Experimental Thermal and Fluid Science最新文献_第10页

Roles of the centrifugal stage in the aerodynamic instability of a multistage combined compressor 离心级在多级组合式压气机气动失稳中的作用

IF 3.3 2区工程技术 Q2 ENGINEERING, MECHANICAL

Experimental Thermal and Fluid Science

Pub Date : 2025-07-23 DOI: 10.1016/j.expthermflusci.2025.111571

Jiaan Li , Baotong Wang , Xinqian Zheng

Aerodynamic instability could deteriorate the performance and structural integrity of a compression system. It has been an important issue in both the engineering and academic fields. Fewer studies have focused on the instability mechanism and behavior of combined compressors consisting of both axial and centrifugal-type stages, which have distinct pressurization capability and instability mechanism from each other. This paper concentrates on the influence of the centrifugal stage in a combined compressor on the overall aerodynamic stability. First, an experiment is carried out to investigate its instability characteristics. Then, a multi-actuator dynamic model is established to further analyze the influence of the centrifugal stage on the combined compressor instability from two aspects, the stage matching and the B parameter. To decouple these two factors, B parameters are increased above the critical value, eliminating its effect on the surge boundary only to investigate the influence of stage matching. Results show that when a stage performance curve with pressure ratio against mass flow rate has a negative slope near the matching point, the centrifugal stage has a stabilizing effect on the overall stability. In contrast, this stage has a detrimental influence when matched on the performance curve with a positive slope. For B parameter effects, a large value of B parameter generally narrows the stable operating range. Therefore, the influence of the centrifugal stage is determined by the balance of the above two aspects. Generally, for a combined compressor in a real industrial application, the change of B parameter by the centrifugal stage has more obvious effects on the overall stability than the stage matching because the centrifugal stage generally has a larger pressurization capability, resulting in a larger value of B parameter. Therefore, both stage matching and B parameter effect should be carefully considered for the stability design of a combined compressor consisting of stages with clear pressurization capability differences, compared with the individual axial or centrifugal compressor including the stages with similar pressurization capability.

气动不稳定性会降低压缩系统的性能和结构完整性。它一直是工程和学术领域的一个重要问题。轴向级和离心式级组合压气机的失稳机理和失稳行为研究较少，两者的增压能力和失稳机理各不相同。本文主要研究组合式压气机离心级对整体气动稳定性的影响。首先，对其失稳特性进行了实验研究。然后，建立多作动器动力学模型，从级匹配和B参数两个方面进一步分析离心级对组合式压缩机不稳定性的影响。为了解耦这两个因素，将B参数增加到临界值以上，消除其对浪涌边界的影响，仅研究级匹配的影响。结果表明，当压力比与质量流量的级性能曲线在匹配点附近呈负斜率时，离心级对整体稳定性具有稳定作用。相反，当该阶段与正斜率的性能曲线匹配时，则会产生不利影响。对于B参数的影响，B参数的较大值通常会缩小稳定的工作范围。因此，离心级的影响是由以上两个方面的平衡决定的。通常，对于实际工业应用中的组合式压缩机，由于离心级一般具有更大的增压能力，因此离心级对B参数的改变对整体稳定性的影响比级匹配更明显，从而导致B参数值更大。因此，对于增压能力差别明显的级组成的组合式压缩机，与增压能力相近的单轴式或离心式压缩机相比，在稳定性设计时应慎重考虑级匹配和B参数效应。

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引用次数: 0

On the interaction of vortical structures and shear layer in turbulent flow around trapezoidal prisms with varying aspect ratios 不同宽高比梯形棱柱周围湍流中旋涡结构与剪切层的相互作用

IF 2.8 2区工程技术 Q2 ENGINEERING, MECHANICAL

Experimental Thermal and Fluid Science

Pub Date : 2025-07-20 DOI: 10.1016/j.expthermflusci.2025.111570

Fati Bio Abdul-Salam , Amir Sagharichi , Xingjun Fang , Mark F. Tachie

The spatiotemporal dynamics of turbulent flow induced by trapezoidal prisms in a uniform flow are studied using time-resolved particle image velocimetry (TR-PIV). Three prisms with aspect ratios (AR, defined as the ratio between lower surface length and height) of 1, 2, and 3 (denoted as AR1, AR2, and AR3, respectively) were tested at a Reynolds number of 10000 based on the incoming velocity and prism height. In the wake region of the prisms, two recirculation bubbles form. For the AR1 prism, the bubbles are almost symmetric in size, whereas for AR2 and AR3 prisms, the upper bubble is significantly larger than the lower one. The peak values of the Reynolds stresses in the wake region decrease with increasing AR. Quadrant analysis reveals that the strength of sweep and ejection events increases with decreasing aspect ratio, enhancing flow recovery within the recirculation zone. The vertical derivative of Reynolds shear stress plays a major role in the higher flow recovery for AR1, but as the aspect ratio increases to 3, the vertical derivative of tangential momentum becomes the dominant factor. The nondimensional fundamental shedding frequencies for the AR1 and AR2 prisms are 0.13 and 0.11, respectively, whereas dual shedding frequencies of 0.05 and 0.12 are observed for the AR3 prism. Frequency synchronization induced by von Kármán (VK) vortex shedding remains strong from the leading edge to the wake region in the cases of AR1 and AR2 while becoming limited to the wake region for AR3.

采用时间分辨粒子图像测速技术（TR-PIV）研究了均匀流动中梯形棱镜引起的湍流的时空动力学。根据入射速度和棱镜高度，在雷诺数为10000的条件下，测试了三个长宽比（AR，定义为下表面长度与高度之比）分别为1、2和3的棱镜（分别记为AR1、AR2和AR3）。在棱镜的尾迹区，形成两个再循环气泡。对于AR1棱镜，气泡的大小几乎是对称的，而对于AR2和AR3棱镜，上部气泡明显大于下部气泡。尾迹区的峰值雷诺数随增径比的增大而减小。象限分析表明，随着展弦比的减小，掠流和喷射事件的强度增大，增强了再循环区内的流动恢复。雷诺数剪应力的垂直导数对AR1的高采收率起主要作用，但当展弦比增加到3时，切向动量的垂直导数成为主导因素。AR1和AR2棱镜的无量纲基本脱落频率分别为0.13和0.11，而AR3棱镜的双脱落频率为0.05和0.12。在AR1和AR2中，由von Kármán （VK）涡脱落引起的频率同步从前缘到尾迹区域保持强烈，而在AR3中则局限于尾迹区域。

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引用次数: 0

Comparison of background-oriented Schlieren and retroreflective shadowgraph visualizations of sand burner fire 面向背景的纹影与反射影沙燃烧器火灾可视化的比较

IF 2.8 2区工程技术 Q2 ENGINEERING, MECHANICAL

Experimental Thermal and Fluid Science

Pub Date : 2025-07-19 DOI: 10.1016/j.expthermflusci.2025.111569

M.S. Sadeghi , Maryam Ghodrat , Duncan Sutherland , Albert Simeoni , Harald Kleine

Simultaneous records of background-oriented schlieren (BOS) images and retroreflective shadowgrams (RS) of a stationary sand burner flame are compared to demonstrate the capabilities of each method. The schlieren images from the BOS method are post-processed in the PIVlab software via the reference image sequencing style method. The shadowgrams obtained in the RS setup are enhanced by adjusting the levels and contrast of the images. The range of length scales, the spectra at each length scale, and the effect of a glass sidewall window on the resolution of the images are determined. It is found that adding glass as a sidewall reduces the resolution and thus the number of detected eddies, but dominant eddies with their energy remain unaffected. In addition, the convective heat transfer is calculated and analyzed for both visualization methods. The results show that, in the described system, the resolution of the BOS images is lower than that of the shadowgrams, so smaller eddies are not as clearly visible as in corresponding RS results. However, BOS has the advantage of more easily quantifying the parameters studied in the present work. The paper describes a novel BOS-calibrated RS technique to extract the heat transfer contours from shadowgrams, which complements a similar approach in which heat transfer is obtained from BOS images.

同时记录背景定向纹影（BOS）图像和反向反射阴影图（RS）的固定沙燃烧器火焰进行比较，以证明每种方法的能力。在PIVlab软件中，通过参考图像排序风格的方法对BOS方法得到的纹影图像进行后处理。通过调整图像的水平和对比度，增强了在RS设置中获得的阴影图。确定了长度尺度范围、各长度尺度下的光谱以及玻璃侧壁窗对图像分辨率的影响。发现添加玻璃作为侧壁降低了分辨率，从而降低了检测到的涡流数量，但主导涡流及其能量不受影响。此外，对两种可视化方法的对流换热进行了计算和分析。结果表明，在所描述的系统中，BOS图像的分辨率低于阴影图的分辨率，因此较小的涡流不像相应的RS结果那样清晰可见。然而，BOS的优点是更容易对本文研究的参数进行量化。本文描述了一种新的BOS校准RS技术，用于从阴影图中提取传热轮廓，这是对从BOS图像中获得传热的类似方法的补充。

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引用次数: 0

Blockage effects on flow around rectangular prisms in uniform flow 均匀流动中矩形棱镜绕流的阻塞效应

IF 2.8 2区工程技术 Q2 ENGINEERING, MECHANICAL

Experimental Thermal and Fluid Science

Pub Date : 2025-07-17 DOI: 10.1016/j.expthermflusci.2025.111567

Fati B. Abdul-Salam , Sedem Kumahor , Xingjun Fang , Ebenezer E. Essel , Mark F. Tachie

The influence of blockage ratio on the flow around a rectangular prism was experimentally investigated using a time-resolved particle image velocimetry system. Three different blockage ratios (BR = 2.5 %, 5 %, and 10 %) were tested, with a fixed streamwise aspect ratio (AR = 3) and a Reynolds number of 7500. The results indicate that, for BR = 2.5 %, the separated shear layer from the leading edge of the prism is shed directly into the wake, however, an increase of BR promotes the reattachment on the surface of the prism. The streamwise extent of the primary, secondary and wake recirculation bubbles decrease with an increase in blockage ratio. Distinct regions of positive and negative Reynolds shear stress manifest near the leading edge, with the transitioning interface shifting upstream with increasing BR. Turbulence production concentrates near the shear layer, with peak magnitude increasing and shifting upstream with BR. The growth rate of the shear layer is similar for the reattached test cases but decrease for the unattached test cases. The spatial coherence of the turbulent structures increases downstream, however, the effects of blockage significantly reduced the spatial coherence in the BR10 case. Frequency spectra and spectral decomposition of the Reynolds normal stresses revealed that increasing the blockage ratio increases the dominance of von Kármán vortex shedding. For higher blockage ratios, turbulence is primarily influenced by intermediate-scales associated with vortex shedding, with reduced contributions from low-frequency flapping and small-scale shear-layer instabilities. In contrast, the lower blockage ratio exhibits a more complex interplay of small, intermediate, and large-scales turbulence dynamics.

采用时间分辨粒子图像测速系统，实验研究了阻挡比对矩形棱镜周围流动的影响。测试了三种不同堵塞比（BR = 2.5%， 5%和10%），固定的流向展弦比（AR = 3）和7500雷诺数。结果表明，当BR = 2.5%时，从棱镜前缘分离的剪切层直接脱落到尾流中，而BR的增加促进了棱镜表面的再附着。随着堵塞比的增大，一次、二次和尾流再循环气泡的流向范围减小。前缘附近存在明显的正、负雷诺剪应力区域，过渡界面随着BR的增大而向上游移动。湍流产生主要集中在切变层附近，峰值强度随着BR的增大而增大，并向上游移动。剪切层的生长速率在重新连接的测试用例中是相似的，而在未连接的测试用例中是下降的。下游湍流结构的空间相干性增加，但BR10的阻塞效应显著降低了空间相干性。雷诺数法向应力的频谱和谱分解表明，堵塞比的增加增加了von Kármán涡旋脱落的优势。对于较高的阻塞比，湍流主要受与旋涡脱落相关的中尺度影响，低频扑动和小尺度剪切层不稳定性的影响较小。相比之下，较低的堵塞比表现出更复杂的小、中、大尺度湍流动力学的相互作用。

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引用次数: 0

Spatially resolved measurements of velocity fields in the reactive zone of a laminar non-premixed flame 层流非预混火焰反应区速度场的空间分辨测量

IF 2.8 2区工程技术 Q2 ENGINEERING, MECHANICAL

Experimental Thermal and Fluid Science

Pub Date : 2025-07-16 DOI: 10.1016/j.expthermflusci.2025.111556

Nicolás Mancilla , Nicolás Gutiérrez , Valentina Yap , Juan J. Cruz , Felipe Escudero , Rodrigo H. Hernández , Andrés Fuentes , Rodrigo Demarco

An experimental and numerical study of flow velocity fields in a flaming environment, particularly in the high-temperature sooting zone, was conducted in a laminar non-premixed flame. A Yale type burner was employed under flame B conditions. Velocity measurements were performed using Particle Image Velocimetry (PIV), and the OpenPIV software for data treatment. The sooting zone was experimentally characterized using extinction and emission measurements, and were treated to obtain spatially-resolved soot volume fraction and temperature fields. The experimental results were compared with numerical simulations of soot volume fraction, gas temperature, velocity fields using the CoFlame code. A synthetic PIV framework based on the simulations was performed to validate the PIV processing. Experimental results exhibit continuous velocity fields, even in the high-temperature sooting zone, where visibility and the density of the tracer particles are low due to the high temperature gradient, driving particles out of the reaction zone. This was achieved by carefully adjusting the optical arrangement and laser characteristics, to enhance the signal-to-noise ratio and ensure the completeness of the velocity field measurements. The experimental results were in close agreement with numerical predictions for both the inert and reactive flow cases. However, some discrepancies were observed, which were more prominent in the inert case due to the lower gas velocity that exerts less drag on the tracer particles. These discrepancies were reduced by applying a correction to the experimental velocity field along the central streamline, based on Lagrangian modeling of the tracer particles, which considers their mass and diameter.

在层流非预混火焰中，对燃烧环境，特别是高温烟尘区的流速场进行了实验和数值研究。在火焰B条件下使用了耶鲁型燃烧器。速度测量采用粒子图像测速仪（Particle Image Velocity metry， PIV），数据处理采用OpenPIV软件。通过消光和发射测量对烟尘区进行了实验表征，并对其进行了处理，得到了空间分辨的烟尘体积分数和温度场。将实验结果与CoFlame程序对烟尘体积分数、气体温度、速度场的数值模拟结果进行了比较。在仿真的基础上建立了一个综合PIV框架，验证了PIV处理的有效性。实验结果显示出连续的速度场，即使在高温烟尘区，由于高温梯度，示踪颗粒的可见度和密度都很低，导致颗粒被赶出反应区。这是通过仔细调整光学排列和激光特性来实现的，以提高信噪比并确保速度场测量的完整性。在惰性流动和反应流动情况下，实验结果与数值预测非常吻合。然而，观察到一些差异，在惰性情况下，由于气体速度较低，对示踪粒子施加的阻力较小，这种差异更为突出。在拉格朗日示踪粒子模型的基础上，考虑了示踪粒子的质量和直径，通过对沿中心流线的实验速度场进行校正，减少了这些差异。

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引用次数: 0

Aerodynamic characteristics of rounded-corner rectangular cylinders based on wind tunnel model test 基于风洞模型试验的圆角矩形圆柱体气动特性

IF 2.8 2区工程技术 Q2 ENGINEERING, MECHANICAL

Experimental Thermal and Fluid Science

Pub Date : 2025-07-15 DOI: 10.1016/j.expthermflusci.2025.111566

Qun Yang , Chaoyue Zheng , Guankang Ruan , Xiaobing Liu

Through rigid model pressure wind tunnel tests and numerical simulations, the wind pressure for a right-angled rectangular cylinder with an aspect ratio of 2, and for rounded-corner rectangular cylinders with corner radius ratios (R/D) of 0.1, 0.2, 0.3, 0.4, and 0.5 was measured in a uniform flow field. The Reynolds number for the tests was 1.2 × 10⁵, and the wind direction angle (α) ranged from 0° to 90°. A detailed analysis examined the effects of wind direction angle and corner radius ratio on the aerodynamic parameters, including the mean drag/lift coefficients, fluctuating drag/lift coefficients and Strouhal number, and the flow mechanism was explained. The results indicate that at 0° wind direction angle, increasing R/D induces three distinct flow patterns: continuous separation, separation followed by reattachment, and attached flow without separation. Furthermore, two critical wind direction angles, α_cr1 (smaller) and α_cr2 (larger), categorize wind direction angles into three regimes: small (0° < α < α_cr1), intermediate (α_cr1 ≤ α ≤ α_cr2), and large (α_cr2 < α < 90°). The specific ranges of these regimes vary with the cylinder. Notably, α_cr1 exhibits a non-monotonic trend (first decreasing then increasing) with increasing R/D, whereas α_cr2 increases monotonically. Aerodynamic parameters vary more significantly within the small and large wind direction angle regimes than in the intermediate regime. These critical wind direction angles signify transitions in the surface flow state. These findings provide valuable insights for wind-resistant design optimization of rounded-corner rectangular structures in engineering applications.

通过刚性模型压力风洞试验和数值模拟，在均匀流场中测量了长径比为2的直角矩形圆柱体和转角半径比（R/D）分别为0.1、0.2、0.3、0.4和0.5的圆角矩形圆柱体的风压。试验雷诺数为1.2 × 105，风向角（α）范围为0°~ 90°。详细分析了风向角和转角半径比对平均阻力/升力系数、波动阻力/升力系数和斯特劳哈尔数等气动参数的影响，并解释了其流动机理。结果表明：在0°风向角下，增大R/D可产生连续分离、分离后再附着和不分离的附着流动。此外，αcr1（较小）和αcr2（较大）两个临界风向角将风向角分为三种类型：较小(0°<；α& lt;αcr1)、中级(αcr1≤α≤αcr2),和大型(αcr2 & lt;α& lt;90°)。这些制度的具体范围因气缸而异。值得注意的是，αcr1随R/D的增加呈现出先降后升的非单调趋势，而αcr2则呈现单调增加趋势。气动参数在小风向角和大风向角工况下的变化比在中等风向角工况下的变化更显著。这些临界风向角表示地表流动状态的转变。这些研究结果为工程应用中圆角矩形结构的抗风设计优化提供了有价值的见解。

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引用次数: 0

Study on the formation and characteristics of CH4/H2 non-premixed lifted jet flames CH4/H2非预混升力射流火焰的形成及特性研究

IF 2.8 2区工程技术 Q2 ENGINEERING, MECHANICAL

Experimental Thermal and Fluid Science

Pub Date : 2025-07-11 DOI: 10.1016/j.expthermflusci.2025.111561

Hongxu Li , Qiangling Duan , Min Li , Zhiyang Liu , Guanquan Chu , Jinhua Sun , Huahua Xiao

Adding hydrogen to natural gas is a promising way to transport hydrogen fuel, but it also increases the risk of jet fires. This paper experimentally investigated the formation and characteristics of CH₄/H₂ non-premixed lifted jet flames, considering various parameters such as nozzle diameter (d), fuel jet velocity (u), and hydrogen volume fraction (f_v). Digital video and particle image velocimetry were used to obtain flame images and flow field characteristics, respectively. High-speed camera and image intensifier equipped with a 310 nm center wavelength filter were utilized to capture OH* chemiluminescence. The flame lift-off mechanism was elucidated based on the characteristics of the break point. Results indicate local flame quenching at the break point leads to flame lift-off. In the mixing region, for buoyancy-driven jet flames, the flame lift-off height (Δh) decreases as u increases, whereas it increases with u for momentum-driven jet flames. Δh exhibits a linear increase with increasing u in the fully developed region. Furthermore, when a turbulent mixing core forms beneath the base of the lifted flame, Δh experiences a sudden decrease followed by a linear increase with increasing u. It was observed that (Δh/d)(1 − f_v)⁻³ correlates linearly with the 3.76th power of the dimensionless heat release rate,

Q^{*}

. Lastly, an analytical model linking

Q^{*}

, d, and f_v is suggested for predicting the dimensionless flame lift-off height, showing good agreement with experimental data.

向天然气中添加氢是一种很有前途的运输氢燃料的方式，但它也增加了喷气式飞机起火的风险。考虑喷嘴直径(d)、燃料喷射速度(u)、氢气体积分数（fv）等参数，实验研究了CH4/H2非预混升力射流火焰的形成及特性。采用数字视频测速法和粒子图像测速法分别获得火焰图像和流场特征。利用高速摄像机和配有310 nm中心波长滤光片的图像增强器捕捉OH*化学发光。根据断裂点的特点，阐述了火焰的升降机理。结果表明，在断裂点处局部火焰熄灭导致火焰上升。在混合区，浮力驱动射流火焰的火焰升离高度（Δh）随u的增大而减小，动量驱动射流火焰的火焰升离高度随u的增大而增大。Δh在完全发达地区随u的增大呈线性增长。此外，当在升起的火焰底部形成湍流混合核心时，Δh经历了突然下降，然后随着u的增加而线性增加。观察到（Δh/d）(1−fv)−3与无因次放热率Q *的3.76次幂线性相关。最后，提出了一种连接Q *、d和fv的分析模型来预测无因次火焰起飞高度，结果与实验数据吻合良好。

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引用次数: 0

Physics-informed shadowgraph network: an end-to-end self-supervised density field reconstruction method 物理信息阴影网络：端到端自监督密度场重建方法

IF 2.8 2区工程技术 Q2 ENGINEERING, MECHANICAL

Experimental Thermal and Fluid Science

Pub Date : 2025-07-10 DOI: 10.1016/j.expthermflusci.2025.111562

Xutun Wang, Yuchen Zhang, Zidong Li, Haocheng Wen, Bing Wang

This study presents a novel approach for quantificationally reconstructing density fields from shadowgraph images using physics-informed neural networks. The proposed method utilizes the shadowgraph technique visualizing the flow field, enabling reliable quantitative measurement of flow density fields. Compared to traditional methods, which obtain the distribution of physical quality in spatial coordinates case by case, our approach establishes an end-to-end neural network that directly maps shadowgraph images to physical fields. Besides, the model employs a self-supervised learning approach without any labeled data. Experimental validations across hot air jets, thermal plumes, and alcohol burner flames prove the model’s accuracy and universality. This approach offers a non-invasive, real-time surrogate model for flow diagnostics. It is believed that this technique could cover and become a reliable tool in various scientific and engineering disciplines.

本研究提出了一种利用物理信息神经网络从阴影图像定量重建密度场的新方法。该方法利用阴影图技术对流场进行可视化，实现了流密度场的可靠定量测量。与传统方法在空间坐标中逐例获取物理质量分布相比，我们的方法建立了一个端到端的神经网络，直接将阴影图像映射到物理场。此外，该模型采用自监督学习方法，不需要任何标记数据。热空气射流、热羽流和酒精燃烧器火焰的实验验证证明了该模型的准确性和通用性。这种方法为流体诊断提供了一种非侵入性的实时代理模型。相信该技术可以覆盖并成为各种科学和工程学科的可靠工具。

引用次数: 0

Experimental study of the characteristics and stability of liquid film formed by impinging of water jets on a large vertical plate 大型垂直板上水射流冲击形成液膜特性及稳定性的实验研究

IF 2.8 2区工程技术 Q2 ENGINEERING, MECHANICAL

Experimental Thermal and Fluid Science

Pub Date : 2025-07-08 DOI: 10.1016/j.expthermflusci.2025.111563

Feng Zhou , Weichen Sun , Qiang Chen , Haifeng Liu , Xiaobo Shen

This paper presents an experimental investigation of the liquid film resulting from jet impingement on a large-scale flat plate. A high-speed camera was used to capture direct footage of the liquid film, which was then analyzed using image processing techniques. The study focused on determining the thickness of the liquid film at various positions along the axial direction and examining the distribution and fluctuation characteristics of the falling liquid film under Reynolds number ranging from 4250 to 8500. Experiments were conducted at different angles of incidence to investigate the influence of the incidence angle on the thickness of the liquid film formed by the collision. The experimental results show that the development of liquid film thickness with increasing axial distance is divided into three stages. As the incident Reynolds number increases, both the average thickness and the degree of fluctuation of the liquid film increase, while the growth rate of the thickness decreases. Furthermore, it is evident that the surface of the liquid film will be disrupted during the flow process, and two modes of disruption have been distinguished.

本文对大型平板上射流撞击形成的液膜进行了实验研究。使用高速摄像机捕捉液体胶片的直接镜头，然后使用图像处理技术对其进行分析。研究重点确定了沿轴向不同位置液膜的厚度，考察了雷诺数在4250 ~ 8500范围内液膜下落的分布和波动特性。在不同入射角下进行了实验，研究了不同入射角对碰撞形成液膜厚度的影响。实验结果表明，液膜厚度随轴向距离的增加可分为三个阶段。随着入射雷诺数的增加，液膜的平均厚度和波动程度均增大，而厚度的增长率减小。此外，在流动过程中，液膜表面明显会被破坏，并区分出两种破坏模式。

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引用次数: 0

Time-resolved PIV measurements of an unsteady viscous oil flow in a centrifugal pump 离心泵内非定常粘性油流的时间分辨PIV测量

IF 2.8 2区工程技术 Q2 ENGINEERING, MECHANICAL

Experimental Thermal and Fluid Science

Pub Date : 2025-07-08 DOI: 10.1016/j.expthermflusci.2025.111558

Rodolfo M. Perissinotto , William D.P. Fonseca , Rafael F.L. Cerqueira , Natan A.V. Bulgarelli , William Monte Verde , Erick M. Franklin , Marcelo S. Castro

Centrifugal pumps are essential for many human activities, accounting for a considerable portion of the global electricity consumption. However, despite decades of study, the flow within the pump’s impeller and its effects on the performance are far from being fully understood, particularly when the flow involves fluids more viscous than water. In this context, this paper reports experiments using time-resolved particle image velocimetry (TR-PIV) for investigating the flow of a 14-cP-viscosity mineral oil in a transparent pump with radial impeller. We found that: (i) at low flow rates, the positions of vortices depend on the fluid properties; (ii) at higher flow rates, the oil flows aligned in the radial direction, while the water flows following closely the blade curvature; (iii) the velocity profiles for the oil are approximately parabolic, whereas those for water are flatter; (iv) the average deflection angle of the velocity vectors relative to the blade curvature changes significantly with viscosity; (v) contrary to common expectation, the turbulent kinetic energy is up to four times higher for oil than for water; (vi) vortices are periodically formed and dissipated with a frequency proportional to the rotational speed. Our results provide new insights into the flow of viscous fluids in pumps, with valuable information for their design and installation.

离心泵是许多人类活动必不可少的，占全球电力消耗的相当一部分。然而，尽管经过了几十年的研究，人们仍远未完全了解泵叶轮内的流动及其对性能的影响，特别是当流动涉及比水更粘稠的流体时。在此背景下，本文报道了使用时间分辨粒子图像测速（TR-PIV）研究14cp粘度矿物油在径向叶轮透明泵中的流动的实验。我们发现：(1)在低流速下，涡旋的位置与流体性质有关；（ii）在高流速下，油流沿径向排列，而水流则沿叶片弯曲方向流动；(3)油的速度分布近似为抛物线，而水的速度分布较为平缓；（iv）速度矢量相对于叶片曲率的平均偏转角随黏度变化显著；(5)与一般预期相反，油的湍流动能比水高4倍；(6)涡旋周期性地形成并以与转速成正比的频率消散。我们的研究结果为泵中粘性流体的流动提供了新的见解，为泵的设计和安装提供了有价值的信息。

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