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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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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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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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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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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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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 x 105 and 1.0 x 105 in a low-speed wind tunnel. To the effect of mimicking free-stream flow perturbations
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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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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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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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Dependence of boundary layer thickness on layer height for extended localised heaters Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-11-08 A. Sukhanovskii; A. Evgrafova
Dependence of boundary layer thickness on layer height in laminar and transient regimes is studied for convection from localised heat source with an open surface. The measurements of Nusselt number and characteristic frequency of thermal plume formation are done for a wide range of Rayleigh number, different Prandtl numbers and different aspect ratios. The obtained results prove that for the developed
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Experimental study of water evaporation rate, at the surface of aqueous solution, under the effect of a discontinuity of chemical potential – Effect of water activity and air pressure Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-11-01 J.-C. Bénet; S. Ouoba; F. Ouedraogo; F. Cherblanc
The aim of this communication is to analyse the influence of water activity and total pressure on water evaporation. The system is composed of liquid and gas phases, separated by a plane surface, contained in a cylinder whose volume is regulated by a piston. Water activity is regulated by saturated salt solutions and pressure by the piston. The experimental device and procedures were defined to limit
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A free convection heat transfer correlation for very thin horizontal wires in rarefied atmospheres Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-11-18 Lilian Peinado; Victor Muntean; Isabel Pérez-Grande
Mars and upper Earth atmosphere missions are booming in recent years increasing the interest in heat transfer in rarefied gases. At these low pressures, the heat transfer problems involving small geometries whose characteristic length is of the order of the mean free path of the gas molecules, raises new difficulties. This being especially severe in the case of free convection, where the velocity of
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The critical lower radius limit approach for laminar flame speed measurement from spherically expanding stretched flames Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-10-22 Berk Can Duva; Lauren Elizabeth Chance; Elisa Toulson
Spherically expanding flames are severely affected by flame stretch in the early stage of combustion and therefore stretch models are of great importance in determining the uncertainty of experimental laminar flame speeds (SL) and burned gas Markstein lengths (Lb). In order to prevent the existing large scatter in experimental data of these two fundamental flame parameters, the effect of the lower
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Ultrasound-enhanced diffusion and streaming of colloids in porous media Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-11-02 Hsiang-Lan Yeh; Jaime J. Juárez
Diffusion of colloidal particles in porous media is critical for the development of specially engineered colloids used to aid the recovery of oil from a petroleum reservoir. However, shielded structures, such as dead-end pores, prevent these colloids from reaching the available oil. This article examines the use of ultrasound fields as a mechanism for increasing the mobility of colloidal particles
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Assessing the validity of regular wave theory in a short physical wave flume using particle image velocimetry Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-10-28 Christian Windt; Alix Untrau; Josh Davidson; Edward J. Ransley; Deborah M. Greaves; John V. Ringwood
The modelling of ocean waves is an integral part of coastal and offshore engineering. Both theoretical and experimental modelling methods are available and are commonly used in support of each other. In particular, due to the difficulty in measuring the velocity throughout the water column, the wave kinematics are often derived, by means of wave theory, from a measurement of the free surface elevation
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Experimental study on the droplet characteristics in the spray tip region: Comparison between the free and impinging spray Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-11-04 Cheng Zhan; Hongliang Luo; Feixiang Chang; Keiya Nishida; Youichi Ogata; Chenglong Tang; Zehao Feng; Zuohua Huang
In this work, we compared the microscopic characteristics of the free and impinging spray tip using double-pulse laser particle image analysis technique. Droplet population density, diameters, and velocities were experimentally resolved for both the free and impinging spray at three spray tip penetration positions (STP = 32, 37 and 42 mm) under three injection pressures (10, 20 and 30 MPa). Results
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Acoustic and flow characteristics of an airfoil fitted with morphed trailing edges Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-11-08 Hasan Kamliya Jawahar; Mahdi Azarpeyvand; Carlos R. Ilário da Silva
An experimental study of a simple NACA 0012 airfoil fitted with two different flap profiles was carried out to characterize their aerodynamic and aeroacoustic performance. The airfoil with a flap deflection angle of β=10° was tested for a wide range of angles of attack at a chord-based Reynolds number of Rec=2.6×105. The aerodynamic lift and drag measurements show improved lift-to-drag performance
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Direct local heat flux measurement during water flow boiling in a rectangular minichannel using a MEMS heat flux sensor Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-10-31 Masanori Morisaki; Shota Minami; Koji Miyazaki; Tomohide Yabuki
Heat transfer characteristics of water flow boiling in a minichannel were investigated through the direct measurement of local heat flux using a fabricated MEMS heat flux sensor with a multi-layered structure. Local temperatures and heat fluxes in the water flow boiling were measured at a sampling frequency of 10 kHz in synchronism with the high-speed visualization of the boiling behavior. The measurement
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New droplet aero-breakup mechanism associated to unsteady flow loading Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-11-02 A. García-Magariño; S. Sor; A. Velazquez
Experimental testing on the unsteady aero-breakup of ethyl alcohol droplets was carried out at the rotating arm facility of INTA. The selection of the working fluid was driven by the need to explore wider ranges of the dimensionless parameters that govern the problem. A model airfoil was attached at the end of a 2.3 m long rotating arm driven by an electric motor. Droplets, whose diameter ranged from
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Investigation of evaporating sprays in a medium speed marine engine Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-11-03 Haohan Li; Roel Verschaeren; Tarek Beji; Sebastian Verhelst
The understanding of diesel sprays is very important to enable a better and cleaner marine engine design, but unfortunately little knowledge is openly available on marine engine fuel sprays. In this paper, evaporating sprays for medium speed marine engines were studied in a constant volume combustion chamber by performing optical measurements through Schlieren and Mie diagnostic techniques. The effects
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Stabilisation of condensate flow from curvilinear surfaces by means of porous media for space applications Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-10-22 Ella Barakhovskaia; Andrey Glushchuk; Patrick Queeckers; Carlo S. Iorio
A new concept of vapour condenser is proposed to solve the drainage problem and to provide an effective condensate flow under weightlessness conditions. The concept combines the capability of a curvilinear surface to drive liquid, and a combination of a porous media and a pump, as an active condensate retraction system. The porous media collects and stores the condensed fluid and acts as a barrier
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An experimental study of the aerodynamics of micro corrugated wings at low Reynolds number Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-10-28 Nasim Chitsaz; Kamran Siddiqui; Romeo Marian; Javaan Chahl
In this paper, an experimental study was performed to examine the flow characteristics of fabricated micro corrugated wings by fully mimicking the real 3D Odonata wing. For this purpose, a true scale hind wing from the Orthetrum caledonicum species with a semi span length of 60 mm was reconstructed by non-destructive close-range photogrammetry and fabricated with an advanced 3D printer. The accuracy
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Application of supercritical water conditions to improve the flowback of fracturing fluid in ultra-low-permeability sandstone formations Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-10-24 Ying Li; Xiaojiang Cui; Haitao Li; Shengnan Chen; Mingjun Chen
Hydraulic fracturing is an important approach for stimulating the production of ultra-low-permeability oil reservoirs; however, the low flowback efficiency of the fracturing fluid (FF) may cause contamination of the groundwater and reduce oil recovery. This study experimentally investigates the possibility of improving the flowback efficiency of water-based FF and oil production through the achievement
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Experiments on splashing thresholds during single-drop impact onto a quiescent liquid film Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-10-24 Tomio Okawa; Kohei Kubo; Katsuyuki Kawai; Sota Kitabayashi
The process of normal impingement of a single drop onto a quiescent liquid film was investigated experimentally to determine the thresholds of the early and late splashes. Seven liquids of different hydraulic properties were used and the liquid film thickness was varied within about 0.2–3 times the impacting drop diameter. It was found that the critical Weber number for the early splash to occur is
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Measurement of dynamics of laser-induced cavitation around nanoparticle with high-speed digital holographic microscopy Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-10-09 Linglong Wang; Yingchun Wu; Xuecheng Wu; Kefa Cen
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High-speed simultaneous PLIF/PIV imaging of a lift-off swirling flame under acoustic forcing Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-10-14 Xunchen Liu; Sirui Wang; Guoqing Wang; Liangliang Xu; Lei Li
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Time-resolved thermographic analysis of the near-wall flow of a submerged impinging water jet Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-10-16 Ekaterina Koroteeva; Anastasia Shagiyanova; Irina Znamenskaya; Nikolay Sysoev
Time-resolved infrared thermography through infrared-transparent windows provides a novel measurement approach for non-invasive quantitative analysis of near-wall fluid flows. Here, we apply this approach to study a water flow induced by an axisymmetric submerged impinging jet in the immediate vicinity of the impingement plate. The variations in thermal radiation emitted from a thin near-wall layer
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Experimental study of droplet impact on superheated cylindrical surfaces Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-10-06 Chunfang Guo; Yanjun Sun; Danyang Zhao
In this study, droplet impact dynamics on superheated cylindrical surfaces are investigated experimentally, through high-speed imaging. The outcome regimes of impacting droplets observed in the experiments are mapped and described. Four distinguishable regimes are identified, namely rebound-transition boiling, rebound-film boiling, breakup-transition boiling, and breakup-film boiling. In addition,
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Verification of quantitative infrared thermography heat-flux measurements Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-10-20 Jens A. Rataczak; Carson L. Running; Thomas J. Juliano
Stagnation-point heat flux was measured on 7° half-angle circular cones with spherical nose diameters of 5, 10, and 25 mm using infrared thermography in hypersonic flow. All models were machined from polyether ether ketone (PEEK). A nominal freestream Mach number of 6 with varying initial stagnation conditions allowed for testing at length Reynolds numbers based on nose diameter ranging from 5×104–5×105
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Experimental study of swirl-stabilized turbulent premixed and stratified LPG/air flames using optical diagnostics Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-10-19 Dhanalakshmi Sellan; Saravanan Balusamy
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Experimental study on electrohydrodynamic atomization (EHDA) in stable cone-jet with middle viscous and low conductive liquid Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-10-07 Qisi Wang; Zhentao Wang; Shiqi Yang; Bin Li; Huibin Xu; Kai Yu; Junfeng Wang
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3D surface of an unstable hydrogen–air flame Exp. Therm. Fluid Sci. (IF 3.444) Pub Date : 2020-10-06 Grigory Bivol; Andrey Gavrikov; Victor Golub; Artem Elyanov; Vladislav Volodin
Small scale experiments examining the propagation of a hemispherical flame in a hydrogen–air mixture were performed under conditions of constant pressure. The shape of the propagating flame front in a 15% hydrogen–air mixture was reconstructed with the use of near-infrared imaging. The wrinkled flame surface was restored from experimentally obtained two-dimensional IR photographs using data on the
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