Experimental Thermal and Fluid Science最新文献

{"title":"Comparison of measured gas flux with Drift Flux Theory in a two-phase counter-current flow channel","authors":"Vaishakh Tholan ,&nbsp;Sascha Heitkam ,&nbsp;Anna-Elisabeth Sommer ,&nbsp;Muhammad Ziauddin ,&nbsp;Volker Recksiek ,&nbsp;Martin Rudolph ,&nbsp;Kerstin Eckert","doi":"10.1016/j.expthermflusci.2025.111479","DOIUrl":"10.1016/j.expthermflusci.2025.111479","url":null,"abstract":"<div><div>This experimental study aims to test the validity of the Drift Flux Theory (DFT) within a lab scale REFLUX^TM Flotation Cell (RFC^TM). The DFT, which is an analytical model, studies the transport conditions of rising bubbles in downward liquid flux. The model relates the component volumetric fluxes to the relative velocity between the liquid and gas phases and to their volume fractions. This requires measuring the local gas volume fraction and bubble diameter with high spatial and temporal resolution, which remains a challenge due to the limitations of existing sensors. To tackle this problem, newer sensors were used in the current study to revisit the hydrodynamics of the RFC^TM. In the current experimental setup, the gas fraction is measured using the Wire-Mesh Sensor, which has a high spatial and temporal resolution of <span><math><mrow><mn>0</mn><mo>.</mo><mn>5</mn><mspace></mspace><mstyle><mi>m</mi><mi>m</mi></mstyle></mrow></math></span> and <span><math><mrow><mn>10</mn><mspace></mspace><mstyle><mi>k</mi><mi>H</mi><mi>z</mi></mstyle></mrow></math></span> respectively. The bubble size distribution is measured in situ with an optical process microscope. The experimental parameters, such as gas flux, liquid flux, and wash-water fluxes, were changed to set different conditions in the model. These parameteric values were compared to predictions from the DFT which revealed significant deviations from the theoretical claims made on the basis of simplified transport conditions. The application of the drift-flux theory to highly turbulent multiphase flows, such as RFC^TM, must therefore be reviewed and requires further research.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"166 ","pages":"Article 111479"},"PeriodicalIF":2.8,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143737858","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 of unsteady fan-intake interactions using time-resolved stereoscopic particle image velocimetry","authors":"Matteo Migliorini,&nbsp;Pavlos K. Zachos,&nbsp;David G. MacManus,&nbsp;Alexandros Giannouloudis","doi":"10.1016/j.expthermflusci.2025.111482","DOIUrl":"10.1016/j.expthermflusci.2025.111482","url":null,"abstract":"<div><div>Understanding engine response to unsteady intake flow distortion is a crucial requirement to de-risk the development of novel aircraft configurations. This is more critical for configurations with highly embedded engines. Recent advances in non-intrusive, laser-based flow diagnostics demonstrated the ability to measure unsteady flows in convoluted intakes with high resolution in time and space. This work presents novel non-intrusive, unsteady flow measurements ahead of a fan rotor coupled to a convoluted diffusive intake. The fan rotor caused a local increase of the maximum levels of swirl intensity at the blade tip region, as well as flow re-distribution at the interface plane between the fan and the inlet duct compared to the baseline configuration with no fan in place. This contributed to the reduction of the overall swirl angle unsteadiness across the main flow distortion frequencies. This research presents a notable advance in unsteady fan-intake interaction characterisation. The work shows that high-resolution optical measurements offer notably better understanding of these complex aerodynamic interactions and have the potential to be part of larger scale, industrial testing programmes for future product development and certification.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"166 ","pages":"Article 111482"},"PeriodicalIF":2.8,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143705864","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":"Phase-locking PIV measurement of vortex–vortex interactions inside dual-slit cavity during high-intensity acoustic modulation","authors":"Yuchao Tang,&nbsp;Peng Wang,&nbsp;Yingzheng Liu","doi":"10.1016/j.expthermflusci.2025.111483","DOIUrl":"10.1016/j.expthermflusci.2025.111483","url":null,"abstract":"<div><div>This study experimentally investigates the vortex–vortex interaction mechanism inside a dual-slit cavity structure under high-intensity external acoustic modulation. Particular attention was paid to the slit distance, which corresponded to different vortex behaviors under the combined acoustic forcing effect and wall-confinement effect. A phase-locking particle image velocimetry measurement was performed using the incident acoustic wave as a phase-determination signal. The dynamically interactive response between acoustics and vortices was accurately phase-resolved through a field-programmable gate array with a precast wave decomposition method and a hard-computation approach. Four types of interaction mechanisms (rapid vortex merging, mutually interfered vortex shedding, isolated vortex evolution, and wall-confined vortex jets, with <span><math><mrow><msup><mrow><mi>S</mi></mrow><mrow><mo>∗</mo></mrow></msup><mo>=</mo></mrow></math></span> 2, 16, 32 and 49, respectively) were classified. Subsequent analysis on their vortex trajectory, convection velocity and kinetic energy consolidate our findings on the acoustic impedance and absorption characteristics, which are significantly reduced by the wall-confinement effect, whereas the vortex-merging effect can have a positive augmentation effect. Finally, multi-scale analysis by proper orthogonal decomposition (POD) and turbulence-production theory was conducted on the interactive vortex structures. POD identified the dominant energy distribution and demonstrated that vortex merging will disrupt the independent periodic wavepacket distribution and make the energy distribution mixed. Meanwhile, the production and dissipation processes of small-scale turbulence structures were identified, accompanying with the variations of turbulence stresses by the interactive vortex structures.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"166 ","pages":"Article 111483"},"PeriodicalIF":2.8,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143705863","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":"An efficient offline sensor placement method for flow estimation","authors":"Junwei Chen,&nbsp;Marco Raiola,&nbsp;Stefano Discetti","doi":"10.1016/j.expthermflusci.2025.111448","DOIUrl":"10.1016/j.expthermflusci.2025.111448","url":null,"abstract":"<div><div>We present an efficient method to optimize sensor placement for flow estimation using sensors with time-delay embedding in advection-dominated flows. Our solution allows identifying promising candidates for sensor positions using solely preliminary flow field measurements with non-time-resolved Particle Image Velocimetry (PIV), without introducing physical probes in the flow. Data-driven estimation in advection-dominated flows often exploits time-delay embedding to enrich the sensor information for the reconstruction, i.e. it uses the information embedded in probe time series to provide a more accurate estimation. Optimizing the probe position is the key to improving the accuracy of such estimation. Unfortunately, the cost of performing an online combinatorial search to identify the optimal sensor placement in experiments is often prohibitive. We leverage the principle that, in advection-dominated flows, rows of vectors from PIV fields embed similar information to that of probe time series located at the downstream end of the domain. We propose thus to optimize the sensor placement using the row data from non-time-resolved PIV measurements as a surrogate of the data a real probe would actually capture in time. This optimization is run offline and requires only one preliminary experiment with standard PIV. Once the optimal positions are identified, the probes can be installed and operated simultaneously with the PIV to perform the time-resolved field estimation. We show that the proposed method outperforms equidistant positioning or greedy optimization techniques available in the literature.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"167 ","pages":"Article 111448"},"PeriodicalIF":2.8,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143855073","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 Characterization of non-isothermal sloshing in microgravity","authors":"F. Monteiro ,&nbsp;P.A. Marques ,&nbsp;A. Simonini ,&nbsp;L. Carbonnelle ,&nbsp;M.A. Méndez","doi":"10.1016/j.expthermflusci.2025.111473","DOIUrl":"10.1016/j.expthermflusci.2025.111473","url":null,"abstract":"<div><div>Sloshing of cryogenic liquid propellants can significantly impact a spacecraft’s mission safety and performance by unpredictably altering the center of mass and producing large pressure fluctuations due to the increased heat and mass transfer within the tanks. This study, conducted as part of the NT-SPARGE (Non-isoThermal Sloshing PARabolic FliGht Experiment) project, provides a detailed experimental investigation of the thermodynamic evolution of a partially filled upright cylindrical tank undergoing non-isothermal sloshing in microgravity. Sloshing was induced by a step reduction in gravity during the 83<span><math><mtext>rd</mtext></math></span> European Space Agency (ESA) parabolic flight, resulting in a chaotic reorientation of the free surface under inertia-dominated conditions. To investigate the impact of heat and mass transfer on the sloshing dynamics, two identical test cells operating with a representative fluid, HFE-7000, in single-species were considered simultaneously. One cell was maintained in isothermal conditions, while the other started with initially thermally stratified conditions. Flow visualization, pressure, and temperature measurements were acquired for both cells. The results highlight the impact of thermal mixing on liquid dynamics coupled with the significant pressure and temperature fluctuations produced by the destratification. The comprehensive experimental data gathered provide a unique opportunity to validate numerical simulations and simplified models for non-isothermal sloshing in microgravity, thus contributing to improved cryogenic fluid management technologies.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"166 ","pages":"Article 111473"},"PeriodicalIF":2.8,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143696891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of physical properties of coal slurry droplets on their interaction with coal particles","authors":"Anastasia Islamova,&nbsp;Nikita Shlegel,&nbsp;Pavel Strizhak","doi":"10.1016/j.expthermflusci.2025.111478","DOIUrl":"10.1016/j.expthermflusci.2025.111478","url":null,"abstract":"<div><div>The use of alternative slurry fuels is a well-known approach to reducing hazardous emissions during combustion without a significant decrease in efficiency. Very little is currently known about the behavior of fuel droplets colliding with wall and with each other.<!--> <!-->It is important to understand these collisions to predict the processes characteristics during the spraying and subsequent combustion of a slurry fuel in a boiler furnace. Experiments into the collisions characteristics of coal-water slurry droplets were conducted, when varying the viscosity, density and surface tension of the slurry containing different sizes solid coal particles. The rheological characteristics of the slurry were varied by using such additives as transformer oil, neonol, emulsifier D_cD, Tween-20 and Tween-80. The use of surfactants was found to reduce the critical resultant velocity of a droplet sufficient for its breakup. The obtained data were compared with earlier findings. It was established that the fuel compositions are non-Newtonian fluids that demonstrate different secondary atomization characteristics. Nevertheless, droplet-particle interaction regimes tended to be very similar, which is accounted for by inhomogeneity of liquids. A chart was also produced to illustrate the use of identified specific aspects of interaction of slurry droplets with solid particles in thermal engineering applications.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"166 ","pages":"Article 111478"},"PeriodicalIF":2.8,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143681832","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":"GDI spray wall impingement against a heated and instrumented wall","authors":"Raúl Payri,&nbsp;Francisco Javier Salvador,&nbsp;Jaime Gimeno,&nbsp;César Carvallo","doi":"10.1016/j.expthermflusci.2025.111475","DOIUrl":"10.1016/j.expthermflusci.2025.111475","url":null,"abstract":"<div><div>Spray–wall interaction (SWI) is critical in the atomization, mixing, and combustion behavior of fuels and the formation of pollutant emissions. These elusive effects impact internal combustion engine performance and other engineering applications such as spray-induced cooling, painting, and solid deposit control. As a result, spray wall interactions are an active area of research. This article aims to use a thermoregulated steel wall to study the spray–wall interaction phenomenon. A multi-hole injector manufactured by Continental was used. Isooctane was employed as the injected fuel, and the wall was positioned at one distance from the injector tip and one inclination angle, changing the wall surface temperature, the injection pressure, the ambient back pressure, the ambient temperature, and the fuel temperature. The spray–wall heat transfer is analyzed, and the heat flux is measured by employing high-speed thermocouples fitted in the wall and using a one-dimensional transient wall heat model. The ambient and wall temperatures highly affect the amount of liquid in the spray. By increasing both temperatures, a lesser amount of liquid was found. For the range evaluated in the experimental campaign, the results revealed a significant increase in surface heat flow and wall temperature variance with both wall and fuel temperatures and the ambient temperature, but to a lesser extent.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"166 ","pages":"Article 111475"},"PeriodicalIF":2.8,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143705862","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 flow regime classification and riser pressure fluctuation characteristics in the long-distance pipeline S-shaped riser system","authors":"Yeqi Cao ,&nbsp;Qiang Xu ,&nbsp;Yuwen Li ,&nbsp;Bo Huang ,&nbsp;Haiyang Yu ,&nbsp;Liejin Guo","doi":"10.1016/j.expthermflusci.2025.111467","DOIUrl":"10.1016/j.expthermflusci.2025.111467","url":null,"abstract":"<div><div>Flow instability in the pipeline-riser is closely related to the fluctuation frequency and amplitude characteristics of the riser’s differential pressure. The gas–liquid overall and local flow regime distribution and flow characteristics in the long-distance pipeline S-shaped riser system with 46 mm ID and 1722 m length are investigated. An overall flow regime classification method based on the time-domain features, probability density distribution and power spectrum distribution of the riser’s differential pressure signal is proposed. The overall flow regimes SS, OSC, and ST1 at lower gas velocities (<em>V_SG</em>₀ &lt; 3.00 m/s) correspond to riser’s local flow regimes that exhibit a composite morphology of multiple single flow regimes in the vertical upward pipe, whereas the overall flow regime ST2 at higher gas velocities (<em>V_SG</em>₀ ≥ 3.00 m/s) shows the same single flow regime as that in the vertical upward pipe. Based on the gas phase Strouhal number and the no-slip liquid volume fraction, a correlation for predicting the fluctuation frequency of riser’s differential pressure is established. The fluctuation amplitude, minimum, maximum and asymmetry along the mean value of the riser’s differential pressure are associated with the overall flow regime, and a quantitative division criterion is proposed for predicting the unstable flow in the long-distance pipeline-riser system.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"166 ","pages":"Article 111467"},"PeriodicalIF":2.8,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143681879","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 transverse standing wave frequency and amplitude on oscillation and mode transition of partially premixed flame","authors":"Yue Lou ,&nbsp;Shoujun Ren ,&nbsp;Yikai Li ,&nbsp;Ziming Yang ,&nbsp;Haiyan Chen ,&nbsp;Jiajia Lin","doi":"10.1016/j.expthermflusci.2025.111477","DOIUrl":"10.1016/j.expthermflusci.2025.111477","url":null,"abstract":"<div><div>Reasonable matching of the acoustic and the combustion field can effectively boost burner power density. This study investigates the oscillation modes of the flame and the mechanism of mode transition under periodic acoustic excitation at different frequencies and amplitudes. Visualize the reaction zone by capturing OH* chemiluminescence images with a 307.15 nm filter and an ICCD camera. The intensity fluctuation of OH* and modal transitions of flame are analyzed using Fast Fourier Transform (FFT) and Proper Orthogonal Decomposition (POD) methods. The results show that flame disturbances from transverse standing waves depend on both the strength and duration of the acoustic field. A displacement oscillation factor (<em>p</em>*/<em>St</em>²) is used to describe how the acoustic field affects the flame front. When <em>p</em>*/<em>St</em>2 is low, the acoustic field causes small-amplitude transverse symmetrical oscillations at the flame’s edges. As <em>p</em>*/<em>St</em>² increases, vertical oscillations appear at the flame head, and the oscillation frequency of the flame matches the excitation frequency. High-intensity OH* chemiluminescence region is observed near the oscillation center. When <em>p</em>*/<em>St</em>² is excessive, the acoustic excitation creates macro flow that causes the flame into transverse oscillation, causing local blowout, periodic disruption, and a decrease in OH* intensity. The flame heat release intensity, indicated by OH* brightness, peaks near the condition of flame mode transitions from vertical to transverse oscillation.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"166 ","pages":"Article 111477"},"PeriodicalIF":2.8,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143637270","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":"Influence of the side ratio and main longitudinal beam shape on vortex-induced vibration and aerodynamic force characteristics of Π-shaped composite girders","authors":"Kaiwen Li ,&nbsp;Yifei Sun ,&nbsp;Qingkuan Liu ,&nbsp;Binxuan Wang ,&nbsp;Qingcai Wang ,&nbsp;Heng Cao","doi":"10.1016/j.expthermflusci.2025.111474","DOIUrl":"10.1016/j.expthermflusci.2025.111474","url":null,"abstract":"<div><div>Π-shaped composite girders in long-span bridges are prone to vortex-induced vibrations (VIVs). Therefore, it is important to study their VIV characteristics and corresponding countermeasures. In the present study, the effects of the side ratio (<em>B</em>/<em>H</em> = 7.00–14.00, where <em>B</em> and <em>H</em> represent the width and height of the girder, respectively), the bottom plate width of the main longitudinal beam (<em>b</em> = 0.30<em>H</em>–1.50<em>H</em>), and the inclination angle (<em>β</em> = -20°–30°) on VIVs, aerodynamic characteristics, and flow patterns were comprehensively compared. Additionally, the mechanisms underlying VIV suppression were preliminarily explored. The results indicate that the side ratio and the shape of the main longitudinal beam of the Π-shaped composite girder significantly affect the VIVs. However, the influence patterns differ and are highly related to the wind attack angle and vibration mode (vertical and torsional). The distribution patterns and values of the mean and fluctuating pressure coefficients on the upper and lower surfaces of the Π-shaped composite girder are different. These are notably influenced by the side ratio and <em>β</em> but are almost unaffected by <em>b</em>. VIVs are typically suppressed when the surface pressure frequency distribution becomes scattered and the pressure amplitude spectrum shows no distinct dominant frequency. Additionally, A reduction in the size of surface vortices is beneficial for controlling vertical VIVs. However, when the vortices are concentrated at the front of the model, they will induce torsional VIV. Within the studied parameter range, the optimal parameter combination for suppressing VIVs is <em>B</em>/<em>H</em> = 10.00, <em>b</em> ≥ 1.00<em>H</em>, and <em>β</em> = 10°. In general, practical engineering applications should consider specific conditions, such as the characteristics of the incoming flow.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"166 ","pages":"Article 111474"},"PeriodicalIF":2.8,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143620301","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}