Experiments in Fluids最新文献_第9页

How different are conventional and biofuel sprays applied to aviation? An infodynamic comparative analysis 传统喷雾剂和生物燃料喷雾剂在航空领域的应用有何不同？信息动态比较分析

IF 2.5 3区工程技术

Experiments in Fluids Pub Date : 2025-05-27 DOI: 10.1007/s00348-025-04042-9

Inês A. S. Ferrão, Miguel R. O. Panão, Miguel A. A. Mendes, Ana S. H. O. Moita, André R. R. Silva

{"title":"How different are conventional and biofuel sprays applied to aviation? An infodynamic comparative analysis","authors":"Inês A. S. Ferrão, Miguel R. O. Panão, Miguel A. A. Mendes, Ana S. H. O. Moita, André R. R. Silva","doi":"10.1007/s00348-025-04042-9","DOIUrl":"10.1007/s00348-025-04042-9","url":null,"abstract":"<div><p>The transition from fossil to sustainable and alternative fuels is imperative to address environmental concerns and meet energy requirements. Thus, the implementation of alternative fuels requires a deeper investigation of spray behavior. This study explores conventional jet fuel (Jet A-1) and hydrotreated vegetable oil (HVO) in terms of breakup length and spray dynamics over a wide range of operating conditions. The normalized mean breakup length was measured, and an empirical correlation was developed based on the experimental data. Focusing on the droplet sizes in fuel sprays, which are critical for optimizing combustion, an informational perspective for comparative analysis was explored. The terms informature, infotropy, and infosensor were introduced to quantify and capture the non-deterministic nature of physical systems. The results revealed similar drop size distributions for HVO and Jet A-1, with the Gamma function effectively characterizing the distributions. Both fuels exhibit spray evolution toward higher complexity states, emphasizing the role of aerodynamic forces and minimum development distance in atomization. The new lexicon of infodynamics views sprays as networks of information flow, with infotropy indicating that both fuels produce sprays with similar degrees of transformation. HVO is endorsed as a viable alternative with broader implications for sustainable aviation solutions and understanding complex engineering processes. </p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"66 6","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00348-025-04042-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145169670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Forward projected background oriented Schlieren for study of sparks in internal combustion engines 用于内燃机火花研究的正投影背景定向纹影

IF 2.5 3区工程技术

Experiments in Fluids Pub Date : 2025-05-27 DOI: 10.1007/s00348-025-04041-w

Saraschandran Kottakalam, Gregor Rottenkolber, Christian Trapp

{"title":"Forward projected background oriented Schlieren for study of sparks in internal combustion engines","authors":"Saraschandran Kottakalam, Gregor Rottenkolber, Christian Trapp","doi":"10.1007/s00348-025-04041-w","DOIUrl":"10.1007/s00348-025-04041-w","url":null,"abstract":"<div><p>The use of renewable fuels, such as hydrogen, in internal combustion engines necessitates the development of innovative combustion strategies, which in turn demand a profound comprehension of the underlying ignition phenomena. Consequently, there arises a necessity for advanced or novel measurement techniques that can offer further insights into these phenomena. As part of a study to better understand the ignition phenomenon, this paper presents a modified Background Oriented Schlieren (BOS) method developed to study the heat transferred from sparks generated by spark plugs utilising a projected background in combination with the fast checkerboard demodulation (FCD) technique. This method provides a flexible and more suitable alternative to other BOS techniques for analysing spark ignition phenomena due to the high-resolution visualisation (spatial and temporal) even at higher pressures. Using this technique, the temperature fields generated by the spark were estimated using a simplified calibration. This work also demonstrates the use of the aforementioned method to obtain a high spatial resolution, high-speed visualisation of the heat transferred from the spark to the surrounding non-combustible medium, and the interaction of the spark with the flow field at 11 bar absolute pressure.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"66 6","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00348-025-04041-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145169669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

FIEVel: a Fast and InExpensive Velocimeter based on an optical mouse sensor FIEVel：一种基于光学鼠标传感器的快速廉价测速仪

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2025-05-26 DOI: 10.1007/s00348-025-04027-8

Robert Hunt, Eli Silver, Daniel M. Harris

{"title":"FIEVel: a Fast and InExpensive Velocimeter based on an optical mouse sensor","authors":"Robert Hunt, Eli Silver, Daniel M. Harris","doi":"10.1007/s00348-025-04027-8","DOIUrl":"10.1007/s00348-025-04027-8","url":null,"abstract":"<div><p>Fluid velocimetry is fundamental to a breadth of applications spanning academia and industry; however, velocimetry at high temporal resolution is often prohibitively costly. Here, we introduce a Fast and InExpensive Velocimeter (FIEVel) based on an optical mouse sensor. At its core, the optical mouse sensor consists of a small pixel array that acquires image data at high rates, with onboard hardware to compute and output motion in two orthogonal axes directly. We adapt this widely available integrated circuit to image illuminated particles in the bulk of a fluid as in standard particle image velocimetry (PIV). We demonstrate that FIEVel is capable of resolving two components of pointwise velocity (0d2c) nonintrusively in the bulk of a flowing fluid at rates up to 6.4 kHz, at orders of magnitude lower cost than traditional velocimetry devices. We demonstrate and validate the velocimeter across a range of flows, operating conditions, and illumination strategies. As a sample application, we measure the temporal spectrum of a grid-generated turbulent flow and show excellent agreement with traditional particle image velocimetry using a high-speed camera.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"66 6","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00348-025-04027-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144140175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Application of BOS velocimetry to full-scale helicopter flight tests BOS测速在直升机全尺寸飞行试验中的应用

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2025-05-25 DOI: 10.1007/s00348-025-04043-8

Johannes N. Braukmann, C. Christian Wolf, Anthony D. Gardner

{"title":"Application of BOS velocimetry to full-scale helicopter flight tests","authors":"Johannes N. Braukmann, C. Christian Wolf, Anthony D. Gardner","doi":"10.1007/s00348-025-04043-8","DOIUrl":"10.1007/s00348-025-04043-8","url":null,"abstract":"<div><p>Time-resolved background-oriented schlieren (BOS) data are used to calculate the two-dimensional velocity field in the wake of free-flying full-scale helicopters in ground effect. The calculation is performed based on the density gradient pattern of the helicopter engine exhaust gas passing the BOS field of view. A classical BOS evaluation allows the visualization of density gradients such as vortices and the exhaust plume. The result is the BOS displacement field. Applying the two-dimensional divergence to these data results in a pattern that is constant in shape across multiple BOS images, but convects downstream with the outwash velocity of the helicopter. Quantitative two-dimensional velocity fields are calculated using the divergence of the BOS shift as input to a second, time-resolved evaluation. Choosing an appropriate strategy for preparing and evaluating the data is critical to a reliable velocity estimation. Another important aspect is to distinguish between reliable velocity data and erroneous results in areas of reduced signal intensity due to a lack of thermal structures. The velocity data obtained are compared with an analytical outwash model and constant temperature anemometry data acquired simultaneously with the BOS images. The data show good quantitative agreement in areas of sufficient thermal structures within the field of view. This demonstrates the feasibility of BOS velocimetry to investigate large flow fields in full-scale helicopter flight tests.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"66 6","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00348-025-04043-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144131495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Experimental characterization of a rotor to dynamic collective pitch inputs in hover 旋翼在悬停时对动态集体俯仰输入的实验表征

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2025-05-24 DOI: 10.1007/s00348-025-04037-6

Patrick Mortimer, Jayant Sirohi

{"title":"Experimental characterization of a rotor to dynamic collective pitch inputs in hover","authors":"Patrick Mortimer, Jayant Sirohi","doi":"10.1007/s00348-025-04037-6","DOIUrl":"10.1007/s00348-025-04037-6","url":null,"abstract":"<div><p>Experiments were performed on a two-meter-diameter, four-bladed rotor to extract the coefficients of a dynamic inflow model. The frequency response of rotor-induced velocity to rotor thrust was found by introducing stepped-sine collective pitch inputs at frequencies of 0.2 per revolution to 0.7 per revolution, where the rotor rotational frequency was 14 Hz. The induced velocity field was measured using phase-resolved, two-dimensional, three-component particle image velocimetry (PIV) over a large region of interest (0.84 m<span>(times)</span>0.77 m) in a radial slice of the rotor flow field. The rotor thrust was measured using a hub-mounted load cell. Limited by the frame rate of the cameras, PIV was performed using an under-sampling technique in which one image pair was captured during each rotor revolution, and the time history was recreated from the phase-resolved measurements. The thrust amplitude was found to increase with input frequency, reaching 27.4% of the steady thrust at the highest input frequency. The induced velocity amplitude followed the opposite trend, decreasing to 2.0% of the steady value at the highest input frequency. Dynamic inflow states were extracted and fit to a first-order transfer function. The gain and corner frequency of the transfer function were found to be <span>(K = 34.7pm 1.52)</span> dB and <span>(b = 4.08pm 0.19)</span> rad/s, respectively, which followed a similar trend to computational studies reported in the literature.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"66 6","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144125870","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}

引用次数: 0

Time-averaged density tomography of non-axisymmetric jets with a rotating nozzle and telecentric, single-camera BOS 使用旋转喷嘴和远心单相机BOS的非轴对称射流的时间平均密度层析成像

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2025-05-24 DOI: 10.1007/s00348-025-04052-7

Fernando Zigunov

{"title":"Time-averaged density tomography of non-axisymmetric jets with a rotating nozzle and telecentric, single-camera BOS","authors":"Fernando Zigunov","doi":"10.1007/s00348-025-04052-7","DOIUrl":"10.1007/s00348-025-04052-7","url":null,"abstract":"<div><p>In this article, a method for density tomography using a telecentric BOS setup coupled with a motorized, rotating nozzle will be described. The telecentric optics allow for the disentanglement of the ray path integral and density gradient operators through Leibniz’s integral rule because the rays seen by a telecentric setup are parallel in the Schlieren domain. This enables the usage of a fast gradient inversion solver based on the rotating parallel ray integral method, previously developed by the author, to solve for the ray-integrated density fields in two dimensions for each view individually, producing a set of ray-integrated density measurements similar to a set of images captured by a regular absorption or emission-based computed tomography setup. By leveraging well-known computed tomography algorithms, such as the inverse Radon transform, a tomographic reconstruction of the average density field is quickly found only requiring a simple 2D camera calibration. A demonstration experiment setup is used to test the technique, where a low-speed hot jet produced by different nozzle shapes is measured. The 3D density fields are then converted to temperature fields and the temperatures are compared to a reference measurement with a thermocouple scanner. The strong agreement between the two measurements creates confidence that this technique can be deployed to produce quantitative measurements of the density fields in complex flows, which can be combined with 3D PIV measurements to obtain the four time-averaged thermodynamic fields in compressible jet flows.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"66 6","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00348-025-04052-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144125869","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

In vitro modeling of fluid dynamics in the left and right coronary arteries during rest and exercise conditions 休息和运动条件下左、右冠状动脉流体动力学的体外建模

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2025-05-23 DOI: 10.1007/s00348-025-04036-7

Seyyed Mahmoud Mousavi, Gianluca Zitti, Maurizio Brocchini

{"title":"In vitro modeling of fluid dynamics in the left and right coronary arteries during rest and exercise conditions","authors":"Seyyed Mahmoud Mousavi, Gianluca Zitti, Maurizio Brocchini","doi":"10.1007/s00348-025-04036-7","DOIUrl":"10.1007/s00348-025-04036-7","url":null,"abstract":"<div><p>Accurate understanding and simulation of coronary artery perfusion are crucial for assessing the heart function under varying cardiac workloads. This is particularly important given that sudden cardiac death (SCD) events have been observed during intense physical activity, not only in individuals with congenital coronary anomalies but also in healthy individuals. In response, we developed a novel in vitro laboratory setup to study the fluid dynamics of the left (LCA) and right (RCA) coronary arteries, using an anatomically accurate model of a healthy human aortic root and ascending aorta under different workloads. A key achievement is the simultaneous measurement of pressure in the left ventricle (LV), aorta (Ao), LCA, and RCA, along with flow rates in both coronary arteries. This is the first study to provide high-resolution, simultaneous in vitro data on pressure and flow values in coronary arteries under both rest and exercise conditions. During rest, the aortic pressure waveform decreases linearly, while during exercise, it displays a secondary diastolic peak. This distinctive aortic pressure feature during exercise is reflected in the coronary fluid dynamics, highlighting differences in the mechanisms of rest and exercise conditions. The RCA pressure closely mirrors the aortic pressure under all conditions, but the LCA pressure shows a secondary diastolic peak during exercise, phase-shifted by <span>(sim 0.2T)</span> from the cardiac cycle. This peak arises from a backward propagating pressure wave from its distal part, generated by myocardium contraction loads. Our findings highlight the amplified interaction of incident and reflected waves during exercise, making LCA perfusion highly sensitive to wave dynamics.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"66 6","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00348-025-04036-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144125497","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Kinematic decomposition of volumetric particle tracking velocimetry data 体积粒子跟踪测速数据的运动学分解

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2025-05-22 DOI: 10.1007/s00348-025-04035-8

Michael R. Fenelon, Yang Zhang, Peter J. Schmid, Louis N. Cattafesta III

引用次数: 0

A hybrid PIV/PSV approach for a large dynamic velocity range 大动态速度范围的PIV/PSV混合方法

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2025-05-21 DOI: 10.1007/s00348-025-04040-x

Dapeng Zhang, Wu Zhou, Cameron Tropea, Haoqin Huang, Xiangrui Dong, Tianyi Cai, Xiaoshu Cai

{"title":"A hybrid PIV/PSV approach for a large dynamic velocity range","authors":"Dapeng Zhang, Wu Zhou, Cameron Tropea, Haoqin Huang, Xiangrui Dong, Tianyi Cai, Xiaoshu Cai","doi":"10.1007/s00348-025-04040-x","DOIUrl":"10.1007/s00348-025-04040-x","url":null,"abstract":"<div><p>Particle image velocimetry (PIV), particle tracking velocimetry (PTV) and particle streak velocimetry (PSV) are well-established image-based measurement techniques for flow velocity fields; the main difference among the techniques lies in the timing sequence, i.e., the choice of illumination/exposure times and the time between image frames. These are chosen with respect to the expected range of seeding particle movement in time and the desired temporal resolution of flow fluctuations. Difficulties arise when very large differences in velocity occur within a single planar field of view, such that any single timing sequence is inappropriate for certain regions of the observed field. If for instance, the illumination time is adjusted to suit a PIV measurement at low velocities, high velocities in other flow regions will result in streaks. One question to be addressed is therefore, to what extent PIV processing algorithms can properly cope with streaks, which are possibly truncated in either of the consecutive images? In this context, the notion of ‘truncation bias’ will be introduced and evaluated. The present study investigates the possibility of combining image processing algorithms of PIV and PSV in a hybrid manner, while using a single timing sequence for image recording. After image recording, the images are segmented into regions according to which processing algorithm is most appropriate—PIV or PSV—and the respective algorithm is applied to each of the segments. This is followed by a recombination of the computed velocity field from each segment to obtain a result for the total field of view. The performance of this hybrid approach will be evaluated by generating and processing synthetic input data from a direct numerical simulation of a transitional boundary layer. An example laboratory flow is then used to demonstrate the hybrid technique in practice.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"66 6","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144108509","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}

引用次数: 0

Full-domain POD modes from PIV asynchronous patches 来自PIV异步补丁的全域POD模式

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2025-05-13 DOI: 10.1007/s00348-025-04029-6

Iacopo Tirelli, Adrian Grille Guerra, Andrea Ianiro, Andrea Sciacchitano, Fulvio Scarano, Stefano Discetti

{"title":"Full-domain POD modes from PIV asynchronous patches","authors":"Iacopo Tirelli, Adrian Grille Guerra, Andrea Ianiro, Andrea Sciacchitano, Fulvio Scarano, Stefano Discetti","doi":"10.1007/s00348-025-04029-6","DOIUrl":"10.1007/s00348-025-04029-6","url":null,"abstract":"<div><p>A method is proposed to obtain full-domain spatial modes based on proper orthogonal decomposition (POD) of particle image velocimetry (PIV) measurements taken at different (overlapping) spatial locations. This situation occurs when large domains are covered by multiple non-simultaneous measurements and yet the large-scale flow field organization is to be captured. The proposed methodology leverages the definition of POD spatial modes as eigenvectors of the spatial correlation matrix, where local measurements, even when not obtained simultaneously, provide each a portion of the latter, which is then analyzed to synthesize the full-domain spatial modes. The measurement domain coverage is found to require regions overlapping by <b>50–75%</b> to yield a smooth distribution of the modes. The procedure identifies structures twice as large as each measurement patch. The technique, referred to as <i>Patch POD</i>, is applied to planar PIV data of a submerged jet flow where the effect of patching is simulated by splitting the original PIV data. Patch POD is then extended to <b><i>3D</i></b> robotic measurement around a wall-mounted cube. The results show that the patching technique enables global modal analysis over a domain covered with a multitude of non-simultaneous measurements.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"66 6","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00348-025-04029-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143938172","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0