Flow Measurement and Instrumentation最新文献_第4页

Statistical simulator for synthesizing disturbance waves in downward vertical annular flow 用于合成垂向环形流扰动波的统计模拟器

IF 2.7 3区工程技术 Q2 ENGINEERING, MECHANICAL

Flow Measurement and Instrumentation

Pub Date : 2026-01-06 DOI: 10.1016/j.flowmeasinst.2026.103190

Ana Luiza B. Santana , Natan Schieck Reginaldo , Moisés A. Marcelino Neto , Rigoberto E.M. Morales , Marco José da Silva , Eduardo Nunes dos Santos

Annular flow is a gas-liquid flow regime commonly encountered in industrial applications, such as those in nuclear power and oil and gas production. While upward configurations have received substantial attention, detailed investigations of downward vertical annular flow remain comparatively limited. This study presents a statistical synthesis simulator capable of generating representative annular flow time series using only supervisory process parameters typically available in industrial environments, including pipe diameter, volumetric flow rates, and fluid properties (density and viscosity). Experiments were performed in two test sections with internal pipe diameters of 26 mm and 50 mm, where film thickness time series were recorded using a non-intrusive, high-speed conductance sensor. The acquired data were analyzed to extract key characteristics of the disturbance waves, including frequency, amplitude, velocity, and wave shape, which were then used to formulate empirical correlations governing the generation of synthetic unit waves. Using the combined 26-mm and 50-mm databases, the fitted correlations achieved R² values of 0.91–0.99 for the main unit-wave geometrical parameters. These correlations were incorporated into the simulator to construct the synthetic film-thickness time series, from which the mean liquid fraction is computed and compared to experimental data. The results fall predominantly within the ±30 % band, with overall errors of approximately MAPE ≈21 %.

环空流动是工业应用中常见的气液流动形式，例如核电和油气生产。虽然向上的环空流动得到了大量关注，但对向下垂直环空流动的详细研究仍然相对有限。本研究提出了一种统计合成模拟器，能够仅使用工业环境中通常可用的监控过程参数（包括管径、体积流速和流体性质（密度和粘度））生成具有代表性的环空流动时间序列。实验在内径为26 mm和50 mm的两个测试段中进行，其中使用非侵入式高速电导传感器记录膜厚时间序列。对采集到的数据进行分析，提取干扰波的关键特征，包括频率、振幅、速度和波形，然后使用这些特征来制定控制合成单位波产生的经验相关性。在26-mm和50-mm数据库中，主要单位波几何参数的拟合相关R2为0.91-0.99。将这些相关性纳入模拟器，构建合成膜厚度时间序列，从中计算平均液体分数并与实验数据进行比较。结果主要落在±30%的范围内，总体误差约为MAPE≈21%。

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引用次数: 0

RivP-RAFT: A patch-based RAFT model for efficient river surface velocity estimation using images RivP-RAFT：一种基于补丁的RAFT模型，用于利用图像有效地估计河流表面速度

IF 2.7 3区工程技术 Q2 ENGINEERING, MECHANICAL

Flow Measurement and Instrumentation

Pub Date : 2026-01-06 DOI: 10.1016/j.flowmeasinst.2026.103193

Pouria Moradi , Neda Faraji , Masoumeh Hashemi , Javad Ataei

Monitoring river velocity and discharge is crucial for effective water resource management and flood prediction, among which image-based velocimetry techniques stand out for their cost-effectiveness and non-invasive nature. However, image-based methods using deep optical flow neural networks encounter two main challenges. The first challenge is the need for datasets containing flow labels to effectively train the networks, which is not easily obtainable in riverine areas. The second challenge pertains to the need for powerful computational resources, as these networks achieve optical flow estimations at the pixel-level, rendering them unsuitable for real-time flood warning systems. In this paper, we introduce a new framework for measuring river velocity, built on the original architecture of the Recurrent All-pairs Field Transforms (RAFT) network. Our approach improves the performance of the pre-trained RAFT by utilizing a fine-tuning method that incorporates the RealFlow technique for generating labeled data from rivers, followed by well-designed post-processing steps aimed at removing outliers of velocity estimates. We also present an innovative patch-based training framework designed to improve the patch-based RAFT network’s (P-RAFT) efficacy by employing fine-tuning strategy. The fine-tuned patch-based RAFT (RivP-RAFT) provides rapid and accurate river discharge estimation at designated cross-sections of the river, crucial for flood warning applications. On Colorado’s Blue River, it achieved 26.8 m

^{3}

/s with a relative error 1.5%, significantly outperforming PIV (18.5%), STIV (9.9%), OTV (8.1%), and dense RAFT (12.2%). Moreover, RivP-RAFT operates at 0.39 frames per second, offering a substantial computational advantage over dense RAFT’s 0.03 frames per second.

监测河流流速和流量对于有效的水资源管理和洪水预测至关重要，其中基于图像的测速技术以其成本效益和非侵入性而脱颖而出。然而，使用深度光流神经网络的基于图像的方法面临两个主要挑战。第一个挑战是需要包含流量标签的数据集来有效地训练网络，这在河流地区不容易获得。第二个挑战是需要强大的计算资源，因为这些网络在像素级实现光流估计，使得它们不适合实时洪水预警系统。在本文中，我们引入了一种新的测量河流流速的框架，该框架建立在循环全对场变换（RAFT）网络的原始架构之上。我们的方法通过利用微调方法来提高预训练RAFT的性能，该方法结合了RealFlow技术，用于从河流中生成标记数据，然后是精心设计的后处理步骤，旨在消除速度估计的异常值。我们还提出了一个创新的基于补丁的训练框架，旨在通过采用微调策略来提高基于补丁的RAFT网络（P-RAFT）的有效性。基于微调补丁的RAFT （RivP-RAFT）在指定的河流断面上提供快速准确的河流流量估算，这对洪水预警应用至关重要。在科罗拉多州的蓝河上，它达到了26.8 m3/s，相对误差为1.5%，显著优于PIV（18.5%）、STIV（9.9%）、OTV（8.1%）和dense RAFT（12.2%）。此外，RivP-RAFT的运行速度为每秒0.39帧，比致密RAFT的每秒0.03帧提供了实质性的计算优势。

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引用次数: 0

Investigation on the influence of mud viscosity variation on flow loss in a multistage axial lifting pump based on the entropy production method 基于熵产法的多级轴向举升泵内泥浆粘度变化对流动损失影响研究

IF 2.7 3区工程技术 Q2 ENGINEERING, MECHANICAL

Flow Measurement and Instrumentation

Pub Date : 2026-01-03 DOI: 10.1016/j.flowmeasinst.2026.103189

Yan Gong , Pan Xiang , Wen Zeng , Bohan Hu , Yingjie Hu

In drilling operations, the lifting pump plays a crucial role in circulating drilling fluid containing cuttings. This study focuses on analyzing hydraulic losses in the ultra-small-diameter multistage axial flow pump cascade, employing entropy production theory to conduct an in-depth investigation of the axial-flow pump impeller and guide vane cascade. During the research, a three-stage cross-blade numerical computational model for axial flow pumps was developed. Utilizing CFD methods, the flow field characteristics within the cascade under design flow conditions for multi-viscosity drilling fluids are simulated. By introducing entropy production theory, this paper systematically calculates and analyzes various types of entropy production rates and entropy output values, thereby revealing the root causes of hydraulic losses at the level of fluid mechanics mechanisms. Under design conditions, the entropy output of the guide vane cascade is generally higher than that of the impeller cascade, indicating that hydraulic losses in the guide vane region are more significant. Further analysis reveals that viscosity adjustment has a more pronounced effect on time-averaged entropy production. The high entropy production regions of the impeller are primarily concentrated near the suction side, while those of the guide vanes are mainly located near the pressure side.

在钻井作业中，举升泵对含岩屑钻井液的循环起着至关重要的作用。本研究重点分析了超小口径多级轴流泵叶栅的水力损失，运用熵产理论对轴流泵叶轮和导叶叶栅进行了深入研究。在研究过程中，建立了轴流泵的三级交叉叶片数值计算模型。利用CFD方法，模拟了多粘度钻井液在设计流动条件下的叶栅内流场特性。本文通过引入熵产理论，系统地计算和分析了各类熵产率和熵产出值，从而在流体力学机制层面揭示了水力损失的根本原因。在设计条件下，导叶叶栅的熵输出一般高于叶轮叶栅，说明导叶区域的水力损失更为显著。进一步分析表明，粘度调整对时间平均熵产生的影响更为显著。叶轮的高熵产生区主要集中在吸力侧附近，导叶的高熵产生区主要集中在压力侧附近。

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引用次数: 0

Torque fluctuation and transmission efficiency analysis of key transmission parts of curve-face gear plunger pump 曲线齿轮柱塞泵关键传动部件转矩波动及传动效率分析

IF 2.7 3区工程技术 Q2 ENGINEERING, MECHANICAL

Flow Measurement and Instrumentation

Pub Date : 2026-01-02 DOI: 10.1016/j.flowmeasinst.2025.103185

Fuqiang Wang , Xudong Yang , Changbin Dong, Ru Kang

To address the lack of quantitative understanding of torque fluctuation and transmission efficiency in the key transmission components of curve-face gear (CFG) plunger pump, this paper investigates the CFG composite mechanism that replaces the traditional swash plate mechanism and innovatively proposes a unified analysis framework combining torque fluctuation modelling with transmission efficiency evaluation. A torque fluctuation model of the CFG composite mechanism is established based on the spatial pitch curve, and the variation laws of angular acceleration and input torque under different structural and operating parameters are analyzed. A three-dimensional finite element contact model with an equivalent axial spring is constructed to obtain the actual torque fluctuation of the CFG, and the instantaneous and average transmission efficiency and their sensitivity to main parameters are evaluated. The results show that the tooth number, modulus and pitch-curve extreme value of the driving gear are inversely related to the amplitude of angular-acceleration fluctuation, while the order of the CFG affects both the period and amplitude of the fluctuation. The torques of both gears fluctuate periodically, and the torque fluctuation amplitude increases with the tooth number and modulus of the driving gear, the pitch-curve extreme value and the CFG order. The transmission efficiency over one meshing cycle presents obvious periodic variations, and the efficiency at the wave crest is significantly lower than that at the wave trough. Under the reference condition, the average transmission efficiency is about 83.25 %, and it increases with load torque but decreases with input speed.

针对目前对曲线齿轮柱塞泵关键传动部件转矩波动和传动效率缺乏定量认识的问题，对取代传统斜盘机构的曲线齿轮柱塞泵复合机构进行了研究，创新性地提出了转矩波动建模与传动效率评价相结合的统一分析框架。基于空间节距曲线建立了CFG复合机构的转矩波动模型，分析了不同结构参数和工作参数下角加速度和输入转矩的变化规律。建立了具有等效轴向弹簧的三维有限元接触模型，获得了CFG的实际转矩波动，并评估了瞬时和平均传动效率及其对主要参数的敏感性。结果表明：驱动齿轮的齿数、模量和俯仰曲线极值与角加速度波动幅值呈负相关，而CFG的顺序对波动周期和波动幅值均有影响。两齿轮转矩周期性波动，转矩波动幅度随主动齿轮齿数、齿模、节距曲线极值和CFG阶数的增大而增大。一个啮合周期内的传输效率呈现明显的周期性变化，波峰处的传输效率明显低于波谷处的传输效率。参考工况下，平均传动效率约为83.25%，随负载转矩增大而增大，随输入转速减小而减小。

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引用次数: 0

Optimized design and experimental study of an ultra-high-pressure air linear flow regulation valve 超高压空气线性流量调节阀的优化设计与实验研究

IF 2.7 3区工程技术 Q2 ENGINEERING, MECHANICAL

Flow Measurement and Instrumentation

Pub Date : 2026-01-01 DOI: 10.1016/j.flowmeasinst.2025.103182

LongLong Gao, Yue Shi, Baoren Li, JiaCheng Li

To address the poor linearity between valve core displacement and valve mass flow in conventional air flow control valves, which limits flow regulation accuracy, this study proposes an ultra-high-pressure air linear flow regulation valve (UHPALFRV) designed using a dual-cubic contraction profile, a Laval nozzle, and a quadratic envelope. Multiple numerical models of Laval-nozzle valve seats were established, and their flow characteristics were evaluated via pressure distribution, turbulent kinetic energy (TKE), and Mach number to identify the valve seat geometry most conducive to gas flow. A mathematical model linking valve core displacement to effective flow area was formulated for the novel linear regulation unit, and key parameters were optimized using an improved particle swarm optimization algorithm integrating chaotic mapping, golden sine perturbation, Cauchy dynamic perturbation, and an elite selection strategy, thereby achieving highly linear flow modulation. A high-pressure air valve test platform was constructed, and flow linearity tests were performed. The results indicate that, compared with the other three configurations, the valve seat employing a dual-cubic contraction profile exhibits a more uniform pressure gradient and higher consistency. The mean absolute error (MAE) and root-mean-square error (RMSE) of the pressure distribution on the symmetry plane are 114238.6 and 297583.9, respectively—the lowest among the four groups—and the domain-averaged turbulent kinetic energy (TKE) decreases by approximately 12.1 %. Building on this, the optimized spool–seat combination achieves a maximum TKE reduction of about 38.8 %, while the peak Mach number at the throat increases by roughly 4.26 %. The maximum relative discrepancy between experiments and CFD is around 4.43 %. After optimization, the linearity of the displacement–mass flow rate relationship reaches 99.734 %, with a sum of squared errors (SSE) of 0.00292. These findings substantiate the effectiveness and high-precision characteristics of the proposed structure and optimization methodology.

为了解决传统空气流量控制阀阀芯位移和阀质量流量之间线性度差的问题，限制了流量调节精度，本研究提出了一种采用双立方收缩型线、拉瓦尔喷嘴和二次包线设计的超高压空气线性流量调节阀（UHPALFRV）。建立了拉瓦尔喷嘴阀座的多种数值模型，通过压力分布、湍流动能（TKE）和马赫数对其流动特性进行了评价，确定了最有利于气体流动的阀座几何形状。针对新型线性调节单元，建立了阀芯位移与有效通流面积的数学模型，并采用结合混沌映射、金正弦摄动、柯西动态摄动和精英选择策略的改进粒子群优化算法对关键参数进行优化，实现了高度线性的流量调节。搭建了高压气阀试验平台，进行了流量线性度试验。结果表明，与其他三种结构相比，双立方收缩型阀座具有更均匀的压力梯度和更高的一致性。对称面压力分布的平均绝对误差（MAE）和均方根误差（RMSE）分别为114238.6和297583.9，是四组中最低的，区域平均湍流动能（TKE）降低了约12.1%。在此基础上，优化后的阀芯-阀座组合最大TKE减小约38.8%，喉部峰值马赫数增加约4.26%。实验与CFD的最大相对误差约为4.43%。优化后的排量-质量流量关系线性度达到99.734%，平方误差和（SSE）为0.00292。这些发现证实了所提出的结构和优化方法的有效性和高精度特性。

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引用次数: 0

Comparative CFD study on flow behavior and performance enhancement of grooved NACA 0012 and NACA 4415 airfoils 开槽NACA 0012和NACA 4415翼型流动特性及性能增强的CFD对比研究

IF 2.7 3区工程技术 Q2 ENGINEERING, MECHANICAL

Flow Measurement and Instrumentation

Pub Date : 2026-01-01 DOI: 10.1016/j.flowmeasinst.2025.103186

Rubiat Mustak, Mohammad Mashud

This study provides a comparative assessment of groove-induced passive flow control on symmetric and cambered NACA airfoils using boundary layer based groove placement. The influence of rectangular surface grooves on aerodynamic performance is numerically investigated. Surface groove that delays the flow separation of airfoils, creating recirculating vortices. These vortices, by exchanging momentum between the high-speed outer region and slowing down near wall region, re-energize the boundary layer. To alter the performance of symmetric NACA 0012 and cambered NACA 4415 airfoils, rectangular surface grooves were placed at the mid-chord length of the respective airfoils. Two-dimensional steady simulations of turbulent flow are carried out at a Reynolds number of Re = 2.88 × 10⁵ using the finite volume method in ANSYS Fluent (Version 2024 R1). Turbulence effects are modeled using the SST

(k - ω)

model. A structured C-type computational domain is employed, and the numerical results are validated with existing experimental data. Flow behavior was analyzed using contours, streamlines, and velocity vectors. The results show that, the cambered NACA 4415 airfoil gains more benefit from the rectangular groove than the symmetric NACA 0012 airfoil. The modified NACA 4415 airfoil exhibits a larger stall delay (2° vs. 1°) and greater lift enhancement (+14.20 % at 18° AOA vs. +10.70 % at 16° AOA). It also achieves higher aerodynamic efficiency (+12.40 % at 8° AOA vs. 10.38 % at 6° AOA) with greater drag reduction (−15.48 % vs. −9.73 %). In addition, the NACA 4415 airfoil attains a higher maximum lift-to-drag ratio (49.90) compared to the NACA 0012 airfoil (43.23).

这项研究提供了一个比较评估的沟槽诱导被动流动控制对称和弯曲的NACA翼型采用边界层为基础的沟槽布置。数值研究了矩形表面沟槽对气动性能的影响。表面沟槽，延迟气流分离的翼型，创造再循环涡旋。这些涡旋通过在高速的外区和慢速的近壁区之间交换动量，给边界层重新注入能量。为了改变对称NACA 0012和弯曲NACA 4415翼型的性能，在各自翼型的中弦长处放置了矩形表面凹槽。在ANSYS Fluent （Version 2024 R1）软件中，采用有限体积法对雷诺数Re = 2.88 × 105时紊流进行了二维定常模拟。湍流效应采用海温（k−ω）模式模拟。采用结构化的c型计算域，数值结果与已有的实验数据进行了验证。利用等高线、流线和速度矢量分析流动行为。结果表明，与对称的NACA 0012翼型相比，弯曲的NACA 4415翼型从矩形槽中获得了更多的收益。改进的NACA 4415翼型表现出较大的失速延迟（2°对1°）和更大的升力增强（+ 14.20%在18°AOA对+ 10.70%在16°AOA）。它还具有更高的气动效率（8°AOA时为+ 12.40%，6°AOA时为10.38%）和更大的阻力减小（- 15.48%，6°AOA时为- 9.73%）。此外，与NACA 0012翼型（43.23）相比，NACA 4415翼型获得了更高的最大升阻比（49.90）。

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引用次数: 0

Experimental and numerical investigation of vibration–oil flow coupling effects on the heavy gas action of QJ1-80 and BF-80 type gas relays QJ1-80型和BF-80型气体继电器重气动作振动-油流耦合效应的实验与数值研究

IF 2.7 3区工程技术 Q2 ENGINEERING, MECHANICAL

Flow Measurement and Instrumentation

Pub Date : 2025-12-31 DOI: 10.1016/j.flowmeasinst.2025.103183

Wei Liu , Shuting Wan , Siyu Tian , Zhihan Li , Bing Xue , Chengxiang Liu , Zhuoyan Zhong , Jianwei Cheng , Zehua Wu

The heavy gas maloperation of gas relays seriously endangers the safe operation of transformers, yet the characteristic differences between the QJ1-80 type (spring-baffle mechanism) and BF-80 type (magnet-baffle mechanism) under vibration-transient oil flow coupled excitation have not been systematically studied. To fill this gap, this study conducted a comparative investigation of the characteristics of the two types of gas relays through theoretical modeling, coupled excitation tests, and fluid-solid coupling simulations using large-eddy simulation (LES). Results show that: under single oil flow excitation, the QJ1-80 type has a critical pressure of 0.120 MPa and a setting flow velocity of 0.910 m/s, while the BF-80 type has a critical pressure of 0.110 MPa and a setting flow velocity of 0.721 m/s; after the introduction of vibration, the heavy gas action flow velocity of the BF-80 type decreased to 0.643 m/s (a decrease of 10.7 %), and the QJ1-80 type failed to trigger the heavy gas action. Resistance torque characteristics determined the response differences: the former had better anti-interference performance, while the latter had higher sensitivity. The empirical formula shows that the reduction amplitude of the BF-80 type is 3.8 times that of the QJ1-80 type, and the errors between experiments and simulations are both less than 1.71 %. This study clarifies the coupled response laws of the two types, provides a scientific basis for device selection and setting value optimization, and has significant engineering value for improving the reliability of power system protection.

气体继电器的重气体误动严重危及变压器的安全运行，而QJ1-80型（弹簧-挡板机构）与BF-80型（磁铁-挡板机构）在振动-瞬态油流耦合激励下的特性差异还没有系统的研究。为了填补这一空白，本研究通过理论建模、耦合激励试验和采用大涡模拟（LES）的流固耦合模拟，对两种气体继电器的特性进行了对比研究。结果表明：在单次油流激励下，QJ1-80型临界压力为0.120 MPa，设定流速为0.910 m/s， BF-80型临界压力为0.110 MPa，设定流速为0.721 m/s；引入振动后，BF-80型重气作用流速降至0.643 m/s（下降10.7%），QJ1-80型重气作用未能触发。电阻转矩特性决定了响应差异：前者具有较好的抗干扰性能，而后者具有较高的灵敏度。经验公式表明，BF-80型的减振幅度是QJ1-80型的3.8倍，实验与仿真误差均小于1.71%。本研究阐明了两种类型的耦合响应规律，为设备选型和整定值优化提供了科学依据，对提高电力系统保护可靠性具有重要的工程价值。

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引用次数: 0

EDITORIAL: Special issue on advances in multiphase flow measurement and sensing technology 社论：多相流测量和传感技术进展特刊

IF 2.7 3区工程技术 Q2 ENGINEERING, MECHANICAL

Flow Measurement and Instrumentation

Pub Date : 2025-12-31 DOI: 10.1016/j.flowmeasinst.2025.103184

Haigang Wang , Laurent Babout , Yi Li , Wu Zhou

引用次数: 0

Dynamic response and output characteristics of high-speed on/off valves based on structural optimization and load force characterization 基于结构优化和负载力表征的高速开关阀动态响应及输出特性

IF 2.7 3区工程技术 Q2 ENGINEERING, MECHANICAL

Flow Measurement and Instrumentation

Pub Date : 2025-12-30 DOI: 10.1016/j.flowmeasinst.2025.103181

Zibo Chen , Rulu Wei , Zuzhi Tian , Fangwei Xie , Nan Chen

Addressing the challenges in accurately predicting the frequency response and flow output of high-speed on/off valves (HSVs) in digital hydraulic systems, this study investigates their dynamic response and output characteristics through integrated electromechanical-hydraulic co-simulation and experimental testing. A dynamic model of the HSV, including its load, is established. An analysis method for dynamic performance, based on the load force function, is proposed to examine the valve's opening and closing behavior and the resulting flow characteristics. Structural parameters are subsequently optimized. Results show that the optimized valve exhibits significantly reduced opening and closing times, and its cutoff frequency increases from 37 Hz to 53 Hz. Additionally, it is found that an increase in operating frequency narrows the linear flow modulation range and reduces output flow, while a decrease in pressure differential leads to a parabolic decay in output. Experimental results validate the simulation, demonstrating that the prototype achieves a linear modulation range of 30 %–70 % at 40 Hz and a maximum operating frequency of 60 Hz. This research establishes an integrated electromagnetic-mechanical-hydraulic load force model and proposes a structural optimization framework based on load force characterization. This provides a new co-design approach for the synergistic optimization and precise control of HSVs.

针对数字液压系统中高速开关阀（hsv）的频率响应和流量输出难以准确预测的问题，通过机电液联合仿真和实验测试，研究了高速开关阀的动态响应和输出特性。建立了包括载荷在内的HSV的动力学模型。提出了一种基于载荷力函数的动态性能分析方法，分析了阀门的启闭特性及其产生的流量特性。随后对结构参数进行了优化。结果表明，优化后的阀门开启和关闭次数显著减少，截止频率从37 Hz提高到53 Hz。此外，发现工作频率的增加缩小了线性流量调制范围并减小了输出流量，而压差的减小导致输出呈抛物线衰减。实验结果验证了仿真结果，表明样机在40 Hz时实现了30% - 70%的线性调制范围，最大工作频率为60 Hz。建立了电磁-机械-液压综合载荷力模型，提出了基于载荷力表征的结构优化框架。这为hsv的协同优化和精确控制提供了一种新的协同设计方法。

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引用次数: 0

Calculation of drag coefficient and friction factor of non-submerged rigid vegetation in symmetric compound channel, using direct measurement method 采用直接测量法计算对称复合河道非淹没刚性植被的阻力系数和摩擦系数

IF 2.7 3区工程技术 Q2 ENGINEERING, MECHANICAL

Flow Measurement and Instrumentation

Pub Date : 2025-12-29 DOI: 10.1016/j.flowmeasinst.2025.103179

Foad Maturi , Mehdi Behdarvandi Askar

Given that the most basic issue in the study of drag coefficient is the correct and accurate measurement of force, so the use of a method that can directly measure the force of flow is very important because it can provide a more realistic analysis of drag coefficient. Also, the results obtained from this method are compared with the results obtained from other methods.This research has calculated the drag coefficient and friction factor using the direct measurement method and physical modeling in a hydraulic knife-edge flume, which is a particular type of flume capable of directly measuring the flow force. In this study, five vegetation diameters, 20, 25, 30, 40, and 50 mm, as well as two types of ordered and non-ordered arrangement, and three vegetation positions in floodplains, main channel and simultaneously vegetation in main channel and floodplain, considering five inline spacing, and three Cross line spacing between vegetation, which included a total of 451 different experiments, were examined. In this paper, the

φ

value is between 0.0017 and 0.31, and the vegetation's Reynolds number is in the range 3512–29213. The results revealed that the method and calculations implemented in the field of drag coefficient are suitably similar to the drag coefficient obtained from the force balance equation; moreover to calculate drag coefficient and friction factor in the examined scope,

C_{D} = α_{1} {(λ^{*})}^{α_{2}}

and

f_{T} = β_{1} (Ln (λ^{*}) + β_{2}

were achieved based on the vegetation parameter

(λ^{*})

. The coefficients of

α_{1} . α_{2} . β_{1} a n d β_{2}

considering the experiments and different position and arrangement of vegetation were presented.

考虑到阻力系数研究中最基本的问题是正确准确的力的测量，因此采用一种可以直接测量流动力的方法是非常重要的，因为它可以提供更真实的阻力系数分析。并与其他方法的计算结果进行了比较。本研究采用直接测量法和物理建模的方法计算了水力刃形水槽的阻力系数和摩擦系数，这是一种能够直接测量流力的特殊水槽。本研究选取20、25、30、40和50 mm 5种植被直径，有序和无序两种类型，以及河漫滩、主河道和主河道与河漫滩同时存在的3种植被位置，考虑5种植被间的行距和3种植被间的交叉间距，共进行了451次不同的实验。本文中φ值在0.0017 ~ 0.31之间，植被的雷诺数在3512 ~ 29213之间。结果表明，所采用的阻力系数计算方法与由力平衡方程得到的阻力系数有较好的相似性；为计算检查范围内的阻力系数和摩擦系数，基于植被参数（λ∗）得到CD=α1(λ∗)α2和fT=β1(Ln(λ∗)+β2。α1 α2的系数。β1和β2考虑了不同的植被位置和排列方式。

{"title":"Calculation of drag coefficient and friction factor of non-submerged rigid vegetation in symmetric compound channel, using direct measurement method","authors":"Foad Maturi , Mehdi Behdarvandi Askar","doi":"10.1016/j.flowmeasinst.2025.103179","DOIUrl":"10.1016/j.flowmeasinst.2025.103179","url":null,"abstract":"<div><div>Given that the most basic issue in the study of drag coefficient is the correct and accurate measurement of force, so the use of a method that can directly measure the force of flow is very important because it can provide a more realistic analysis of drag coefficient. Also, the results obtained from this method are compared with the results obtained from other methods.This research has calculated the drag coefficient and friction factor using the direct measurement method and physical modeling in a hydraulic knife-edge flume, which is a particular type of flume capable of directly measuring the flow force. In this study, five vegetation diameters, 20, 25, 30, 40, and 50 mm, as well as two types of ordered and non-ordered arrangement, and three vegetation positions in floodplains, main channel and simultaneously vegetation in main channel and floodplain, considering five inline spacing, and three Cross line spacing between vegetation, which included a total of 451 different experiments, were examined. In this paper, the <span><math><mrow><mi>φ</mi></mrow></math></span> value is between 0.0017 and 0.31, and the vegetation's Reynolds number is in the range 3512–29213. The results revealed that the method and calculations implemented in the field of drag coefficient are suitably similar to the drag coefficient obtained from the force balance equation; moreover to calculate drag coefficient and friction factor in the examined scope, <span><math><mrow><msub><mi>C</mi><mi>D</mi></msub><mo>=</mo><msub><mi>α</mi><mn>1</mn></msub><msup><mrow><mo>(</mo><msup><mi>λ</mi><mo>∗</mo></msup><mo>)</mo></mrow><msub><mi>α</mi><mn>2</mn></msub></msup></mrow></math></span> and <span><math><mrow><msub><mi>f</mi><mi>T</mi></msub><mo>=</mo><msub><mi>β</mi><mn>1</mn></msub><mo>(</mo><mi>Ln</mi><mrow><mo>(</mo><msup><mi>λ</mi><mo>∗</mo></msup><mo>)</mo></mrow><mo>+</mo><msub><mi>β</mi><mn>2</mn></msub></mrow></math></span> were achieved based on the vegetation parameter <span><math><mrow><mo>(</mo><msup><mi>λ</mi><mo>∗</mo></msup><mo>)</mo></mrow></math></span>. The coefficients of <span><math><mrow><msub><mi>α</mi><mn>1</mn></msub><mo>.</mo><msub><mi>α</mi><mn>2</mn></msub><mo>.</mo><msub><mi>β</mi><mn>1</mn></msub><mspace></mspace><mi>a</mi><mi>n</mi><mi>d</mi><mspace></mspace><msub><mi>β</mi><mn>2</mn></msub></mrow></math></span> considering the experiments and different position and arrangement of vegetation were presented.</div></div>","PeriodicalId":50440,"journal":{"name":"Flow Measurement and Instrumentation","volume":"108 ","pages":"Article 103179"},"PeriodicalIF":2.7,"publicationDate":"2025-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145883508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

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