Experimental Thermal and Fluid Science最新文献_第3页

Collisions between droplets of liquids of different viscosity and composite fuel particles 不同粘度液体液滴与复合燃料颗粒之间的碰撞

IF 3.3 2区工程技术 Q2 ENGINEERING, MECHANICAL

Experimental Thermal and Fluid Science

Pub Date : 2025-12-05 DOI: 10.1016/j.expthermflusci.2025.111669

Anastasia Islamova, Pavel Tkachenko, Nikita Shlegel, Stanislav Shulyaev, Pavel Strizhak

It is important to understand the physics of liquid droplet collisions for a variety of applications ranging from inkjet printing to composite fuel combustion. The use of composite fuels is associated with some challenges and limitations. It is necessary to study the collisions of droplets and particles used as slurry fuel components. The selected objects of research were water and oil droplets, as well as particles of pine, cedar, coal and filter cake. Typical collision regimes (agglomeration and destruction) were identified. The characteristics of child droplets and conditions of their interaction with droplets and particles were determined. Differences between the characteristics of interaction of combustible and noncombustible component droplets with particles were detected. Equations were presented for a mathematical description of transition boundaries between regimes on maps taking account of the dimensionless linear impact parameter, the Weber number and the Ohnesorge number. The decisive factor for agglomeration or separation of droplets and particles was the properties of liquid. If a particle was pre-wetted, the type and condition of its surface did not have a significant effect on interaction regimes. The occurrence of a regime was also found to depend on the particle shape. A comparison of interaction regime maps for liquid droplets and biomass particles in the experiments with water and motor oil revealed that the separation boundary for oil shifted towards 18–27 % higher Weber numbers. This is accounted for by the physical properties of the investigated liquids. Guidelines on using the research findings in the development of secondary atomization technologies of fuel droplets were provided.

从喷墨打印到复合燃料燃烧，了解液滴碰撞的物理特性非常重要。复合燃料的使用伴随着一些挑战和限制。液滴与颗粒作为浆液燃料组分，有必要对其碰撞进行研究。选取的研究对象为水滴和油滴，以及松、雪松、煤和滤饼的颗粒。确定了典型的碰撞机制（团聚和破坏）。确定了儿童液滴的特征及其与液滴和颗粒相互作用的条件。检测了可燃组分液滴与不可燃组分液滴与颗粒相互作用特性的差异。考虑了无因次线性冲击参数、Weber数和Ohnesorge数，给出了地图上区域间过渡边界的数学描述方程。液滴和颗粒团聚或分离的决定性因素是液体的性质。如果颗粒被预湿，其表面的类型和条件对相互作用机制没有显著影响。我们还发现，一个状态的出现与粒子的形状有关。在水和机油实验中，对液滴和生物质颗粒的相互作用谱图进行比较，发现油的分离边界向韦伯数高18 - 27%的方向移动。这是由所研究液体的物理性质来解释的。提出了将研究成果应用于燃料液滴二次雾化技术开发的指导方针。

{"title":"Collisions between droplets of liquids of different viscosity and composite fuel particles","authors":"Anastasia Islamova, Pavel Tkachenko, Nikita Shlegel, Stanislav Shulyaev, Pavel Strizhak","doi":"10.1016/j.expthermflusci.2025.111669","DOIUrl":"10.1016/j.expthermflusci.2025.111669","url":null,"abstract":"<div><div>It is important to understand the physics of liquid droplet collisions for a variety of applications ranging from inkjet printing to composite fuel combustion. The use of composite fuels is associated with some challenges and limitations. It is necessary to study the collisions of droplets and particles used as slurry fuel components. The selected objects of research were water and oil droplets, as well as particles of pine, cedar, coal and filter cake. Typical collision regimes (agglomeration and destruction) were identified. The characteristics of child droplets and conditions of their interaction with droplets and particles were determined. Differences between the characteristics of interaction of combustible and noncombustible component droplets with particles were detected. Equations were presented for a mathematical description of transition boundaries between regimes on maps taking account of the dimensionless linear impact parameter, the Weber number and the Ohnesorge number. The decisive factor for agglomeration or separation of droplets and particles was the properties of liquid. If a particle was pre-wetted, the type and condition of its surface did not have a significant effect on interaction regimes. The occurrence of a regime was also found to depend on the particle shape. A comparison of interaction regime maps for liquid droplets and biomass particles in the experiments with water and motor oil revealed that the separation boundary for oil shifted towards 18–27 % higher Weber numbers. This is accounted for by the physical properties of the investigated liquids. Guidelines on using the research findings in the development of secondary atomization technologies of fuel droplets were provided.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"173 ","pages":"Article 111669"},"PeriodicalIF":3.3,"publicationDate":"2025-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145748348","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}

引用次数: 0

Strategically located microchannel regions to enhance defrosting performance on vertical aluminum plates 策略性地定位微通道区域，以提高垂直铝板的除霜性能

IF 3.3 2区工程技术 Q2 ENGINEERING, MECHANICAL

Experimental Thermal and Fluid Science

Pub Date : 2025-12-03 DOI: 10.1016/j.expthermflusci.2025.111670

Margaret M. Hennessy, Rhett J. Bendure, Giancarlo Corti, Andrew D. Sommers

This work aims to improve defrosting performance in heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems while striking a balance in terms of the manufacturing cost. Minimizing the cost was achieved by mitigating the “edge effect” through microchannels (101.6 to 500 μm wide, 3.175 to 12.7 mm tall) that were strategically located along the bottom edge of vertical surfaces and then coupled in some cases with a fluorosilane coating. The “edge effect” refers to the phenomena where water droplets cling to the bottom edge of a vertical surface due to surface tension during drainage and are not removed. By treating only the bottom edge of the plate, manufacturing times were significantly reduced, and the defrosting performance remained comparable to fully-treated plates. Moreover, at T_w = -12 °C and RH = 60 % these plates improved defrosting percentages by as much as 20 % when compared to the baseline case, while also significantly reducing the manufacturing cost. Full-plate silica nanospring (SN) coatings were also studied and observed to have defrosting percentages as high as 90.3 %, but their current cost is not competitive for HVAC&R applications. General observations about surface defrosting performance in terms of efficiency metrics were also outlined and discussed.

这项工作旨在提高供暖、通风、空调和制冷（hvac&r）系统的除霜性能，同时在制造成本方面取得平衡。通过将微通道（101.6至500 μm宽，3.175至12.7 mm高）战略性地放置在垂直表面的底边，然后在某些情况下与氟硅烷涂层耦合，减轻了“边缘效应”，从而实现了成本的最小化。“边缘效应”是指水滴在排水过程中由于表面张力而附着在垂直表面的底边而不被清除的现象。通过只处理板的底部边缘，制造时间大大减少，并且除霜性能仍然与完全处理的板相当。此外，在Tw = -12°C和RH = 60%的情况下，与基线情况相比，这些板提高了20%的除霜百分比，同时也显著降低了制造成本。研究还发现，全板二氧化硅纳米弹簧（SN）涂层除霜率高达90.3%，但其目前的成本在暖通空调（HVAC&；R）应用中缺乏竞争力。从效率指标的角度对表面除霜性能的一般观察也进行了概述和讨论。

{"title":"Strategically located microchannel regions to enhance defrosting performance on vertical aluminum plates","authors":"Margaret M. Hennessy, Rhett J. Bendure, Giancarlo Corti, Andrew D. Sommers","doi":"10.1016/j.expthermflusci.2025.111670","DOIUrl":"10.1016/j.expthermflusci.2025.111670","url":null,"abstract":"<div><div>This work aims to improve defrosting performance in heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems while striking a balance in terms of the manufacturing cost. Minimizing the cost was achieved by mitigating the “edge effect” through microchannels (101.6 to 500 μm wide, 3.175 to 12.7 mm tall) that were strategically located along the bottom edge of vertical surfaces and then coupled in some cases with a fluorosilane coating. The “edge effect” refers to the phenomena where water droplets cling to the bottom edge of a vertical surface due to surface tension during drainage and are not removed. By treating only the bottom edge of the plate, manufacturing times were significantly reduced, and the defrosting performance remained comparable to fully-treated plates. Moreover, at <em>T</em><sub>w</sub> = -12 °C and RH = 60 % these plates improved defrosting percentages by as much as 20 % when compared to the baseline case, while also significantly reducing the manufacturing cost. Full-plate silica nanospring (SN) coatings were also studied and observed to have defrosting percentages as high as 90.3 %, but their current cost is not competitive for HVAC&R applications. General observations about surface defrosting performance in terms of efficiency metrics were also outlined and discussed.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"173 ","pages":"Article 111670"},"PeriodicalIF":3.3,"publicationDate":"2025-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145797528","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}

引用次数: 0

Research on the atomization characteristics and influencing factors of tangential centrifugal nozzles 切向离心喷嘴雾化特性及影响因素研究

IF 3.3 2区工程技术 Q2 ENGINEERING, MECHANICAL

Experimental Thermal and Fluid Science

Pub Date : 2025-12-02 DOI: 10.1016/j.expthermflusci.2025.111679

Changchun Liu , Cheng Xu , Kaiyang Wu , Haoyue Xi , Shijie Xin , Lei Bai

Understanding the atomization characteristics of tangential centrifugal nozzles is crucial for optimizing applications in combustion, fire suppression, and cooling. This study experimentally investigates the P-Q curves, droplet size distribution, spray cone angle, and velocity vector field of eight nozzles, which were experimentally measured. The calculation method of the swirl number (S_n) in tangential centrifugal atomizing nozzles was systematically established. The flow coefficient (C_D) of various nozzles and its mathematical relationship with the swirl number, inlet and outlet diameters, and Reynolds number were determined. Additionally, a dimensionless parameter (Π), characterizing the Sauter Mean Diameter (SMD), was constructed based on the Reynolds number and swirl number. Both the inlet Reynolds number (Re_in) and swirl intensity govern droplet size. SMD demonstrates a characteristic U-shaped dependency on Π, with minimum values occurring at 0.4 < Π < 1.2. Furthermore, higher pressures produce smaller SMD values. Swirl intensity significantly impacts the spray cone angle, with larger swirl numbers leading to wider angles. It was also observed that the spray cone angle produced by the nozzle is not strictly symmetrical about the outlet’s center axis but exhibits a certain offset angle. Particle Image Velocimetry (PIV) measurements revealed that droplets at higher swirl numbers (S_n ≥ 2.5) are predominantly concentrated on both sides of the flow field. In contrast, at lower swirl numbers (S_n < 2.5), the flow field becomes more sensitive to pressure changes, promoting droplet accumulation in the central region of the nozzle outlet axis.

了解切向离心喷嘴的雾化特性对于优化其在燃烧、灭火和冷却方面的应用至关重要。本文对实验测量的8个喷嘴的P-Q曲线、液滴尺寸分布、喷射锥角和速度矢量场进行了实验研究。系统地建立了切向离心雾化喷嘴内旋流数Sn的计算方法。确定了不同喷嘴的流量系数及其与旋流数、进出口直径和雷诺数之间的数学关系。此外，基于雷诺数和旋流数构建了表征Sauter平均直径（SMD）的无量纲参数（Π）。入口雷诺数（Rein）和涡流强度都决定了液滴的大小。SMD表现出对Π特有的u形依赖，最小值出现在0.4 <； Π < 1.2。此外，较高的压力产生较小的SMD值。旋流强度对喷淋锥角有显著影响，旋流数越大，喷淋锥角越大。还观察到喷嘴产生的喷锥角并非严格对称于出口中心轴，而是存在一定的偏置角。粒子图像测速（PIV）显示，高旋流数（Sn≥2.5）的液滴主要集中在流场两侧。相比之下，在较低的旋流数（Sn < 2.5）下，流场对压力变化更加敏感，促使液滴在喷嘴出口轴中心区域积聚。

{"title":"Research on the atomization characteristics and influencing factors of tangential centrifugal nozzles","authors":"Changchun Liu , Cheng Xu , Kaiyang Wu , Haoyue Xi , Shijie Xin , Lei Bai","doi":"10.1016/j.expthermflusci.2025.111679","DOIUrl":"10.1016/j.expthermflusci.2025.111679","url":null,"abstract":"<div><div>Understanding the atomization characteristics of tangential centrifugal nozzles is crucial for optimizing applications in combustion, fire suppression, and cooling. This study experimentally investigates the P-Q curves, droplet size distribution, spray cone angle, and velocity vector field of eight nozzles, which were experimentally measured. The calculation method of the swirl number (<em>S<sub>n</sub></em>) in tangential centrifugal atomizing nozzles was systematically established. The flow coefficient (<em>C<sub>D</sub></em>) of various nozzles and its mathematical relationship with the swirl number, inlet and outlet diameters, and Reynolds number were determined. Additionally, a dimensionless parameter (Π), characterizing the Sauter Mean Diameter (SMD), was constructed based on the Reynolds number and swirl number. Both the inlet Reynolds number (<em>Re<sub>in</sub></em>) and swirl intensity govern droplet size. SMD demonstrates a characteristic U-shaped dependency on Π, with minimum values occurring at 0.4 < Π < 1.2. Furthermore, higher pressures produce smaller SMD values. Swirl intensity significantly impacts the spray cone angle, with larger swirl numbers leading to wider angles. It was also observed that the spray cone angle produced by the nozzle is not strictly symmetrical about the outlet’s center axis but exhibits a certain offset angle. Particle Image Velocimetry (PIV) measurements revealed that droplets at higher swirl numbers (<em>S<sub>n</sub></em> ≥ 2.5) are predominantly concentrated on both sides of the flow field. In contrast, at lower swirl numbers (<em>S<sub>n</sub></em> < 2.5), the flow field becomes more sensitive to pressure changes, promoting droplet accumulation in the central region of the nozzle outlet axis.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"173 ","pages":"Article 111679"},"PeriodicalIF":3.3,"publicationDate":"2025-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145692351","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}

引用次数: 0

Advances in laser diagnostics for swirl combustion: current progress and future directions☆ 旋流燃烧激光诊断研究进展：现状与未来方向

IF 3.3 2区工程技术 Q2 ENGINEERING, MECHANICAL

Experimental Thermal and Fluid Science

Pub Date : 2025-11-30 DOI: 10.1016/j.expthermflusci.2025.111666

Guoqing Wang, Mingming Gu, Liangliang Xu, Shuyue Lai, Xi Xia, Fei Qi

Swirl combustion is a fundamental feature in modern energy conversion systems, particularly in gas turbines and aeroengines, where it enhances flame stabilization, mixing efficiency, and emissions control. The global shift toward low- and zero-carbon fuels, such as ammonia and hydrogen, introduces new challenges in swirl combustion environments, including altered flow dynamics, temperature distributions, and chemical reaction pathways. In this context, laser-based diagnostic techniques have undergone significant advances, enabling non-intrusive, high-resolution, time-resolved measurements of velocity fields, scalar distributions, and reaction zone structures in swirl-stabilized flames. This review summarizes recent progress in major laser diagnostic methods, including high-speed particle image velocimetry, planar laser-induced fluorescence, laser absorption spectroscopy, Rayleigh scattering, and Raman scattering based techniques. Developments in multiphysics and hybrid techniques are also discussed. Additionally, we emphasizes representative laser diagnostic advancements driven by high-temperature and low-carbon combustion technologies. The co-evolution of laser technology, diagnostic methods, and swirl combustion is discussed to show how advances in each area have accelerated progress in the others. Finally, the review outlines remaining scientific challenges, practical barriers to industrial application, and future research priorities, with emphasis on diagnostics for extreme conditions, AI-driven data analysis, and compact in-situ measurement solutions for next-generation swirl combustion systems.

涡流燃烧是现代能量转换系统的基本特征，特别是在燃气轮机和航空发动机中，它可以增强火焰稳定性，混合效率和排放控制。全球向低碳和零碳燃料（如氨和氢）的转变，给涡流燃烧环境带来了新的挑战，包括流动动力学、温度分布和化学反应途径的改变。在这种情况下，基于激光的诊断技术取得了重大进展，可以对旋涡稳定火焰中的速度场、标量分布和反应区结构进行非侵入式、高分辨率、时间分辨的测量。本文综述了高速粒子图像测速、平面激光诱导荧光、激光吸收光谱、瑞利散射和拉曼散射等主要激光诊断方法的最新进展。本文还讨论了多物理场和混合技术的发展。此外，我们强调由高温和低碳燃烧技术驱动的具有代表性的激光诊断进展。讨论了激光技术、诊断方法和涡流燃烧的共同发展，以显示每个领域的进步如何加速了其他领域的进步。最后，综述概述了仍然存在的科学挑战、工业应用的实际障碍和未来的研究重点，重点是极端条件的诊断、人工智能驱动的数据分析以及下一代涡流燃烧系统的紧凑型原位测量解决方案。

{"title":"Advances in laser diagnostics for swirl combustion: current progress and future directions☆","authors":"Guoqing Wang, Mingming Gu, Liangliang Xu, Shuyue Lai, Xi Xia, Fei Qi","doi":"10.1016/j.expthermflusci.2025.111666","DOIUrl":"10.1016/j.expthermflusci.2025.111666","url":null,"abstract":"<div><div>Swirl combustion is a fundamental feature in modern energy conversion systems, particularly in gas turbines and aeroengines, where it enhances flame stabilization, mixing efficiency, and emissions control. The global shift toward low- and zero-carbon fuels, such as ammonia and hydrogen, introduces new challenges in swirl combustion environments, including altered flow dynamics, temperature distributions, and chemical reaction pathways. In this context, laser-based diagnostic techniques have undergone significant advances, enabling non-intrusive, high-resolution, time-resolved measurements of velocity fields, scalar distributions, and reaction zone structures in swirl-stabilized flames. This review summarizes recent progress in major laser diagnostic methods, including high-speed particle image velocimetry, planar laser-induced fluorescence, laser absorption spectroscopy, Rayleigh scattering, and Raman scattering based techniques. Developments in multiphysics and hybrid techniques are also discussed. Additionally, we emphasizes representative laser diagnostic advancements driven by high-temperature and low-carbon combustion technologies. The co-evolution of laser technology, diagnostic methods, and swirl combustion is discussed to show how advances in each area have accelerated progress in the others. Finally, the review outlines remaining scientific challenges, practical barriers to industrial application, and future research priorities, with emphasis on diagnostics for extreme conditions, AI-driven data analysis, and compact in-situ measurement solutions for next-generation swirl combustion systems.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"173 ","pages":"Article 111666"},"PeriodicalIF":3.3,"publicationDate":"2025-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145692350","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}

引用次数: 0

Refuse derived fuels: Using near-infrared spectroscopy and machine learning to predict moisture content and dry particle spectra 垃圾衍生燃料：使用近红外光谱和机器学习来预测水分含量和干燥颗粒光谱

IF 3.3 2区工程技术 Q2 ENGINEERING, MECHANICAL

Experimental Thermal and Fluid Science

Pub Date : 2025-11-29 DOI: 10.1016/j.expthermflusci.2025.111678

J. Fischer , T. Kunz , K. Treiber , V. Scherer

Refuse derived fuel (RDF) sourced from industrial and municipal waste contains primarily plastics, paper/cardboard and textiles. Since RDF has high heating values and low prices, it is used as alternative fuel to coal in cement production, offering CO₂ reductions. However, the cement industry currently lacks real-time quality control of RDF, resulting in unnoticed reductions in heating value caused by elevated moisture content. Moisture content determination by drying takes up to 4 h, which does not allow for quick reactions in operation of the cement kiln.

This study addresses the challenge by applying near-infrared spectroscopy (NIRS) to predict the moisture content of paper and cardboard particles, which retains most moisture in RDF. The particles were moisturized by different methods with NIRS measurements at each stage. For the prediction, different approaches ranging from linear regression of selected wavelength absorptions to multiple machine learning regression techniques like ridge, lasso and multilayer perceptron are compared in accuracy and feature representation. The multilayer perceptron showed accurate results and robust feature selection, although also simple linear regression at selected wavelength gave adequate accuracy.

In a second step, moisture content and spectra of wet particles were used to predict the spectra of dry particles. These spectra are essential to correctly identify particle types or predict heating values, since training data consists of dry particle data. While linear models are not reaching acceptable results, both an autoencoder and a random forest regressor yielded spectra with correct shapes, which is sufficient for classification with derivative spectra.

来自工业和城市废物的垃圾衍生燃料（RDF）主要含有塑料、纸/纸板和纺织品。由于RDF具有高热值和低价格，它被用作水泥生产中煤炭的替代燃料，可以减少二氧化碳。然而，水泥行业目前缺乏RDF的实时质量控制，导致由于含水率升高而引起的热值未被注意到的降低。通过干燥来测定水分含量需要长达4小时，在水泥窑的操作中不允许快速反应。本研究通过应用近红外光谱（NIRS）来预测纸张和纸板颗粒的水分含量，这在RDF中保留了大部分水分。采用不同的方法对颗粒进行润湿，并在每个阶段进行近红外测量。对于预测，从选择波长吸收的线性回归到多机器学习回归技术（如ridge， lasso和多层感知器）的不同方法在准确性和特征表示方面进行了比较。多层感知器显示出准确的结果和鲁棒的特征选择，尽管在选择的波长上也有简单的线性回归给出了足够的精度。第二步，利用湿颗粒的水分含量和光谱来预测干颗粒的光谱。这些光谱对于正确识别颗粒类型或预测热值至关重要，因为训练数据由干燥颗粒数据组成。虽然线性模型没有达到可接受的结果，但自动编码器和随机森林回归器都产生了具有正确形状的光谱，这足以用于导数光谱的分类。

{"title":"Refuse derived fuels: Using near-infrared spectroscopy and machine learning to predict moisture content and dry particle spectra","authors":"J. Fischer , T. Kunz , K. Treiber , V. Scherer","doi":"10.1016/j.expthermflusci.2025.111678","DOIUrl":"10.1016/j.expthermflusci.2025.111678","url":null,"abstract":"<div><div>Refuse derived fuel (RDF) sourced from industrial and municipal waste contains primarily plastics, paper/cardboard and textiles. Since RDF has high heating values and low prices, it is used as alternative fuel to coal in cement production, offering CO<sub>2</sub> reductions. However, the cement industry currently lacks real-time quality control of RDF, resulting in unnoticed reductions in heating value caused by elevated moisture content. Moisture content determination by drying takes up to 4 h, which does not allow for quick reactions in operation of the cement kiln.</div><div>This study addresses the challenge by applying near-infrared spectroscopy (NIRS) to predict the moisture content of paper and cardboard particles, which retains most moisture in RDF. The particles were moisturized by different methods with NIRS measurements at each stage. For the prediction, different approaches ranging from linear regression of selected wavelength absorptions to multiple machine learning regression techniques like ridge, lasso and multilayer perceptron are compared in accuracy and feature representation. The multilayer perceptron showed accurate results and robust feature selection, although also simple linear regression at selected wavelength gave adequate accuracy.</div><div>In a second step, moisture content and spectra of wet particles were used to predict the spectra of dry particles. These spectra are essential to correctly identify particle types or predict heating values, since training data consists of dry particle data. While linear models are not reaching acceptable results, both an autoencoder and a random forest regressor yielded spectra with correct shapes, which is sufficient for classification with derivative spectra.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"173 ","pages":"Article 111678"},"PeriodicalIF":3.3,"publicationDate":"2025-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145692293","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}

引用次数: 0

Bubble oscillations and dynamics under periodic electric fields 周期电场作用下气泡振荡与动力学

IF 3.3 2区工程技术 Q2 ENGINEERING, MECHANICAL

Experimental Thermal and Fluid Science

Pub Date : 2025-11-25 DOI: 10.1016/j.expthermflusci.2025.111668

Tianle Gu, Samuel Siedel

Understanding bubble dynamics under time-dependent electric fields is essential for applications in electrohydrodynamic(EHD) control, microfluidics, and phase-change heat transfer, but the interplay of polarization and Coulomb forces in leaky dielectric fluids is poorly understood. In this study, we experimentally investigated the growth and detachment of air bubbles injected into the leaky dielectric liquid HFE-7100 under periodic electric fields with square and sine waveforms at 50 and 100 Hz. High-speed imaging and image analysis revealed that EHD forces induced significant shape oscillations and strongly influenced bubble growth rates and detachment timing. Quantitatively, Fast Fourier Transform (FFT) analysis of the 100 Hz square wave data revealed dominant oscillation frequencies clustered between 135 Hz and 211 Hz. The response was highly dependent on the phase of bubble initiation, with polarity reversal often triggering detachment. Notably, under sine wave excitation, successive bubbles spontaneously organized into two alternating modes characterized by highly consistent aspect ratio evolution and volumetric growth. The bifurcation effect disappeared when a DC bias was added to the signal. These results demonstrate the critical role of waveform shape, frequency, and polarity in modulating bubble behavior in periodic fields, and provide new experimental insight into transient EHD effects in leaky dielectric fluids.

了解随时间电场作用下的气泡动力学对于电流体动力学（EHD）控制、微流体和相变传热的应用至关重要，但对泄漏介质流体中极化和库仑力的相互作用了解甚少。本文实验研究了在50 Hz和100 Hz的方波和正弦波周期电场作用下，注入漏电介质HFE-7100中的气泡的生长和脱离。高速成像和图像分析显示，EHD力会引起明显的形状振荡，并强烈影响气泡的生长速度和脱离时间。定量地，对100 Hz方波数据进行快速傅里叶变换（FFT）分析显示，主要振荡频率聚集在135 Hz和211 Hz之间。反应高度依赖于气泡起始的阶段，极性反转常常触发分离。值得注意的是，在正弦波激励下，连续气泡自发组织成两种交替模式，其特征是高度一致的宽高比演化和体积增长。当信号中加入直流偏置时，分岔效应消失。这些结果证明了波形形状、频率和极性对周期场中调制气泡行为的关键作用，并为泄漏介质流体中的瞬态EHD效应提供了新的实验见解。

{"title":"Bubble oscillations and dynamics under periodic electric fields","authors":"Tianle Gu, Samuel Siedel","doi":"10.1016/j.expthermflusci.2025.111668","DOIUrl":"10.1016/j.expthermflusci.2025.111668","url":null,"abstract":"<div><div>Understanding bubble dynamics under time-dependent electric fields is essential for applications in electrohydrodynamic(EHD) control, microfluidics, and phase-change heat transfer, but the interplay of polarization and Coulomb forces in leaky dielectric fluids is poorly understood. In this study, we experimentally investigated the growth and detachment of air bubbles injected into the leaky dielectric liquid HFE-7100 under periodic electric fields with square and sine waveforms at 50 and 100 Hz. High-speed imaging and image analysis revealed that EHD forces induced significant shape oscillations and strongly influenced bubble growth rates and detachment timing. Quantitatively, Fast Fourier Transform (FFT) analysis of the 100 Hz square wave data revealed dominant oscillation frequencies clustered between 135 Hz and 211 Hz. The response was highly dependent on the phase of bubble initiation, with polarity reversal often triggering detachment. Notably, under sine wave excitation, successive bubbles spontaneously organized into two alternating modes characterized by highly consistent aspect ratio evolution and volumetric growth. The bifurcation effect disappeared when a DC bias was added to the signal. These results demonstrate the critical role of waveform shape, frequency, and polarity in modulating bubble behavior in periodic fields, and provide new experimental insight into transient EHD effects in leaky dielectric fluids.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"172 ","pages":"Article 111668"},"PeriodicalIF":3.3,"publicationDate":"2025-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145621054","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}

引用次数: 0

Experimental investigation of wettability dependence on the contact radius of hydrophobic surfaces using a photoelectric combination method 利用光电组合方法研究疏水表面接触半径对润湿性的影响

IF 3.3 2区工程技术 Q2 ENGINEERING, MECHANICAL

Experimental Thermal and Fluid Science

Pub Date : 2025-11-24 DOI: 10.1016/j.expthermflusci.2025.111667

Shiyu Zhang , Lingkun Han , Chuntian Liu

Hydrophobic surfaces are widely employed in both nature and industry. However, the dependence between the contact radius and the wettability of hydrophobic surfaces at different time scales has not been clearly established. Therefore, developing a method to measure the contact radius of these surfaces across multiple time scales is critical for understanding this relationship. This paper presented an innovative approach to contact radius measurement based on the photoelectric combination method, addressing the aforementioned challenges. By integrating electrical and optical techniques, this method leveraged the ultra-high spatiotemporal resolution of the electrical method to overcome the limitations of optical methods, particularly in capturing contact radius over short time intervals. An experimental setup was used to measure the contact radius of hydrophobic surfaces using this photoelectric combination method. The experimental results demonstrated that the contact radius remained unaffected by changes in wettability during the initial stage. However, as wettability decreased in the later stage, the contact radius significantly decreased.

疏水表面广泛应用于自然界和工业。然而，接触半径与疏水表面在不同时间尺度上的润湿性之间的依赖关系尚未明确确立。因此，开发一种方法来测量这些表面在多个时间尺度上的接触半径对于理解这种关系至关重要。针对上述问题，本文提出了一种基于光电组合法的接触半径测量方法。通过集成电学和光学技术，该方法利用电学方法的超高时空分辨率来克服光学方法的局限性，特别是在短时间间隔内捕获接触半径方面。在实验装置上，利用光电组合法测量了疏水表面的接触半径。实验结果表明，接触半径在初始阶段不受润湿性变化的影响。然而，随着后期润湿性的降低，接触半径显著减小。

{"title":"Experimental investigation of wettability dependence on the contact radius of hydrophobic surfaces using a photoelectric combination method","authors":"Shiyu Zhang , Lingkun Han , Chuntian Liu","doi":"10.1016/j.expthermflusci.2025.111667","DOIUrl":"10.1016/j.expthermflusci.2025.111667","url":null,"abstract":"<div><div>Hydrophobic surfaces are widely employed in both nature and industry. However, the dependence between the contact radius and the wettability of hydrophobic surfaces at different time scales has not been clearly established. Therefore, developing a method to measure the contact radius of these surfaces across multiple time scales is critical for understanding this relationship. This paper presented an innovative approach to contact radius measurement based on the photoelectric combination method, addressing the aforementioned challenges. By integrating electrical and optical techniques, this method leveraged the ultra-high spatiotemporal resolution of the electrical method to overcome the limitations of optical methods, particularly in capturing contact radius over short time intervals. An experimental setup was used to measure the contact radius of hydrophobic surfaces using this photoelectric combination method. The experimental results demonstrated that the contact radius remained unaffected by changes in wettability during the initial stage. However, as wettability decreased in the later stage, the contact radius significantly decreased.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"173 ","pages":"Article 111667"},"PeriodicalIF":3.3,"publicationDate":"2025-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145623448","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}

引用次数: 0

Experimental investigation of turbulence in non-Newtonian fluids using ultrasound velocity profiling 非牛顿流体湍流的超声速度谱实验研究

IF 3.3 2区工程技术 Q2 ENGINEERING, MECHANICAL

Experimental Thermal and Fluid Science

Pub Date : 2025-11-24 DOI: 10.1016/j.expthermflusci.2025.111665

B.K. Yusufi, Z. Kapelan , D. Mehta

Transportation of non-Newtonian fluids (NNFs) through pipelines is a cornerstone of modern infrastructure. While the laminar and transitional flows have been extensively studied, the turbulent behavior of NNFs remains poorly understood. This study investigates large-scale pipe-loop experiments on clay–water slurries, spanning Reynolds numbers

\approx 1.1 \times 1 0^{4} – 1.75 \times 1 0^{5}

in a 100-mm diameter facility. Using non-invasive ultrasound velocity profiling (UVP) together with wall shear stress measurements, we characterize flows ranging from weakly to highly non-Newtonian conditions with concentrations up to 19%(w/w). The experiments show that the transition to the log-law region is delayed and the log-law intercept shifts upward with increasing concentration, reflecting the redistribution of stresses as shear-thinning and yield effects become more pronounced. To further interpret these findings, the experimental observations were compared with established modeling approaches. Semi-empirical correlations exhibited intermediate performance (mean absolute error, MAE, up to 0.55 Pa for wall shear stress and 0.15 m/s for velocity), while the Launder–Spalding wall function performed worst due to its assumption of constant viscosity (MAE

\approx

1.48 Pa and 0.08 m/s). In contrast, the rheology-based wall function achieved the most reliable predictions, with minimal deviations from experiments (MAE

\approx

0.20 Pa for wall shear stress and 0.06 m/s for velocity). Overall, this work provides a comprehensive experimental and modeling assessment of turbulent non-Newtonian pipe flow at an industrial scale, yielding new insights into flow physics and establishing a valuable reference for future experimental and computational studies.

通过管道输送非牛顿流体（NNFs）是现代基础设施的基石。虽然层流和过渡流已经被广泛研究，但nnf的湍流行为仍然知之甚少。本研究在一个直径为100毫米的设备中，研究了粘土-水泥浆的大规模管环实验，其雷诺数≈1.1×104-1.75×105。利用无创超声速度剖面（UVP）和壁面剪切应力测量，我们描述了从弱到高度非牛顿条件下的流动，浓度高达19%（w/w）。实验表明，随着浓度的增加，向对数律区域的过渡延迟，对数律截距向上移动，反映了剪切减薄和屈服效应更加明显时应力的重新分布。为了进一步解释这些发现，将实验观察结果与已建立的建模方法进行了比较。半经验相关性表现出中等的表现（平均绝对误差，MAE，墙剪应力高达0.55 Pa，速度高达0.15 m/s），而laaid - spalding墙函数由于其恒定粘度的假设而表现最差（MAE≈1.48 Pa和0.08 m/s）。相比之下，基于流变学的壁面函数实现了最可靠的预测，与实验偏差最小（壁面剪切应力MAE≈0.20 Pa，速度MAE≈0.06 m/s）。总的来说，这项工作为工业规模的非牛顿管道湍流提供了全面的实验和建模评估，为流动物理提供了新的见解，并为未来的实验和计算研究奠定了有价值的参考。

{"title":"Experimental investigation of turbulence in non-Newtonian fluids using ultrasound velocity profiling","authors":"B.K. Yusufi, Z. Kapelan , D. Mehta","doi":"10.1016/j.expthermflusci.2025.111665","DOIUrl":"10.1016/j.expthermflusci.2025.111665","url":null,"abstract":"<div><div>Transportation of non-Newtonian fluids (NNFs) through pipelines is a cornerstone of modern infrastructure. While the laminar and transitional flows have been extensively studied, the turbulent behavior of NNFs remains poorly understood. This study investigates large-scale pipe-loop experiments on clay–water slurries, spanning Reynolds numbers <span><math><mrow><mo>≈</mo><mn>1</mn><mo>.</mo><mn>1</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>4</mn></mrow></msup><mtext>–</mtext><mn>1</mn><mo>.</mo><mn>75</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>5</mn></mrow></msup></mrow></math></span> in a 100-mm diameter facility. Using non-invasive ultrasound velocity profiling (UVP) together with wall shear stress measurements, we characterize flows ranging from weakly to highly non-Newtonian conditions with concentrations up to 19%(w/w). The experiments show that the transition to the log-law region is delayed and the log-law intercept shifts upward with increasing concentration, reflecting the redistribution of stresses as shear-thinning and yield effects become more pronounced. To further interpret these findings, the experimental observations were compared with established modeling approaches. Semi-empirical correlations exhibited intermediate performance (mean absolute error, MAE, up to 0.55 Pa for wall shear stress and 0.15 m/s for velocity), while the Launder–Spalding wall function performed worst due to its assumption of constant viscosity (MAE <span><math><mo>≈</mo></math></span> 1.48 Pa and 0.08 m/s). In contrast, the rheology-based wall function achieved the most reliable predictions, with minimal deviations from experiments (MAE <span><math><mo>≈</mo></math></span> 0.20 Pa for wall shear stress and 0.06 m/s for velocity). Overall, this work provides a comprehensive experimental and modeling assessment of turbulent non-Newtonian pipe flow at an industrial scale, yielding new insights into flow physics and establishing a valuable reference for future experimental and computational studies.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"172 ","pages":"Article 111665"},"PeriodicalIF":3.3,"publicationDate":"2025-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145621051","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}

引用次数: 0

A theoretical and experimental study on CCFL in a scaled-down model of a small modular reactor (SMR) hot leg 小型模块化反应堆热腿缩比模型中CCFL的理论与实验研究

IF 3.3 2区工程技术 Q2 ENGINEERING, MECHANICAL

Experimental Thermal and Fluid Science

Pub Date : 2025-11-23 DOI: 10.1016/j.expthermflusci.2025.111664

Jie Wan , Xin Ma , Huafa Chen , Wan Sun , Yang Liu , Ren Liang , Longxiang Zhu , Luteng Zhang , Qiang Lian , Simiao Tang , Liang-Ming Pan

The Counter-Current Flow Limitation (CCFL) phenomena in horizontal and horizontal-inclined pipes have been extensively studied in the past. In recent years, small modular reactors (SMR) have attracted widespread attention as an ideal energy source for offshore development, which have a compact design with a small length-to-diameter ratio of the hot leg. Therefore, in this study, air–water CCFL visualization experiments were conducted in a scaled-down model of a SMR hot leg. The results indicated that, as the gas flow rate increases, the flow can be divided into three distinct regions: the stratified-entrainment region, the liquid-level rising region, and the liquid-level falling region, with CCFL occurring in the liquid-level rising region. A sudden decrease in the liquid penetration flow rate, which was measured by weighing method, was adopted as the criterion for the onset of CCFL, and then the CCFL characteristic curve was obtained. The mechanisms of CCFL were investigated over different ranges of liquid flow rates based on the characteristic curve and the results of the visualization experiment. Finally, a force analysis of the gas–liquid counter-current flow was performed based on the experimental results, and the momentum equations for gas and liquid phases were established to develop a CCFL prediction model. In addition, to complete the new model, several existing interfacial friction factor models were evaluated, and a modified interfacial friction factor model was developed.

在过去，人们对水平和水平倾斜管道中的逆流限流现象进行了广泛的研究。近年来，小型模块化反应堆（SMR）由于其设计紧凑、热腿长径比小，作为海上开发的理想能源而受到广泛关注。因此，在本研究中，在SMR热腿的缩小模型中进行了空气-水CCFL可视化实验。结果表明：随着气体流量的增大，气流可分为层状夹带区、液面上升区和液面下降区3个明显的区域，其中CCFL发生在液面上升区；采用称重法测量液体穿透流速的突然下降作为CCFL发生的判据，得到CCFL特性曲线。根据特性曲线和可视化实验结果，研究了不同液体流量范围内CCFL的机理。最后，基于实验结果对气液逆流流进行了受力分析，建立了气液相动量方程，建立了CCFL预测模型。此外，为了完善新模型，对现有的几种界面摩擦因子模型进行了评价，并建立了一个改进的界面摩擦因子模型。

{"title":"A theoretical and experimental study on CCFL in a scaled-down model of a small modular reactor (SMR) hot leg","authors":"Jie Wan , Xin Ma , Huafa Chen , Wan Sun , Yang Liu , Ren Liang , Longxiang Zhu , Luteng Zhang , Qiang Lian , Simiao Tang , Liang-Ming Pan","doi":"10.1016/j.expthermflusci.2025.111664","DOIUrl":"10.1016/j.expthermflusci.2025.111664","url":null,"abstract":"<div><div>The Counter-Current Flow Limitation (CCFL) phenomena in horizontal and horizontal-inclined pipes have been extensively studied in the past. In recent years, small modular reactors (SMR) have attracted widespread attention as an ideal energy source for offshore development, which have a compact design with a small length-to-diameter ratio of the hot leg. Therefore, in this study, air–water CCFL visualization experiments were conducted in a scaled-down model of a SMR hot leg. The results indicated that, as the gas flow rate increases, the flow can be divided into three distinct regions: the stratified-entrainment region, the liquid-level rising region, and the liquid-level falling region, with CCFL occurring in the liquid-level rising region. A sudden decrease in the liquid penetration flow rate, which was measured by weighing method, was adopted as the criterion for the onset of CCFL, and then the CCFL characteristic curve was obtained. The mechanisms of CCFL were investigated over different ranges of liquid flow rates based on the characteristic curve and the results of the visualization experiment. Finally, a force analysis of the gas–liquid counter-current flow was performed based on the experimental results, and the momentum equations for gas and liquid phases were established to develop a CCFL prediction model. In addition, to complete the new model, several existing interfacial friction factor models were evaluated, and a modified interfacial friction factor model was developed.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"173 ","pages":"Article 111664"},"PeriodicalIF":3.3,"publicationDate":"2025-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145623449","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}

引用次数: 0

Sensitivity analysis of kirigami geometry on a rectangular cylindrical flow 基利伽米几何对矩形圆柱流的敏感性分析

IF 3.3 2区工程技术 Q2 ENGINEERING, MECHANICAL

Experimental Thermal and Fluid Science

Pub Date : 2025-11-23 DOI: 10.1016/j.expthermflusci.2025.111663

Hao Meng , Haoqi Hu , Shuaihang Lin , Haiyang Yu

This study investigated the impacts of kirigami scales on aerodynamic control in cylindrical structures, as well as their effectiveness in reducing aerodynamic forces and turbulence characteristics. Using particle image velocimetry (PIV) in wind tunnel experiments, we conducted detailed flow field measurements on rectangular prisms fitted with elliptical and triangular kirigami scales. The Reynolds number (Re) was set at (1.3–3.1) × 10⁴. The experimental findings revealed that the implemented scales effectively suppressed lift fluctuations and the distributions of Reynolds shear stress (RSS) and turbulent kinetic energy (TKE), achieving remarkable reduction efficiencies of 50 % and 70 %, respectively. By varying the shape and folding angles of the scales, we assessed their impact on flow field control, finding them particularly effective at large folding angles in suppressing pressure fluctuations and dynamic characteristics. The sensitivity to the folding angle varied among scales of different shapes. Notably, the kirigami scales demonstrated efficacy in mitigating Re-sensitivity for lift fluctuations within this range, though their drag reduction effect remained modest. Furthermore, through proper orthogonal decomposition (POD), we further analyzed the wake characteristics, demonstrating that kirigami scales can significantly alter the flow field structure, reduce energy concentrations, and thereby enhance the safety and lifespan of structures.

本文研究了基里伽米尺度对圆柱形结构气动控制的影响，以及它们在减少气动力和湍流特性方面的有效性。利用粒子图像测速技术（PIV）在风洞实验中对矩形棱镜进行了详细的流场测量。雷诺数Re设为（1.3 ~ 3.1）× 104。实验结果表明，所实施的尺度有效地抑制了升力波动和雷诺剪切应力（RSS）和湍流动能（TKE）的分布，分别达到50%和70%的显著降低效率。通过改变尺度的形状和折叠角度，我们评估了它们对流场控制的影响，发现它们在大折叠角度下对抑制压力波动和动态特性特别有效。不同形状的鳞片对折叠角的敏感性不同。值得注意的是，kirigami量表在此范围内有效地减轻了升力波动的re -敏感性，但其减阻效果仍然不大。此外，通过适当的正交分解（POD），我们进一步分析了尾迹特性，表明基里伽米尺度可以显著改变流场结构，降低能量浓度，从而提高结构的安全性和寿命。

{"title":"Sensitivity analysis of kirigami geometry on a rectangular cylindrical flow","authors":"Hao Meng , Haoqi Hu , Shuaihang Lin , Haiyang Yu","doi":"10.1016/j.expthermflusci.2025.111663","DOIUrl":"10.1016/j.expthermflusci.2025.111663","url":null,"abstract":"<div><div>This study investigated the impacts of kirigami scales on aerodynamic control in cylindrical structures, as well as their effectiveness in reducing aerodynamic forces and turbulence characteristics. Using particle image velocimetry (PIV) in wind tunnel experiments, we conducted detailed flow field measurements on rectangular prisms fitted with elliptical and triangular kirigami scales. The Reynolds number (<em>Re</em>) was set at (1.3–3.1) × 10<sup>4</sup>. The experimental findings revealed that the implemented scales effectively suppressed lift fluctuations and the distributions of Reynolds shear stress (RSS) and turbulent kinetic energy (TKE), achieving remarkable reduction efficiencies of 50 % and 70 %, respectively. By varying the shape and folding angles of the scales, we assessed their impact on flow field control, finding them particularly effective at large folding angles in suppressing pressure fluctuations and dynamic characteristics. The sensitivity to the folding angle varied among scales of different shapes. Notably, the kirigami scales demonstrated efficacy in mitigating <em>Re</em>-sensitivity for lift fluctuations within this range, though their drag reduction effect remained modest. Furthermore, through proper orthogonal decomposition (POD), we further analyzed the wake characteristics, demonstrating that kirigami scales can significantly alter the flow field structure, reduce energy concentrations, and thereby enhance the safety and lifespan of structures.</div></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"173 ","pages":"Article 111663"},"PeriodicalIF":3.3,"publicationDate":"2025-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145600615","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}

引用次数: 0