Experiments in Fluids最新文献_第8页

Free-motion wind tunnel testing using a three-degree-of-freedom magnetic suspension system 使用三自由度磁悬浮系统进行自由运动风洞试验

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-07-05 DOI: 10.1007/s00348-024-03839-4

Kazuyuki Ueno, Takushi Sato, Yuki Takeda, Reo Nagasaka, Mamoru Kikuchi

引用次数: 0

Detonation cell size estimation via chemiluminescence imaging in an optically accessible linear detonation tube 通过光学可及线性起爆管中的化学发光成像估算起爆单元尺寸

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-07-05 DOI: 10.1007/s00348-024-03844-7

Brandon M. Ng, Eugene N. A. Hoffman, Daniel I. Pineda, Christopher S. Combs

{"title":"Detonation cell size estimation via chemiluminescence imaging in an optically accessible linear detonation tube","authors":"Brandon M. Ng, Eugene N. A. Hoffman, Daniel I. Pineda, Christopher S. Combs","doi":"10.1007/s00348-024-03844-7","DOIUrl":"10.1007/s00348-024-03844-7","url":null,"abstract":"<div><p>An optically based experimental approach for estimating detonation cell size of premixed gas phase fuel–oxidizer mixtures in an optically accessible linear detonation tube is presented. Detonation wave fronts propagating through undiluted near-stoichiometric ethylene–oxygen mixtures in the circular detonation tube were visualized and recorded using CH* chemiluminescence imaging near 430 nm at 100 kHz for initial mixture pressures up to 22 kPa. The chemiluminescence imaging, coupled with high-speed videography, is shown to capture cellular detonation structures as small as 1.6 mm in width. The measured cell sizes increase as the initial fill pressure decreases, corroborating well-established relationships between detonation cell sizes and initial reactant pressures. The optically based method is validated against conventional soot foil measurements performed simultaneously with multiple detonations at various initial fill conditions. Both chemiluminescence images and soot foil measurements are compared to previously published cell size trends for undiluted fuel–oxygen detonations, demonstrating reasonable agreement with the established methods. Paired with the optically accessible detonation channel, the high-speed chemiluminescence imaging technique offers a passive estimation of detonation cell size for the range of conditions investigated with a faster experimental turnaround time relative to conventional methods.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"65 7","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141549035","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

Dynamics of a 3-D inlet/isolator measured with fast pressure-sensitive paint 用快速压敏涂料测量三维进气口/隔离器的动力学特性

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-07-04 DOI: 10.1007/s00348-024-03836-7

Andrew N. Bustard, Mark E. Noftz, Mitsugu Hasegawa, Hirotaka Sakaue, Joseph S. Jewell, Nicholas J. Bisek, Thomas J. Juliano

{"title":"Dynamics of a 3-D inlet/isolator measured with fast pressure-sensitive paint","authors":"Andrew N. Bustard, Mark E. Noftz, Mitsugu Hasegawa, Hirotaka Sakaue, Joseph S. Jewell, Nicholas J. Bisek, Thomas J. Juliano","doi":"10.1007/s00348-024-03836-7","DOIUrl":"10.1007/s00348-024-03836-7","url":null,"abstract":"<div><p>Fast pressure-sensitive paint (PSP) was applied to an inlet/isolator designed using the Osculating Internal Waverider Inlet with Parallel Streamlines (OIWPS) method. The dorsal isolator surface pressure was measured using anodized-aluminum PSP through transparent cast acrylic that makes up the ventral portion of the isolator. Temperature-sensitive paint was utilized to correct for the PSP’s temperature sensitivity. The model was tested under Mach 5.7 flow at Re <span>(=)</span> 8.5 <span>(times 10^6)</span> /m and 10.2 <span>(times 10^6)</span> /m in the AFOSR–Notre Dame Large Mach-6 Quiet Tunnel (ANDLM6QT) under conventional noise conditions. Flow phenomena, such as shocks originating in the inlet and flow separation at the throat, were visualized with high spatial resolution. The dynamics measured by the PSP and pressure transducers matched well where the spectral signal-to-noise ratio was above unity. Power spectral densities showed significant frequency content at <span>(approx)</span>1 kHz in the shock-wave/boundary-layer interaction (SWBLI) regions. Coherence analysis showed a linear relationship between the unsteady pressures at locations underneath different SWBLI in the isolator, with the exception of the Busemann throat shock. Temporal correlation of shock positions indicated that disturbances propagated downstream at 114% of the core-flow velocity; however, improved calculations of the core-flow velocity are needed to refine this assessment. The surface pressure fields at Re = 8.5 <span>(times 10^6)</span> /m and 10.2 <span>(times 10^6)</span> /m were quantitatively very similar, and the results in the ANDLM6QT were qualitatively similar to previous studies in the Boeing/AFOSR Mach-6 Quiet Tunnel under noisy flow.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"65 7","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00348-024-03836-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141549034","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

A second-order polynomial kernel outperforms Gaussian kernels when smoothing Lagrangian particle trajectories 在平滑拉格朗日粒子轨迹时，二阶多项式核优于高斯核

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-07-03 DOI: 10.1007/s00348-024-03848-3

Tim Berk

{"title":"A second-order polynomial kernel outperforms Gaussian kernels when smoothing Lagrangian particle trajectories","authors":"Tim Berk","doi":"10.1007/s00348-024-03848-3","DOIUrl":"10.1007/s00348-024-03848-3","url":null,"abstract":"<div><p>Accurate reconstruction of particle acceleration requires post-processing of Lagrangian particle trajectories to limit noise amplification by differentiation. Over the past two decades, many studies have used a convolution filter based on a truncated Gaussian kernel. The present work evaluates the performance of Gaussian kernels truncated at varying standard deviations. It is shown that, compared to the truncation typically used in Lagrangian particle tracking, a stronger truncation has a similar frequency response, but is superior in terms of overall noise reduction. For kernels of equal width, particle accelerations calculated using a kernel with stronger truncation have up to 20% lower noise. Alternatively, for a specified reduction in noise a shorter kernel can often be used compared to a Gaussian kernel at the commonly used truncation, resulting in less loss of data at trajectory endpoints. It is shown that at the optimal truncation, a Gaussian kernel is mathematically approximated by a second-order polynomial. In this limit, the use of a polynomial kernel has equal results at reduced computational expense compared to the Gaussian kernel.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"65 7","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141525208","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

Insights into bubble–droplet interactions in high-viscoelastic evaporating polymer droplets 高粘弹蒸发聚合物液滴中气泡与液滴相互作用的启示

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-07-03 DOI: 10.1007/s00348-024-03842-9

Gannena K. S. Raghuram, Durbar Roy, D. Chaitanya Kumar Rao, Aloke Kumar, Saptarshi Basu

{"title":"Insights into bubble–droplet interactions in high-viscoelastic evaporating polymer droplets","authors":"Gannena K. S. Raghuram, Durbar Roy, D. Chaitanya Kumar Rao, Aloke Kumar, Saptarshi Basu","doi":"10.1007/s00348-024-03842-9","DOIUrl":"10.1007/s00348-024-03842-9","url":null,"abstract":"<div><p>Polymer droplets subjected to a heated environment have significance in several fields ranging from spray drying, powder formation, and surface coating. In the current work, we study the evaporation of an acoustically levitated high-viscoelastic aqueous polymeric droplet under radiative heating. Depending on the irradiation intensity, we observe bubble nucleation in dilute regime of polymer concentration, contrary to previously observed nucleation in semi-dilute entangled regime for low-viscoelastic polymer droplets. After bubble nucleation, a quasi-steady bubble growth occurs depending on the irradiation intensity and polymer concentrations. Our scaling analysis reveals that initial bubble growth follows Plesset–Zwick criteria, independent of the viscoelastic properties of the polymer solution. Further, we establish that the onset of bubble growth has an inverse nonlinear dependence on the irradiation intensity. The droplet oscillations are primarily driven by the presence of multiple bubbles and, to some extent, by the rotational motion of the droplet. At high polymer concentrations and irradiation intensities, we report the expansion and collapse of polymer membrane without rupture, indicating the formation of an interfacial skin of significant strength. Finally, depending on the nature of bubble growth, different types of precipitate form contrary to the different modes of atomization observed in low-viscoelastic polymer droplets.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"65 7","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141552715","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-resolved phase-lock pressure-sensitive paint measurement of trailing edge noise dynamics 时间分辨锁相压敏涂料测量后缘噪声动态

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-07-02 DOI: 10.1007/s00348-024-03838-5

Masato Imai, Kohei Konishi, Keita Ogura, Kazuyuki Nakakita, Masaharu Kameda

{"title":"Time-resolved phase-lock pressure-sensitive paint measurement of trailing edge noise dynamics","authors":"Masato Imai, Kohei Konishi, Keita Ogura, Kazuyuki Nakakita, Masaharu Kameda","doi":"10.1007/s00348-024-03838-5","DOIUrl":"10.1007/s00348-024-03838-5","url":null,"abstract":"<p>Pressure-sensitive paint (PSP) was applied to the surface of a NACA0012 airfoil to investigate pressure fluctuations associated with trailing edge (TE) noise under low-velocity flow conditions. The primary focus is to assess the feasibility of employing laser pulses exposed at the airfoil surface to mitigate TE noise. However, the weak pressure fluctuations accompanying TE noise pose a challenge, as they are overshadowed by image sensor noise in high-speed cameras capturing PSP emission changes. To address this issue, a novel time-resolved phase-locking technique was introduced, utilizing the signal from a semiconductor pressure transducer at the trailing edge as a phase-lock trigger source. By repetitively conducting phase-locked measurements (1150 times), time series ensemble averaged data based on PSP emission images were obtained, enabling the capture of these subtle pressure fluctuations. Quantitatively, fluctuations with a dominant frequency of 679 Hz and an amplitude of 50 Pa are resolved within an accuracy of about 15 Pa, achieved at a recording rate of 19.2 kHz. Both the suppression and subsequent redevelopment of the pressure field with the TE noise offer valuable insights into the dynamics of TE noise and open avenues for targeted noise reduction strategies in aerodynamic applications.</p>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"65 7","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141506633","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

Influence of roughness-generated streaks on laminar separation bubbles 粗糙度产生的条纹对层流分离气泡的影响

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-07-02 DOI: 10.1007/s00348-024-03837-6

Tomek Jaroslawski, Maxime Forte, Olivier Vermeersch, Jean-Marc Moschetta, Erwin Gowree

{"title":"Influence of roughness-generated streaks on laminar separation bubbles","authors":"Tomek Jaroslawski, Maxime Forte, Olivier Vermeersch, Jean-Marc Moschetta, Erwin Gowree","doi":"10.1007/s00348-024-03837-6","DOIUrl":"10.1007/s00348-024-03837-6","url":null,"abstract":"<div><p>This experimental investigation studies the impact of streaks on two-dimensional laminar separation bubbles forming over an aerofoil. Streaks are introduced into the boundary layer using cylindrical roughness elements, and the resulting mean and unsteady flow fields are measured using hotwire anemometry. The observed streaks generated by roughness exhibit analogous behaviour to those generated by freestream turbulence, significantly altering the mean flow characteristics of the bubble, including reductions in its length, height, and the introduction of spanwise velocity gradients. These mean flow modifications have a damping effect on convective disturbance growth. The experiments suggest the coexistence of modal instability due to the laminar separation bubble and transient growth due to streaks. To investigate the combined effect of roughness and the presence of freestream turbulence, we increase the turbulence level from the baseline in the presence of a roughness forcing configuration. We find that increasing the turbulence intensity leads to an enhancement of transient growth, accompanied by distinctive chordwise disturbance growth compared to lower freestream turbulence intensity levels.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"65 7","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141525209","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

Simultaneous velocity and concentration measurements over a rippled boundary subjected to oscillating fluid forcing 在受振荡流体强迫作用的波纹边界上同时测量速度和浓度

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-06-26 DOI: 10.1007/s00348-024-03840-x

Juan C. Vargas-Martinez, Sylvia Rodríguez-Abudo

引用次数: 0

High-speed two-color scanning volumetric laser-induced fluorescence 高速双色扫描体积激光诱导荧光技术

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-06-21 DOI: 10.1007/s00348-024-03831-y

Diego Tapia Silva, Cole J. Cooper, Tracy L. Mandel, Shilpa Khatri, Dustin Kleckner

{"title":"High-speed two-color scanning volumetric laser-induced fluorescence","authors":"Diego Tapia Silva, Cole J. Cooper, Tracy L. Mandel, Shilpa Khatri, Dustin Kleckner","doi":"10.1007/s00348-024-03831-y","DOIUrl":"10.1007/s00348-024-03831-y","url":null,"abstract":"<div><p>Many problems in fluid mechanics require single-shot 3D measurements of fluid flows, but are limited by available techniques. Here, we design and build a novel flexible high-speed two-color scanning volumetric laser-induced fluorescence (H2C-SVLIF) technique. The technique is readily adaptable to a range of temporal and spatial resolutions, rendering it easily applicable to a wide spectrum of experiments. The core equipment consists of a single monochrome high-speed camera and a pair of ND: YAG lasers pulsing at different wavelengths. The use of a single camera for direct 3D imaging eliminates the need for complex volume reconstruction algorithms and easily allows for the correction of distortion defects. Motivated by the large data loads that result from high-speed imaging techniques, we develop a custom, open-source, software package, which allows for real time playback with correction of perspective defects while simultaneously overlaying arbitrary 3D data. The technique is capable of simultaneous measurement of 3D velocity fields and a secondary tracer in the flow. To showcase the flexibility and adaptability of our technique, we present a set of experiments: (1) the flow past a sphere, and (2) vortices embedded in laminar pipe flow. In the first experiment, two channel measurements are taken at a resolution of 512 × 512 × 512 with volume rates of 65.1 Hz. In the second experiment, a single-color SVLIF system is integrated on a moving stage, providing imaging at 1280 × 304 × 256 with volume rates of 34.8 Hz. Although this second experiment is only single channel, it uses identical software and much of the same hardware to demonstrate the extraction of multiple information channels from single channel volumetric images.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"65 7","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00348-024-03831-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141506634","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

The interaction between turbulent separation bubble breathing and wall pressure on a 2D wing 二维机翼上湍流分离气泡呼吸与壁压之间的相互作用

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-06-14 DOI: 10.1007/s00348-024-03835-8

Sen Wang, Bradley Gibeau, Sina Ghaemi

{"title":"The interaction between turbulent separation bubble breathing and wall pressure on a 2D wing","authors":"Sen Wang, Bradley Gibeau, Sina Ghaemi","doi":"10.1007/s00348-024-03835-8","DOIUrl":"10.1007/s00348-024-03835-8","url":null,"abstract":"<div><p>This investigation characterized the relation between the breathing motion and wall-pressure fluctuations for a turbulent separation upstream of the trailing edge of a two-dimensional wing with NACA 4418 profile. The experiments were conducted at a freestream velocity <i>U</i><sub>∞</sub> = 10.2 m/s with a turbulent intensity of 0.4%. The wing had an aspect ratio of 1.2 and an angle of attack of 9.7°. The corresponding chord-based Reynolds number was 620,000. The measurements consisted of simultaneously acquired wall-pressure measurements at various streamwise locations and time-resolved particle image velocimetry (PIV) in a streamwise-wall-normal plane. Both measurements showed unsteadiness related to the breathing motion at low Strouhal number <i>St</i><sub><i>l</i></sub> ≈ 0.05. Here, <i>St</i><sub><i>l</i></sub> is defined based on the characteristic length, <i>l</i>, of the mean turbulent separation bubble (TSB). Cross-correlation between the measured wall pressures at different streamwise locations revealed that the breathing motion propagated at approximately 0.8<i>U</i><sub>∞</sub> downstream of the mean detachment (MD) point. The breathing motion was observed to establish a stronger correlation with the low-frequency wall-pressure fluctuations in the low-intermittency regions as opposed to the high-intermittency regions. Spectral proper orthogonal decomposition was performed using the combined PIV velocity fields and wall-pressure measurements. The results revealed that the expansion (or contraction) of TSB preceded a reduction (or increase) in wall pressure measured upstream of MD and an increase (or reduction) in wall pressure measured downstream of MD. The findings align with the fact that TSB expansion occurs when local adverse pressure gradient (APG) increases, whereas contraction corresponds to a decrease in APG.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"65 7","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141341504","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