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Aligning free surface properties in time-varying hydraulic jumps Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2021-03-02 Rui Li; Kristen D. Splinter; Stefan Felder
Hydraulic jumps occur commonly in natural channels and energy dissipation systems of hydraulic structures in the violent transition from supercritical to subcritical flows. They are characterised by large flow aeration, high turbulence and strong fluctuations of the free surface and the jump toe. For free surface measurements, fast-sampling, fixed-point instruments such as acoustic displacement meters
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Accuracy improvement for directional polarized spectral emissivity measurement in the wavelength range of 4-20 μm Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2021-02-27 Longfei Li; Kun Yu; Kaihua Zhang; Yanlei Liu; Feng Zhang; Yufang Liu
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Identification based thermal reflection compensation for radiation based temperature measurements in combustion chambers Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2021-02-20 J. Matthes; M. Vogelbacher; P. Waibel; L. Gröll
When monitoring wall temperatures in reactors and combustion chambers using infrared cameras, significant measurement errors occur due to the reflection of hot objects such as flames. The radiation received in the camera from the measured wall segment results from the sum of inherent wall radiation and reflected radiation. The reflection depends on the geometrical arrangement of wall, flame and camera
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Electrowetting induced microdroplet oscillation over interdigitated electrodes for hotspot cooling applications Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2021-02-25 Israr Ahmad; Manabendra Pathak; Mohd. Kaleem Khan
Recent advancement in electrowetting technique has attracted the attention of researchers due to its numerous applications in lab-on-chip microfluidic devices. In the present work, an interdigitated electrode (IDE) configuration is introduced for producing oscillating droplets for heat dissipation in electronic devices. It resolves the problem of interfering wire used as an electrode in conventional
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An accurate calorimeter-based method for the thermal characterization of heat pipes Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2021-02-25 Joseph P. Mooney; Jeff Punch; Nick Jeffers; Vanessa Egan
This study presents a method that can be used to accurately determine the thermal performance of a cylindrical heat pipe. In the method, the heat pipe is placed between two stainless steel 304 cylindrical blocks, configured as radial calorimeters that achieve thermal contact with the evaporator and condenser sections of the pipe. A flexible isothermal electrical heater mat surrounds the evaporator
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Flow visualization in a hybrid thermoacoustic system Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2021-02-16 Lu Shen; Govind Harikumar; Kai Wang; Fei Duan
An experimental investigation is conducted to understand the flow behavior near a stack in a hybrid thermoacoustic system including resonator and looped-tube. Time-resolved particle image velocimetry measurement is applied to obtain the evolution of the local oscillating flow. Phase-averaged results show two types of vortices in the flow field due to the stack: the primary vortices attaching at the
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Two-phase pressure drop and void fraction in a cross–corrugated plate heat exchanger channel: Impact of flow direction and gas-liquid distribution Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2021-02-24 Susanne Buscher
Two-phase pressure drop is studied in a transparent cross-corrugated channel for uniform and non-uniform gas-liquid distribution. Both uniform and non-uniform two-phase distributions are created by injecting air and water through different numbers of nozzles directly into the channel. The frictional pressure drop clearly indicates the impact of maldistribution. The experimental data is analyzed by
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Parametric effects on the flow redistribution in ballooned bundles evaluated by magnetic resonance velocimetry Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2021-02-24 A.V.S. Oliveira; D. Stemmelen; S. Leclerc; T. Glantz; A. Labergue; G. Repetto; M. Gradeck
When the water inventory evaporates during a hypothetical loss of coolant accident in the core of a pressurized water reactor, the fuel rods temperature increases substantially, resulting in the clad ballooning and the formation of blocked sub-channels. During the reflooding phase, where water is injected into the core and a steam-droplets flow is created above the water level, the presence of ballooned
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Effect of reynolds number on turbulent boundary layer approaching separation Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2021-02-21 Artur Dróżdż; Paweł Niegodajew; Mathias Romańczyk; Witold Elsner
The effect of Reynolds number on turbulent boundary layer under adverse pressure gradient has been barely investigated in the available literature. So far, experimental or numerical research on that issue were performed either for low Re or for low range of Re to capture its clear effect on flow statistics. Hence, the purpose of the present paper is to examine whether the effect of Reynolds number
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Interfacial dynamics of air–liquid flow in eccentric drainpipe while draining from a square tank Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2021-02-10 Ranjana Rathaur; Sumana Ghosh
The present study investigates the influence of liquid properties and port position on draining characteristics from a square tank. Four different liquids, water, kerosene, glycerol 20%, and glycerol 60% are used. Three different port positions of a drainpipe of 9 mm id are used. Bubbly, slug, churn, elongated slug, and annular flow are observed in the drain port. Slug and bubbles never collide and
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Investigation of the impact characteristics and pulse mechanism of a self-excited aspiration pulsed jet device Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2021-02-14 Xinyang Liu; Hongzeng Xu; Li Zhao; Xiaolong Yu; Hao Chen; Shibin Zhang; Jianhong Ji
In this paper, based on the traditional low-frequency self-excited oscillation pulsed jet device, a self-excited aspiration pulsed jet device is designed. For the structural parameters, including the aspiration capacity, impact characteristics, and pulse generation mechanism, the jet impingement is analyzed experimentally under the aspiration and non-aspiration conditions. It was found that, compared
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Evaporation Characteristics and Heat Transfer Enhancement of Sessile Droplets under Non-uniform Electric Field Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2021-02-19 Haojie Xu; Junfeng Wang; Jiameng Tian; Yuanping Huo; Bin Li; Dongbao Wang; Wei Zhang; Jiang Yao
Electrohydrodynamic (EHD) enhancement of water droplet evaporation by non-uniform electric field and the subsequent dynamic characteristics were experimentally investigated in this paper. A pin-to-plate electric field was produced by a needle connected to a high-voltage power supply and the grounded heated surface coated by thin Teflon film with a contact angle of about 100°. The droplet was generated
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Bubble characteristics affecting air-water exchange in open-channel flow with a jet forming over a sudden bottom drop Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2021-02-05 Hang Wang; Xuechun Liu; Ruidi Bai; Shanjun Liu
Entrainment of air bubbles into flowing water increases significantly the interfacial area between the two phases hence enhancing the air-water mass transfer. The air bubble characteristics are thus of direct relevance to the waterbody aeration and oxygenation, which should be understood in the context of bubbly-flow turbulence development. In this paper, we studied experimentally a canonical aerated
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Study of initial stage of entry of a solid sphere into shallow liquid with Synthetic Schlieren technique Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2021-02-18 Andrey V. Cherdantsev; Nikolay V. Gavrilov; Evgeny V. Ermanyuk
Vertical entry of a 213 mm diameter solid sphere moving with a low speed of 16 – 40 mm/s onto a shallow liquid layer is investigated experimentally. The focus of the study is on deformation of the free surface before the actual contact between solid and liquid in presence of air cushioning. Owing to local character of air cushioning, the sphere is modeled by a spherical segment. The measurements were
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Effect of wettability on droplet impact: Spreading and splashing Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2021-02-08 Haixiang Zhang; Xiwen Zhang; Xian Yi; Feng He; Fenglei Niu; Pengfei Hao
This study experimentally investigates the dynamic behaviors of water droplets over wide ranges of diameters and velocities (200 μm < D0 < 2600 μm, 50 < We < 3000) impacting on surfaces with various wettability (ranging from hydrophilic to superhydrophobic), and focuses on the effect of surface wettability on water droplet spreading and splashing. The experimental results show that the surface wettability
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Modes of plasma-stabilized combustion in cavity-based M = 2 configuration Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2021-02-11 Sergey B. Leonov; Skye Elliott; Campbell Carter; Alec Houpt; Philip Lax; Timothy Ombrello
This paper considers the modes of plasma-stabilized supersonic combustion in a cavity-based flameholding configuration. The testing was performed in the SBR-50 supersonic facility at the University of Notre Dame under the following conditions: Mach number M = 2, stagnation pressure and temperature P0 = 1–3.2 bar, T0 = 295–750 K, and an ethylene injection rate of ṁC2H4 = 0–8 g/s. A rail type electric
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Visualized experiments on phase-change heat transfer of a metal “endoscopic” two-phase closed thermosyphon Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2021-02-05 Huicong Yao; Guang Li; Yinfeng Wang; Yuezhao Zhu
A novel metal “endoscopic” two-phase closed thermosyphon (METPCT) which could be used to intuitively investigate the phase-change heat transfer and two-phase flow characteristics were developed. The visualized experimental set-up was established by using a rigid borescope and a high-speed camera. The phase-change heat transfer characteristics of the internal working fluid inside the METPCT under various
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On the width and mean value of bubble size distributions under subcooled flow boiling Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2021-02-06 Marcos Conde-Fontenla; Concepción Paz; Miguel Concheiro; Gherhardt Ribatski
In this work, a new comprehensive dataset about bubble sizes in flow boiling of water is presented. The experimental setup basically consists of a lower copper heated plate embedded in a horizontal rectangular channel flow. Several experimental conditions, ranging bulk velocities: 0.1–0.9 [m·s−1]; mass fluxes: 96.9–871.8 [kg·m−2·s−1]; subcooling degrees: 16–36 [°C]; heat fluxes: 200–650 [kW·m−2] and
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Experimental investigation of the characteristics of the transition from spherical cap bubble to slug flow in a vertical pipe Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2021-02-06 M. Abdulkadir; B. Ugwoke; L.A. Abdulkareem; D. Zhao; V. Hernandez-Perez
Reliable and accurate prediction of the transition from spherical cap bubble to slug flow is crucial not only to the operation of industrial facilities such as the crude oil pipelines, bubble column, and nuclear reactors but also for model development for computational fluid dynamics (CFD) studies. The present paper presents a review of the transition mechanics from spherical cap bubble flow to slug
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Local dynamics of pharmaceutical powder fluidization using high speed long distance microscopy and particle image velocimetry Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2021-02-05 K. Elserfy; S. Cheng; H-K. Chan; A. Kourmatzis
The local dynamics of fluidized pharmaceutical carrier powders in a turbulent channel flow was studied using particle image velocimetry (PIV) and High-speed, long-distance microscopy (HS-LDM). Four different lactose powders which have been used as a drug carrier in dry powder inhalers were used in this study. These powders have median powder particle diameters ranging between 61 and 121 µm. Air flow
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Surface conductivity effects during shock wave reflection off curved surfaces Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2021-02-06 A. Cohen; B.W. Skews
Previous work has shown that heat transfer into a plane conducting surface affects shock wave reflection properties. In the more complex reflection case of a curved surface the situation would be different because of the increased number of reflection patterns, with a rapid change in reflection geometry as the wave propagates up the surface. Test pieces of different thermal conductivities (0.19 W/mK
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Three-cylinder rotating system flows and their effects on a downstream dimpled airfoil Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2021-01-07 Al Habib Ullah; Braden L. Rostad; Jordi Estevadeordal
Effects from turbulence levels created by a three-cylinder rotating system on the flow over a dimpled surface of an airfoil are reported. The three-cylinder rotating system effect is tested on the flow over a NACA0015 with leading-edge dimples at various angles of attack at Reynolds numbers of 0.5 × 105 and 1.0 × 105 in a low-speed wind tunnel. To the effect of mimicking free-stream flow perturbations
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Experimental study on the lock-in of an oscillating circular cylinder confined in a plane channel Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2021-01-21 Peng Zhang; Zhiping Li; Tianyu Pan; Lin Du; Qiushi Li; Jian Zhang
The results of an experimental study concerning wall boundary effects on the lock-in behavior of the shedding vortex of a circular cylinder, which is forced to oscillate transversely in a uniform flow at moderate Reynolds number Re = 2000, are presented in this paper. A height-adjustable flow channel is designed to study the boundary effect. Two sets of experiments are organized to study the lock-in
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Compound analysis of gas bubble trajectories with help of multifractal algorithm Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2021-01-23 Jakub Augustyniak; Dariusz M. Perkowski
Three-dimensional trajectories of gas bubbles were the subject of study in this article. Authors carried out experiments in two glass tanks with dimensions of 300 × 300 × 1500 mm and 300 × 150 × 500 mm, respectively, filled with distilled water with a temperature equal to T = 21 ± 1 °C. The tests were carried out for an air volume flow rate, values from 0.00492 l/min to 0.0645 l/min. Basic characteristics
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Zero-crossing rate method as an efficient tool for combustion instability diagnosis Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-12-27 Seongpil Joo; Jongwun Choi; Namkeun Kim; Min Chul Lee
A novel methodology based on the zero-crossing rate (ZCR) is introduced to diagnose combustion instability (CI) in a combustion system. This method can assess the combustion status by counting the number of points of dynamic pressure (DP) signals crossing zero in a cycle, and quantifies the cyclic variation of the number of crossing points. To validate the feasibility of this method, transition experiments
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3D Lagrangian particle tracking of a subsonic jet using multi-pulse Shake-The-Box Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2021-01-19 Peter Manovski; Matteo Novara; Nagendra Karthik Depuru Mohan; Reinhard Geisler; Daniel Schanz; Janos Agocs; Philipp Godbersen; Andreas Schröder
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Self-similarity for statistical properties in low-order representations of a large-scale turbulent round jet based on the proper orthogonal decomposition Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2021-01-08 R. Kapulla; K.H. Manohar; S. Paranjape; D. Paladino
This study is an experimental investigation into the self-similarity behavior of first and second order statistical quantities derived from a jet flow based on a) the original data and b) its low-order representations derived from the Proper Orthogonal Decomposition (POD) and c) a comparison of both. The flow under investigation is an air-helium turbulent round jet with Re≈15400 emerging from a tube
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Experimental investigation on the effect of equivalence ratio on the development of cellular structure of E30-air mixture Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-12-24 Chenghan Sun; Yikai Li; Zechang Liu; Xu He; Fushui Liu
Ethanol is a renewable, clean fuel and is usually blended with gasoline to be used as an alternative fuel for internal combustion engines. In the present study, the instability development and cellular structure evolution of a spherically expanding flame of E30 (gasoline blended with ethanol of 30% liquid volume) are investigated. By processing the flame images, the equivalent diameters of cells on
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Experimental study and application of an artificial neural network (ANN) model on pulsed spray cooling heat transfer on a vertical surface Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2021-01-07 P. Liu; R. Kandasamy; T.N. Wong
An experimental study is conducted on pulsed spray cooling heat transfer on a vertical surface under controlled nozzle pressure. Nozzle flow rate is found to be directly proportional to the duty cycle when the nozzle pressure is maintained constant and hence fixed at 2 bar throughout the investigation. The temperature fluctuates on the heated surface due to the interaction of the injection/non-injection
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Baffled tubes with superimposed oscillatory flow: Experimental study of the fluid mixing and heat transfer at low net Reynolds numbers Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-12-23 J. Muñoz-Cámara; D. Crespí-Llorens; J.P. Solano; P. Vicente
Experimental results of flow pattern and heat transfer in circular-orifice baffled tubes under pure oscillatory flow and compound flow conditions are presented. The hydrogen bubble visualization technique is employed for describing the unsteady flow structure, and particle image velocimetry is used in order to measure the velocity field during eight different phases of the oscillation cycle. The existence
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Experimental investigation on the propagation characteristics of detonations in a semi-confined straight channel Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-12-27 Zhicheng Wang; Ke Wang; Minghao Zhao; Yiyuan Zhu; Zhongtian Jiao; Qingan Li; Wei Fan
In a rotating detonation engine, detonation waves propagate in the combustor chamber with one side unconfined which will introduce lateral relief and, therefore, results in deficits of the propagation velocity and the peak pressure. To study the critical mixture height for detonation propagation, a simple combustor without considering the curvature has been used, which provides a planar semi-confined
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Measurement of thickness and analysis on flow characteristics of upper swirling liquid film in gas-liquid cylindrical cyclone Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-12-24 Ya-An Wang; Jian-Yi Chen; Ti Yue; Yang Yang; Ming-Shan Han; Chao-Yu Yan
The gas-liquid cylindrical cyclone (GLCC) is a device used to separate gas from liquid in offshore or subsea oil and gas production systems. The liquid film swirling along the upper cylinder wall in the GLCC is referred to as “upper swirling liquid film” (USLF). The flow patterns of USLF have a great influence on GLCC’s separation performance. However, the dynamics of the gas-liquid flow in a GLCC
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Experimental and numerical investigation of turbulent wake flow around wall-mounted square cylinder of aspect ratio 2 Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2021-01-03 Fei Wang; Kit Ming Lam
The turbulent wake velocity fields around a short wall-mounted square cylinder of aspect ratio 2 fully immersing into a thick turbulent boundary layer are obtained experimentally with PIV and numerically with LES. Comparison between the two sets of data is made on the time-averaged mean velocities, turbulent fluctuating velocities, and the detailed characteristics of energetic large-scale coherent
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The effect of freestream turbulence on convection enhancement by a flexible strip Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-12-28 Yang Yang; David S.-K. Ting; Steve Ray
Turbulence generators such as a 25.4 mm tall, 12.7 mm wide (W) and 0.1 mm thick rectangular flexible strip can provide a robust means of enhancing convective heat transfer. This wind-tunnel study aimed at uncovering the effect of freestream turbulence on heat convection enhancement of a flat surface by a flexible strip. The freestream turbulence was furnished by a 6 mm thick orificed perforated plate
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Influence of multiple air bubbles on the collapse strength of a cavitation bubble Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-12-19 Jian-Bo Li; Wei-Lin Xu; Yan-Wei Zhai; Jing Luo; Han Wu; Jun Deng
Studying the effect of multiple air bubbles on the collapse strength of a cavitation bubble can aid in understanding the mechanism of air entrainment alleviating the cavitation erosion and enhance the aeration effects in hydraulic engineering. A cavitation bubble is generated by the spark-generated system. Air bubbles are arranged in three manners: two air bubbles on the same side, one air bubble on
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DMD analysis for velocity fields of a laminar premixed flame with external acoustic excitation Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-12-28 Yao Yang; Yuanqi Fang; Liang Zhong; Yifan Xia; Tai Jin; Jingxuan Li; Gaofeng Wang
The velocity fields of the laminar premixed flames with external acoustic excitation are studied in this work. The velocity fields in both burnt and unburnt regions have been experimentally investigated by PIV methodology. Different acoustic modulations have been applied to the flames. Dynamical mode decomposition (DMD) is adopted to elaborate the interaction mechanisms between flames and acoustics
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Comparative study of mass transfer distributions and oil-flow visualizations with image analysis on long and short 90° elbows Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-12-24 Nobuyuki Fujisawa; Tomohiro Takizawa; Takayuki Yamagata
To understand the mass transfer mechanism of 90° elbows, a comparative study of mass transfer measurements and oil-flow visualization with image analysis is carried out for long and short 90° elbows in the Reynolds numbers Re = 5 × 104 –2 × 105. The mass transfer distributions are evaluated by using the plaster-dissolution method, while the oil-flow fields are quantitatively visualized by oil-flow
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Experimental investigation of inclination angle effect on unsteady film coverage of double-row staggered-holes at vane leading edge using time-resolved quantitative light sheet technique Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-12-28 Wen-li Zhou; Jian Pu; Xin Huang; Jian-hua Wang; Wei Song; Wei-long Wu
Turbine vane leading edge features the highest heat load and is effectively protected by multi-row film-ejections. In present work, time-resolved planar quantitative light sheet (QLS) technique was proposed to acquire unsteady behaviors of film coverage and jet-trajectory caused by fluid-interaction. Under proper calibrations, the uncertainty of transient concentration measurement was controlled below
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On the effect of orifice thickness and divergence angle in the near and intermediate fields of axisymmetric jets Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-11-28 Tengfei Cai; Jin-Tae Kim; Shyuan Cheng; Fei Ma; Leonardo P. Chamorro
We experimentally explored the distinct effects induced by the geometry of various axisymmetric orifices in the near and intermediate regions of jets at a Reynolds number of Re≈105 based on the diameter, d=10 mm, of the orifices. The orifices inspected had thicknesses of ∊/d=0.2, 1 and 2 and divergence angles of θ=0∘,20∘ and 45∘. High-speed planar particle image velocimetry (PIV) was used to characterize
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Corrosion behavior of X65 steel at different depths of pitting defects under local flow conditions Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-12-31 Dalei Zhang; Liuyang Yang; Zhuowei Tan; Shaohua Xing; Shuyu Bai; Enze Wei; Xiao Tang; Youhai Jin
The electrochemical corrosion behavior and the development mechanism of the local corrosion of X65 steel under different defect depths were studied by using macroscopic electrochemical measurements and characterization techniques. A CO2-saturated NACE solution was used to study electrochemical corrosion characteristics in the single-phase flow-accelerated corrosion test loop system. Changes in the
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An experimental study of non-spinning stone-skipping process Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-12-19 Hsuan-Wei Tsai; Wen-Fang Wu; Chun-Liang Lai
The process of throwing a small aluminum circular disk toward the water surface to simulate the stone-skipping phenomenon is experimentally observed and analyzed in this paper. Four stages consisting of pre-hitting, hitting, sliding, and aft-sliding stages for a single skipping process are proposed for a thorough analysis and better understanding of the fundamental physical mechanism of the stone-skipping
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The flow-field within a vortex-based solar cavity receiver with an open aperture Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-12-09 Shen Long; Timothy C.W. Lau; Alfonso Chinnici; Graham J. Nathan
We report a systematic experimental study to characterise the isothermal flow-field within a vortex-based solar cavity receiver with an open aperture. Measurements were performed using particle image velocimetry for a fixed flow rate through the inlet jets to achieve Reynolds number of ReD = 11800. A range of flowrates through the outlet were assessed for a fixed inlet flow rate, including that where
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Two-dimensional liquid sheet in transverse subsonic airflow Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-12-17 A. Jaberi; M. Tadjfar
Flow dynamics of a two-dimensional liquid sheet injected transversely into a subsonic airstream was comprehensively investigated. An injector with an aspect ratio of 90 and a thickness of 0.35 mm was used to produce the two-dimensional liquid flow. Experimental visualizations were used to identify the main features of the liquid sheet in crossflow. Tests were conducted for a wide range of flow conditions
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Volumetric flow characterisation of a rectangular orifice impinging synthetic jet with single-camera light-field PIV Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-12-17 Zhou Zhao; Junfei Ding; Shengxian Shi; Rene Kaufmann; Bharathram Ganapathisubramani
The formation and evolution of volumetric flow structures from a rectangular orifice synthetic jet (AR=10, Re=550, Sr=0.0117, and Lo=0.0855m) impinging on a flat plate is investigated using phase-locked single-camera light-field particle image velocimetry (LF-PIV). An impinging plate is located 24 orifice widths away from the rectangle orifice and this volumetric flow data is used to capture the mechanisms
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Dripping–jetting transition of liquid stream from plate-type micro-orifice affected by wetting and dewetting Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-12-19 Liang Hu; Yanshen Fang; Lei She; Rui Su; Xin Fu
The liquid stream from an orifice typically undergoes a transition process from dripping to jetting under increased pressure. The dripping–jetting (D–J) transition performance from a thin-walled tube or an orifice with a wide diameter has been well studied, where the triple contact line of the stream is pinned on the edge of the orifice and the flow behaviors are analyzed accordingly with a precondition
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Screech feedback loop and mode staging process of axisymmetric underexpanded jets Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-12-13 Xiangru Li; Nianhua Liu; Pengfei Hao; Xiwen Zhang; Feng He
Acoustic measurements and time-resolved schlieren visualizations are performed on underexpanded jets issuing from a convergent nozzle to investigate the screech feedback loop and the mode staging phenomenon. In the present experiments, the nozzle pressure ratio ranges from 2.00 to 4.00. The instability mode of the jet successively experiences the axisymmetric A1 and A2 modes, the flapping B mode and
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Design and validation of a capacitance-based sensor for slurry density measurement Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-11-23 Maria Teresa Scelzo; Pinar Eneren; Yuki Sakamoto; Laura Peveroni
This work presents the design and the validation of a non-intrusive capacitance-based densimeter, for the on-line measurement of solid fraction in a slurry pipe flow. An asymmetrical type capacitance sensor was designed by means of numerical electric field analysis. The simulations conducted at different solid volume fractions revealed that the sensor is not sensitive to the distribution and the size
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Self-excited noise generation from laminar methane/air premixed flames in thin annular jets Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-12-10 Seong-Ho Jin; Jae-Hoon Joung; Suk-Ho Chung
Self-excited noise generation from laminar flames in thin annular jets of premixed methane/air has been investigated experimentally. Various flame shapes were observed in this flow configuration, including conical shaped flames, ring shaped flames, steady crown shaped flames, and oscillating crown shaped flames. Self-excited noise with a total sound pressure level of about 70 dB was generated from
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Mixed LSE and EPOD based technique for multi-plane PIV measurements synchronization in separated flow condition Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-12-08 Matteo Dellacasagrande; Jacopo Verdoya; Dario Barsi; Davide Lengani; Daniele Simoni
A combination of the Linear Stochastic Estimation (LSE) and a modified version of the Extended Proper Orthogonal Decomposition (EPOD) is proposed to link multi-plane particle image velocimetry (PIV) data describing transitional separated boundary layers. Measurements have been obtained in two orthogonal planes, which share a common line providing the spatial consistency between the data sets. A wall-normal
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Comparison of bubble parameters between boiling and hydrogen evolving systems Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-12-13 Hae-Kyun Park; Bum-Jin Chung
Bubble behavior in a hydrogen evolving system was compared to that under boiling conditions. Hydrogen was generated electrochemically in an aqueous solution of 1.5 M sulfuric acid (H2SO4). Hydrogen bubble parameters such as active nucleation site density, bubble departure diameter, and bubble frequency, were measured and compared to those observed during boiling. The hydrogen evolving system exhibited
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Fast estimation of the enthalpy–temperature function of Phase Change Materials Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-12-09 Jean-Luc Dauvergne; Ángel Serrano; Elena Palomo Del Barrio
This paper presents a method for fast estimation of the enthalpy–temperature function of Phase Change Materials (PCMs). The method combines a simple experimental setup with a non-iterative, reliable mathematical algorithm that allows retrieving the enthalpy–temperature function from measurements of heat flux and temperature at a single point. Distilled water was used as reference PCM for validation
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Experimental investigation on atomization properties of impaction-pin nozzle using imaging method analysis Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-12-11 Hongjun Sun; Yikun Luo; Hongbing Ding; Jinxia Li; Chenrui Song; Xixi Liu
The impaction-pin spray nozzle is widely used in chemical and process industries. To study the atomization characteristics of the impaction-pin nozzle, a high-pressure atomization apparatus was developed and an optical imaging system for the measurement of droplet parameters was proposed. The droplet size and velocity vector were extracted from the shadowgraph images and the influence of liquid pressure
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Dual-perspective boundary layer thickness measurements using filtered natural emissions of species Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-12-10 J.A. Piehl; O. Samimi-Abianeh
Boundary layer thickness measurements have been taken via spectroscopic methods in the past, but were traditionally limited to a single point of view due to the need of an excitation source (such as a laser) and a detector. A new optical technique that measures the broadband filtered natural emissions of species does not require an excitation source to measure the boundary layer and thus can be used
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Flow boiling heat transfer and associated bubble behaviors over backward- and forward-facing steps Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-11-30 Bo Yuan; Yonghai Zhang; Lei Liu; Jinjia Wei
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Experimental study of compact swirl flames with lean premixed CH4/H2/air mixtures at stable and near blow-off conditions Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-11-16 Weijie Zhang; Jinhua Wang; Runze Mao; Wenjun Lin; Bingxuan Lin; Yun Wu; Meng Zhang; Zuohua Huang
An experimental study on the compact lean premixed flames stabilized on a bluff-body and swirl burner is performed. The flames are featured with a strengthened Inner Recirculation Zone (IRZ). The objective is to identify the critical causes of blow-off near the lean limit. Meanwhile, the effects of hydrogen addition on the flame stabilization are also examined. Premixed CH4/H2/air mixtures are adopted
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Control of the flow in the near wake of an airfoil at full stall using fixed trailing-edge plates Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-11-21 Gokturk M. Ozkan
This work aims to control the unsteady flow structure of a NACA0012 under full stall by limiting the vortex roll-up from its trailing edge. In this regard, plates with varying lengths at zero incidences were attached at the trailing edge of the airfoil at an angle of attack of α = 16° and low Reynolds number of Rec = 2.0 × 104. Under these conditions, the flow separates near the leading edge and rolls
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Local flow structure and turbulence quantities inside a heated rectangular riser in turbulent forced and mixed convection heat transfers Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-11-21 Sin-Yeob Kim; Chan-Soo Kim; Hyoung Kyu Cho
Heat transfer deterioration in turbulent mixed convection affects the performance and safety of various pieces of industrial equipment. The reactor cavity cooling system (RCCS), a passive safety system in a very high temperature gas-cooled nuclear reactor (VHTR), incorporates rectangular riser channels to remove residual heat emitted from the reactor vessel, where turbulent mixed convection may occur
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Flame development characteristics inside a reverse-flow combustor at early stages of combustion Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-09-28 Zahra Mollahoseini; Ramin Heydarlaki; Peter Kostka; William Aitchison; Sina Kheirkhah
Characteristics of flame development and the influence of reverse-flow configuration on these characteristics few seconds after ignition are investigated experimentally. Simultaneous and high-speed OH∗ chemiluminescence and pressure measurements are performed. Methane is used as the fuel, and the fuel–air equivalence ratio is 0.7. Four experimental conditions pertaining to mean bulk flow velocities
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Effective use of the streamwise waviness in the control of turbulent separation Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-11-06 Artur Dróżdż; Paweł Niegodajew; Mathias Romańczyk; Vasyl Sokolenko; Witold Elsner
It is commonly known that for a sufficiently high Reynolds number, for flow over a rough surface and other previously examined wall topologies, turbulent boundary layer separation generally occurs earlier, and the separation bubble is noticeably larger due to a greater momentum deficit caused by wall irregularities. The recently discovered amplitude modulation effect has provided an improved understanding
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Investigation of the flow redistribution upstream of grid-like obstacles separated by a variable gap Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-11-05 Jérome Cardolaccia; Stanislas de Lambert
In nuclear Pressurized Water Reactors, fuel assemblies are slender structures composed of many rods held together by regularly spaced grids. Intense in-core conditions may sometimes result in permanent deformations impairing the reactor normal operation or even challenging its safety. Fluid-structure interactions are the central plot of this multiphysical storyline, and the water gaps between adjacent
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