an analytical solution for back-calculating discharge from measured surge speeds and hydraulic conditions. Experimental results showed the surge speed decreased with propagation distance, stabilizing beyond certain distances. The sequent depth ratio for positive surges was investigated, and the results showed that the sequent depth ratio for circular pipes was lower compared to that in a rectangular channel with the same Froude number. An equation was developed to evaluate the sequent depth ratio for positive surges in partially filled flow within a circular pipe. In practical applications, it is necessary to measure the initial water depth, the surge propagation distance, the average speed of the surge corresponding to this distance, and the water depth behind the surge wave front to estimate the discharge in the pipe. The results indicated that a longer observation distance from the disturbance location leads to a smaller error between the calculated and measured discharges, which is generally less than 10 % at measurement locations farther than 3 times the diameter length from the tailgate. Therefore, the proposed discharge calculation equation can be applied in sewer systems as an initial discharge estimation method for quick reference.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"163 ","pages":"Article 111409"},"PeriodicalIF":2.8,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134922","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":"Temporal instability and sheet breakup of a curved liquid sheet formed by jet impinging on a circular plane","authors":"Tianyu Kang (康天宇) ,&nbsp;Qingbo Yu (于庆波) ,&nbsp;Zhongyuan Liu (刘中元) ,&nbsp;Shengkai Tao (陶盛恺)","doi":"10.1016/j.expthermflusci.2025.111411","DOIUrl":"10.1016/j.expthermflusci.2025.111411","url":null,"abstract":"<div><div>For melt granulation, sheet breakup formed by melt jet impingement is an efficient treatment method. This paper theoretically and experimentally investigates the flow and breakup characteristics of a curved liquid sheet formed by jet impinging on a circular plane. The results show that the overall degree of sheet bending decreases with the increase in sheet velocity, which can be used to determine the streamline of liquid sheets by the configuration method. Based on the obtained knowledge of the sheet dynamic, the disturbance dispersion equation of a liquid sheet with variable velocity is derived first. In the instability analysis of the liquid sheet element, the acceleration force working due to the sheet bending stabilizes the sheet disturbance. However, combining the overall motion and instability of the liquid sheet shows that, with the sheet’s bending and spreading, the increasing sheet velocity and the decreasing sheet thickness still promote the development of sheet disturbance. For the dominant breakup mode, the bending of the liquid sheet contributes to the delay of sheet breakup for bell-like sheets at low velocity. In contrast, the bending of the liquid sheet contributes to the advance of sheet breakup for umbrella-like sheets at large velocity. For the critical jet Weber number, the experimental value of the curved sheet is less than that of the planar liquid sheet, due to the increase in sheet velocity. The prediction methods of breakup length and droplet radius are proposed.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"163 ","pages":"Article 111411"},"PeriodicalIF":2.8,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134921","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":"Advection-based multiframe iterative correction for pressure estimation from velocity fields","authors":"Junwei Chen,&nbsp;Marco Raiola,&nbsp;Stefano Discetti","doi":"10.1016/j.expthermflusci.2025.111407","DOIUrl":"10.1016/j.expthermflusci.2025.111407","url":null,"abstract":"<div><div>A novel method to improve the accuracy of pressure field estimation from time-resolved Particle Image Velocimetry data is proposed. This method generates several new time-series of velocity field by propagating in time the original one using an advection-based model, which assumes that small-scale turbulence is advected by large-scale motions. Then smoothing is performed at the corresponding positions across all the generated time-series. The process is repeated through an iterative scheme. The proposed technique smears out spatial noise by exploiting time information. Simultaneously, temporal jitter is repaired using spatial information, enhancing the accuracy of pressure computation via the Navier–Stokes equations. We provide a proof of concept of the method with synthetic datasets based on a channel flow and the wake of a 2D wing. Different noise models are tested, including Gaussian white noise and errors with some degree of spatial coherence. Additionally, the filter is evaluated on an experimental test case of the wake of an airfoil, where pressure field ground truth is not available. The result shows the proposed method performs better than conventional filters in velocity and pressure field estimation, especially when spatially coherent errors are present. The method is of direct application in advection-dominated flows, although its extension with more advanced models is straightforward.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"164 ","pages":"Article 111407"},"PeriodicalIF":2.8,"publicationDate":"2025-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143227272","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":"Exploring exudate absorption via sessile droplet dynamics in porous wound dressings","authors":"Avick Sinha ,&nbsp;Anastasios Georgoulas ,&nbsp;Cyril Crua ,&nbsp;Shirin Saberianpour ,&nbsp;Dipak Sarker ,&nbsp;Rachel Forss ,&nbsp;Matteo Santin","doi":"10.1016/j.expthermflusci.2025.111408","DOIUrl":"10.1016/j.expthermflusci.2025.111408","url":null,"abstract":"<div><div>Chronic wounds, typically defined as those that fail to reduce in size by at least 40% within a month, present a significant global socioeconomic challenge. In clinical practice, it is widely recognized that maintaining an optimal moisture balance in the wound while managing excess exudate is crucial for wound healing. Therefore, the selection of wound dressings is a key tool in wound management, which is based on their ability to sustain this delicate equilibrium. However, there is a notable lack of fundamental studies on the interaction between wound exudate and dressings, which limits the availability of evidence-based guidance for clinical practitioners. Thus, the present investigation explores how wound exudate interacts with different commercially available wound dressings to optimize wound management through a deep understanding of exudate-air interface dynamics in contact with the dressing material. Employing high-resolution imaging, the research delves into the behaviour of quasi-sessile droplets on various porous materials, analysing the impacts of exudate viscosity, blood sugar levels, and exudate volume. The findings reveal that droplet absorption rates depend on exudate properties and dressing materials. Notably, cellulose-based dressings outperform alginate and polyester-based alternatives in terms of wettability and imbibition capacity, with a performance improvement of at least 48%. Furthermore, increased exudate viscosity and elevated blood sugar are associated with longer absorption times, with increases of <span><math><mo>≈</mo></math></span> 51% and <span><math><mo>≈</mo></math></span> 38%, respectively. The study also identifies that absorption completion time increases exponentially with fibre diameter but decreases with greater pore radius and higher porosity. The overall findings can aid clinicians with quantitative insights to optimize the selection of wound dressings, thereby enhancing the healing of chronic wounds.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"163 ","pages":"Article 111408"},"PeriodicalIF":2.8,"publicationDate":"2025-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134919","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":"Quantifying the relationship between bubble surface area and gas evolution rate","authors":"Anirban Ghosh,&nbsp;Michael Angelo Miranda,&nbsp;Clint P. Aichele","doi":"10.1016/j.expthermflusci.2025.111412","DOIUrl":"10.1016/j.expthermflusci.2025.111412","url":null,"abstract":"<div><div>Bubbling is a common phenomenon in nearly all fields of engineering. For example, in gas/liquid separations, the mass transfer rate of gas exiting the liquid is affected by the bubbling of the system, and ultimately the area available for mass transfer. This study is aimed at understanding the influence of bubble surface area on gas evolution (mass transfer) behavior in liquids. Bubbling was characterized by three regimes:<!--> <!-->low bubbling, transitional bubbling, and high bubbling in the liquid during the mass transfer process. An optical technique was designed to determine bubble diameters using an HD camera. Observations of an increase in bubble surface area were directly correlated to an increase in the mass transfer rate. In addition, liquid viscosity was observed to play a major role in the bubbling behavior. Fluids with viscosity lower than 96 cP did not experience bubbling irrespective of mixing speeds during the gas evolution process. With an increase in the fluid viscosity, the ease of bubbling increased. Bubbling was not seen during the gas absorption process irrespective of fluid viscosity, indicating the bubbling phenomenon is a result of the gas evolution process.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"165 ","pages":"Article 111412"},"PeriodicalIF":2.8,"publicationDate":"2025-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143521042","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 concentration and period on the transient pool boiling heat transfer of Fe3O4-based aqueous nanofluids","authors":"Abutaleb Ramezani ,&nbsp;Ahmadreza Faghih Khorasani ,&nbsp;Ahmadreza Ayoobi","doi":"10.1016/j.expthermflusci.2024.111404","DOIUrl":"10.1016/j.expthermflusci.2024.111404","url":null,"abstract":"<div><div>The high conductivity of metal nanoparticles and the flowability of the base fluid led to significant changes in heat transfer rates when ferrofluids are used in the boiling process. Pool boiling tests were conducted in this study using Fe₃O₄/water ferrofluid at concentrations of 0.01 %, 0.05 %, and 0.1 % under transient conditions lasting from 1 s to 5000 s. In the present study, the ferrofluid was prepared through a two-step process. A horizontal nickel-chrome wire served as the heater and the heat flux was assessed as a quadratic polynomial function for each period, with a linear increase in applied voltage. Results showed that increasing nanoparticle concentration accelerates the onset of nucleate boiling (ONB) and raises critical heat flux (CHF) by up to 137 %. However, longer periods lead to delayed ONB, increased superheat temperature, a maximum 25 % reduction in CHF, and a maximum 96 % reduction in heat transfer coefficient at the CHF point in any given nanoparticle concentration. at concentrations of 0.01 %, 0.05 %, and 0.1 %, the heat transfer coefficient at the CHF point experiences a decline of 96.5 %, 95.15 %, and 89.7 %, respectively, with an increased period compared to the baseline period of t = 1 s.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"163 ","pages":"Article 111404"},"PeriodicalIF":2.8,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134758","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":"Evolution of droplet freezing front and surface temperature on cold surface under forced convection","authors":"Xueqiang Yuan ,&nbsp;Duo Zhang ,&nbsp;Yuan Wang ,&nbsp;Yu Pan ,&nbsp;Weidong Liu","doi":"10.1016/j.expthermflusci.2025.111410","DOIUrl":"10.1016/j.expthermflusci.2025.111410","url":null,"abstract":"<div><div>The evolution of freezing front and surface temperature in droplet freezing process under forced convection condition was studied. The influence mechanism of convective heat transfer on the droplet freezing front was explored through the surface temperature change. A prediction model for droplet freezing under forced convection was established by considering the effect of convective heat transfer. The results indicated that in the peak freezing mode, the rise of the freezing front is driven by the heat conduction of the cold surface, while in the peakless freezing mode, the freezing front will reach thermal equilibrium, and its movement is driven by the frost induced inter-droplet nucleation. Affected by the force-convective heat transfer, the temperature difference inside the droplet increases significantly. The higher droplet surface temperature on the windward makes the freezing front and isotherm tilt towards the windward. As airflow velocity increase, the larger convective heat transfer leads to slower temperature decrease in the solidification stage. By analyzing the freezing front moving process on the windward and leeward separately, the evolution of the freezing front and solidification time can be predicted accurately by the model for the peak freezing mode, and the calculated critical criterion for freezing mode transition agrees well with the experimental results.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"163 ","pages":"Article 111410"},"PeriodicalIF":2.8,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134870","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 of Dean-vortices oscillation downstream of a 90° Bend","authors":"Bilal Ben Haroual ,&nbsp;Julie Albagnac ,&nbsp;Pierre Brancher ,&nbsp;Sébastien Cazin ,&nbsp;Didier Boldo ,&nbsp;Emmanuel Thibert ,&nbsp;Romain Mathis","doi":"10.1016/j.expthermflusci.2024.111402","DOIUrl":"10.1016/j.expthermflusci.2024.111402","url":null,"abstract":"<div><div>The present work experimentally investigates the dynamics of a pipe flow downstream of a 90° bend in turbulent regime. The study is carried out on two different test benches, enabling to cover a decade in Reynolds numbers (<span><math><mrow><mi>R</mi><mi>e</mi><mo>∈</mo><mrow><mo>[</mo><mn>1</mn><mo>.</mo><mn>2</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>4</mn></mrow></msup><mo>,</mo><mspace></mspace><mn>5</mn><mo>.</mo><mn>4</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>5</mn></mrow></msup><mo>]</mo></mrow></mrow></math></span>). Laser-based metrology techniques are employed to capture the three velocity components in several flow sections, namely, cross-sections orthogonal to the main flow and vertical diametral planes (parallel to the main flow direction). Time-resolved and long-time decorrelated measurements allow the characterisation of both the dynamics and the statistics of the flow. These measurements highlight the behaviour of the fully three-dimensional flow generated downstream of the bend. In particular, an oscillation of the dipolar structure generated by the bend, known as the Dean vortices, is measured and analysed using a Lamb–Chaplygin analytical model. The dependency of the flow behaviour as a function of both the Reynolds number and the distance downstream of the bend and the return to axisymmetric flow are evaluated.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"163 ","pages":"Article 111402"},"PeriodicalIF":2.8,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134831","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":"An experimental study on gravity effect on frosting characteristics on surfaces of cold surface under natural convection","authors":"Fan Gao ,&nbsp;Mengjie Song ,&nbsp;Seyyed Hossein Hosseini ,&nbsp;Haikun Zheng ,&nbsp;Huan Su ,&nbsp;Yingjie Xu ,&nbsp;Sheng-Lun Lin","doi":"10.1016/j.expthermflusci.2024.111405","DOIUrl":"10.1016/j.expthermflusci.2024.111405","url":null,"abstract":"<div><div>Frosting phenomenon is widely seen in nature and also observed in space station. To deeply understand the gravity effect on frosting characteristics, and thus accurately predict and control the frosting process in space station, series of frosting experiments were designed and conducted on cold surface with three different placement angles at surface temperatures of −25 °C and −15 °C under natural convection. The results show that gravity primarily affects the frosting characteristics by changing the flow field of water vapor and the heat transfer capability near the frost layer surface. As cold surface placement moves from horizontal to vertical to inverted, the peak value of average frost layer thickness during the early stage increases to 206.43 × 10⁻⁶ m and 297.14 × 10⁻⁶ m, and the peak frosting rate is reduced to 4.98 × 10⁻⁶ m/s and 3.47 × 10⁻⁶ m/s throughout the whole frosting process, respectively. With the changing of cold surface placement, the time when the first reverse melting occurs on the frost layer surface was extended by 121.53 % and 57.37 %, the frequency of reverse melting was reduced by 30 % and 40 %, and the maximum value of reverse melting was reduced by 79.53 % and 91.09 %, respectively. This study could serve as a reference for frosting models, or development of anti-frosting or defrosting technologies in space station.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"163 ","pages":"Article 111405"},"PeriodicalIF":2.8,"publicationDate":"2024-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134858","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}