Experimental Thermal and Fluid Science最新文献

{"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}

{"title":"An assessment of event-based imaging velocimetry for efficient estimation of low-dimensional coordinates in turbulent flows","authors":"Luca Franceschelli ,&nbsp;Christian E. Willert ,&nbsp;Marco Raiola ,&nbsp;Stefano Discetti","doi":"10.1016/j.expthermflusci.2025.111425","DOIUrl":"10.1016/j.expthermflusci.2025.111425","url":null,"abstract":"<div><div>This study explores the potential of neuromorphic Event-Based Vision (EBV) cameras for data-efficient representation of low-order model coordinates in turbulent flows. Unlike conventional imaging systems, EBV cameras asynchronously capture changes in temporal contrast at each pixel, delivering high-frequency output with reduced data bandwidth and enhanced sensitivity, particularly in low-light conditions. Pulsed Event-Based Imaging Velocimetry (EBIV) is assessed against traditional Particle Image Velocimetry (PIV) through two synchronized experiments: a submerged water jet and airflow around a square rib in a channel. The assessment includes a detailed comparison of flow statistics and spectral content, alongside an evaluation of reduced-order modeling capabilities using Proper Orthogonal Decomposition (POD). The event stream from the EBV camera is converted into pseudo-snapshots, from which velocity fields are computed using standard PIV processing techniques. These fields are then compared after interpolation onto a common grid. Modal analysis demonstrates that EBIV can successfully identify dominant flow structures, along with their energy and dynamics, accurately discerning singular values, spatial modes, and temporal modes. While noise contamination primarily affects higher modes – less critical for flow control applications – overall performance remains robust. Additionally, comparisons of Low-Order Reconstruction (LOR) validate EBIV’s capability to provide reliable reduced-order models of turbulent flows, essential for flow control purposes. These findings position EBV sensors as a promising technology for real-time, imaging-based closed-loop flow control systems.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"164 ","pages":"Article 111425"},"PeriodicalIF":2.8,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143227273","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":"Corrigendum to “A study on the wake structure of an ascending submersible with silk flexible appendages using continuous wavelet transform and dynamic mode decomposition” [Exp. Therm. Fluid Sci. 160 (2025) 111323]","authors":"Fei Yan ,&nbsp;Gangqing Zhang ,&nbsp;Akira Rinoshika ,&nbsp;Bo Song ,&nbsp;Jian Zhang","doi":"10.1016/j.expthermflusci.2024.111354","DOIUrl":"10.1016/j.expthermflusci.2024.111354","url":null,"abstract":"","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"161 ","pages":"Article 111354"},"PeriodicalIF":2.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143175542","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":"Aerodynamic characterisation of isolated cycling wheels","authors":"Jiaqi Mao,&nbsp;Peng Zhou,&nbsp;Wei Yi,&nbsp;Xin Zhang","doi":"10.1016/j.expthermflusci.2025.111423","DOIUrl":"10.1016/j.expthermflusci.2025.111423","url":null,"abstract":"<div><div>This study evaluated the aerodynamic performance of isolated cycling wheels, including a 5-spoke wheel and a disc wheel, considering the effects of freestream velocity, wheel type, wheel rotation, and crosswinds. For the first time, the rotational torque of cycling wheels was characterised using a shaft-mounted torque transducer. Force and wake velocity measurements were conducted in a wind tunnel between <span><math><mrow><mn>10</mn><mspace></mspace><mtext>m/s</mtext></mrow></math></span> and <span><math><mrow><mn>22</mn><mspace></mspace><mtext>m/s</mtext></mrow></math></span>, where aerodynamics plays a dominant role in deciding overall resistance. The experimental results show that the wheel rotation has an opposite influence on the axial force of different wheels. A wake analysis effectively captured the influence of freestream velocity, wheel type, and wheel rotation on axial force. Results reveal that multiple vortical regions are formed in the lower wake of the rotating wheels, whereas the vortices in the upper wake are suppressed due to wheel rotation. When crosswinds are present, the disc wheel exhibits thirty times larger steering torque and generates much stronger vortical structures. This study offers valuable insights into the wake behaviour and drag generation around cycling wheels.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"164 ","pages":"Article 111423"},"PeriodicalIF":2.8,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143139228","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":"Impingement of droplets with various liquid viscosities on a low-speed rotational surface","authors":"Wei Jia ,&nbsp;Yueyao Zheng ,&nbsp;Xiaoyu Cai","doi":"10.1016/j.expthermflusci.2025.111426","DOIUrl":"10.1016/j.expthermflusci.2025.111426","url":null,"abstract":"<div><div>The dynamic behavior of droplets with different liquid viscosities impacting a low-speed rotational surface was experimentally investigated. The effects of rotation and viscosity on the droplet morphology and spreading behavior were analyzed. The experimental results show that five typical morphologies-cap, splitting, deposition, secondary droplets, and lobes-exist in the droplet spreading on a rotational surface. The Rossby number and Ohnesorge number have important effects on the droplet morphologies. At a high Rossby number (<em>Ro</em> &gt; 4), the droplet exhibits a cap shape at the end of the retraction stage because the inertial force plays a dominant role. At a low Rossby number (<em>Ro</em> &lt; 2), the droplet exhibits splitting or deposition on the rotational surface. Secondary droplets may appear under certain conditions for the droplets with medium or high viscosity owing to the interaction among the tangential force, viscous force, and surface tension. At a medium Rossby number, the droplet is mainly deposited or cap-shaped in the end. The phenomenon of lobes is independent of the Rossby number, but is related to the Ohnesorge number. The lobes appear only at a medium or low Ohnesorge number during droplet spreading and retraction. In addition, the spreading behavior of a droplet impacting a rotational surface can be divided into retraction mode, oscillatory equilibrium mode, and continuous spreading mode. Empirical models were proposed for the maximum circumferential wetting length and the maximum wetting time. For the retraction mode, the empirical models produce mean relative errors of 5.08 % and 7.76 % for the maximum circumferential wetting length and the maximum wetting time, respectively. For the oscillatory equilibrium mode, the empirical models produce mean relative errors of 4.79 % and 9.98 % for the maximum circumferential wetting length and the maximum wetting time, respectively. The agreement between the predicted and experimental results is improved significantly when both rotation and viscosity effects are considered.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"164 ","pages":"Article 111426"},"PeriodicalIF":2.8,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143377366","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 shock train oscillation suppression by a plasma jet in a supersonic isolator","authors":"Fuhao Chen ,&nbsp;Zhaoyang Tian ,&nbsp;Chengzhi Zhang ,&nbsp;Lei Shi","doi":"10.1016/j.expthermflusci.2025.111428","DOIUrl":"10.1016/j.expthermflusci.2025.111428","url":null,"abstract":"<div><div>In a real ramjet engine, combustion instability gives rise to an unstable combustion pressure, which in turn disrupts the shock train in the inlet isolator, thereby introducing operational risks. This paper investigates the potential of the plasma jet (PJ) in supersonic flow control through a series of cold flow tests conducted at constant and incremental back pressure at <em>Mach</em> 2.5 freestream flow, respectively. As the pressure of the working material increases, the stable core region of the PJ expands, thereby demonstrating enhanced control capabilities. In the supersonic inlet isolator, the vertically injected PJ is compressed and induces a strong shock wave that dominates the downstream flow field. The shock wave induced by the PJ interacts with the leading-edge shock wave and results in a slight upstream movement of the shock train. The self-excited oscillation is suppressed with the implementation of the plasma actuator. The spatial FFT analysis indicates a reduction in both the oscillation frequency and the oscillation range of the leading-edge shock wave, with a suppression rate of 37.44% for the range. The PJ facilitates the momentum exchange near the shear layer and redistributes the oscillation energy. The dominant shock wave propagates the oscillation energy to the lower wall, thereby equalizing the energy distribution. Further studies on forced moving features demonstrate that the PJ effectively reduces low-frequency oscillation energy by at least 43.63% under incremental back pressure and achieves better control efficiency closer to the shock train. The high-frequency environment generated by the PJ and the shock wave induced by the PJ are considered the important factors in suppressing both self-excited and forced-excited oscillation of the shock train.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"163 ","pages":"Article 111428"},"PeriodicalIF":2.8,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134856","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":"Normalization of wettability and heat transfer coefficient curve prediction model on biphilic surfaces","authors":"Yindong Song ,&nbsp;Linfeng Xiang ,&nbsp;Xiuwei Cheng ,&nbsp;Dongshu Yang ,&nbsp;Kambiz Vafai","doi":"10.1016/j.expthermflusci.2025.111427","DOIUrl":"10.1016/j.expthermflusci.2025.111427","url":null,"abstract":"<div><div>The application of “biphilic surfaces” in boiling heat transfer has attracted widespread attention, and scholars have conducted numerous experimental studies in this field. Unfortunately, the relevant theoretical research is almost blank, especially in predicting essential parameters such as HTC. Therefore, it is necessary to develop a new correlation for the HTC of biphilic surfaces in boiling heat transfer. Firstly, in this study, biphilic surfaces composed of pure copper and Ag(S(CH₂)₁₇CH₃) were prepared using standard photolithography and chemical etching techniques. All of the surfaces feature 1000 μm square patterns, but there are variations in the contact angles (120.4°, 124.5°, 130.3°, 135°, 140°) of the hydrophobic surfaces. The maximum critical heat flux was 1203.5 kW/m², and the maximum heat transfer coefficient was 77.8 kW/m²K. Secondly, this study proposed the characteristic contact angle <em>θ_char</em>, which solves the issue of representing the wettability of biphilic surfaces with two contact angles. Next, the paper verified reliability of normalization process by combining the theory of homogeneous surfaces. Finally, this paper analyzed the undetermined coefficients in Rohsenow’s correlation by <em>θ_char</em>, enabling the prediction of HTC for biphilic surfaces. Compared with experimental data, the maximum prediction error does not exceed 24.13 %.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"164 ","pages":"Article 111427"},"PeriodicalIF":2.8,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143139227","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}