An experimental study on the flow characteristics of an array of finite-span Synthetic Jets (SJs) issuing at different conditions in a quiescent ambient was carried out by means of hot-wire and phase-locked planar Particle Image Velocimetry measurements. The actuator comprises twelve slots with aspect ratio 15 fed by a common resonant cavity and off-centered from the axis of the cavity. The frequency

The occurrence of the slug flow pattern is frequently detected in the petroleum industry. Theoretical and experimental works on the complex behaviour of this flow pattern are abundantly found, and their aim is to advance the state-of-the-technique on the behaviour of this kind of flow. The goal of the present work is to provide experimental data collected in five probing stations with resistive sensors

This paper focuses on investigating the dynamic behaviour of foam flows, including flow regimes, their transitions and pressure profiles in relation to foam characteristics (foam holdup and wetness) at different surfactant concentrations (0-500 ppm). The experiments cover a wide range of gas and water flowrates in a 4.3 m long vertical acrylic pipe with 44 mm internal diameter. Flow regimes and their

Studying the influence of a single air bubble on the noise intensity of cavitation bubble collapse has great significance for understanding the mechanism of air entrainment to alleviate cavitation in hydraulic engineering. A cavitation bubble is generated by an underwater low-voltage electric discharge device and interacts with a rising air bubble. Only the cases where the cavitation bubble centroid

Geometrical modifications in microchannel geometry intended towards mitigation of flow instabilities generally results in increased pressure drop across the microchannel heat sink. To overcome this, stepped microchannels configurations with combination of narrow bottom (aspect ratio: AR = depth/width >1) and wider top (AR<1) part are investigated and their flow boiling performances have been compared

The flow pattern of gas–liquid mixtures across a single-orifice plate in horizontal pipes, in particular the change in flow patterns downstream of a single-orifice plate (DSOP) when the upstream is in a common intermittent flow, has not been elucidated hitherto. In this study, a visualization experiment was performed using air and water as the gas and liquid phases, respectively. The effects of superficial

Recirculation zone dynamics in a cavity located in the bottom wall of a water channel with height h = 0.3 mm and width b = 0.9 mm are investigated experimentally and numerically. A microparticle image velocimetry method and instrumentation are used for the experimental determination of flow velocity distribution and reattachment pattern with Reynolds number from ReDh = 30–2000, cavity length to depth

An experimental study was performed to investigate the effects of nozzle spacing between twin rectangular jets on the non-linear momentum interference and spatial evolution of large-scale flow structures. Five test cases of different spacing ratios (S/de = 1.8, 2.8, 3.7, 5.5 and 7.3) were examined. Two-point correlation, joint probability density function and swirling strength were used to characterize

Utilization of vertical electric field can depart water droplets from superhydrophobic surfaces, which has significant application in microfluidic and self-cleaning. Here, we studied the droplet jumping dynamics behavior in the electric field, which was applied by pulsed and direct current (DC) power. The results indicated the droplet can jump more rapidly under the pulsed electric field. Compared

Visualization-based nucleate pool boiling experiments are carried out on different sizes of square micropillar array surfaces (SMAS) and plain surface using deionized water as working fluid at atmospheric pressure. The quantitative measurements of the bubble dynamics, including the nucleation site density, the bubble departure diameter and the frequency, are obtained using a high-speed camera with

Fiber optic sensors offer a new and unique way to detect and analyze phase transitions, due to their small thermal mass and inert material. This paper presents and demonstrates a dual-sensor system to detect and analyze phase transitions in pure water and aqueous ethanol mixtures. With a multi-mode interferometer based on a thin-core fiber, and a fiber Bragg grating sensor, it is possible to differentiate

The flow around three simplified models of side-view mirrors for automobiles is experimentally investigated by means of Robotic particle tracking velocimetry (PTV). The measurements are performed coupling a coaxial volumetric velocimeter with time-resolved three-dimensional (4D) Lagrangian Particle Tracking (LPT) data analyzed with the Shake-The-Box (STB) algorithm. Helium-filled soap bubbles were

CO2 sequestration in saline aquifers is considered to be a promising method for climate mitigation. Studies of the subsurface flow mechanisms of CO2–brine are important for evaluation of sequestration potential and security. However, this process is complicated by the intrinsic heterogeneity of reservoir rocks. The main objective of this study was to identify CO2 distribution and saturation related

The sprays produced by spill-return pressure-swirl atomizers are strongly dependent on the nature of the internal fluid dynamics. Several spill-return atomizers were compared in terms of the spatial and temporal behaviour of the internal air-core, liquid sheet thickness and its perturbations. The only difference amongst the test configurations was the geometrical arrangement of the spill-line (SL)

This study experimentally investigated the heating process of an axially induced cold gas stream in a swirl tubular flame established through tangential fuel/air pre-mixture injection, aiming to clarify the effects of swirl motion on the heat and mass transfer enhancement. Tubular flame burners with geometry swirl numbers (S) of 0.35 to 1.4 were employed in addition to a conventional slit-type burner

The knowledge of wave structure and velocity is of great importance to the prediction of annular two-phase flow phenomena. Given that most existing experimental studies focus on the low liquid flow rate, the goal of this study is to extend the understanding of wave characteristics to high liquid flow rate annular flow, i.e. wispy annular flow. Conductance film thickness probes have been used to measure

The present investigation is based on the experimental analysis of heat transfer distribution and friction features of a solar air heater that has a rough absorbent surface with winglet type vortex generator has been made using liquid crystal thermography technique. The RrGgBb (red, green and blue) colour pattern obtained because of temperature variation which can be visualized by the captured image

Researchers around the world have proposed different methodologies for flow-pattern identification in multiphase flows. The most common explored techniques are based on optical imaging, pressure fluctuation, electrical impedance, radiation absorption, and ultrasound. Because the ultrasonic technique is relatively low in cost, easy to conduct, accurate, nonintrusive, and suitable for opaque systems

The accurate measurement of gas-liquid flow is becoming increasingly significant in the oil and gas industry. Over-Reading (OR) model is the foundation for the gas-liquid flow measurement using Venturi. In this paper, a new OR model based on the form of Chisholm model for horizontal Venturi has been developed. The relationship between entrainment rate and OR in the throat of Venturi has been considered

This study experimentally examined the response of a lean premixed methane/air swirl tubular flame to the longitudinal acoustic perturbations. Experiments were conducted by varying the acoustic frequency (f0), acoustic power (P0) and inlet air flow rate (QA) to systematically study the acoustic-excited flame dynamics, including the flame stability, flame structure, heat release rate and acoustic pressure

Optimization in the geometry structure of the pulsating heat pipe (PHP) may provide an effective method to improve the heat dissipation capacity. In this study, tandem tapered nozzles are proposed to promote the unidirectional flow in a three-dimensional (3D) closed-loop PHP (CLPHP). For comparison, two six-turns CLPHPs comprised of 12 glass tubes with a 2 mm inner diameter (ID) and 13 silicone hoses

Image analysis technique is a common method to measure the void fraction and bubble size distribution in the bubbly flow. However, the image recognition algorithm will become invalid finally when the the projection overlaps of bubble become more heavily. In this paper, a new approach on three-dimensional (3D) reconstruction and parameters measurement of overlapping bubbles is developed based on laser

In this work, we present an approach to reconstruct high-resolution flow velocity or scalar fields from sparse particle-based measurements such as particle tracking velocimetry, thermographic phosphors or pressure-sensitive particles. The proposed approach can be applied to any of those fields; without leading its generality, it is hereby assessed for flow velocity measurements. Particles allow probing

The ultrasonic heat transfer enhancement has a strong dependence on the sound intensity. The higher the local sound intensity is, the better the heat transfer enhancement achieves. Therefore, a focused ultrasonic field is proposed in cavities with elliptical cross-section based on interference criterion and standing wave criterion. To design a cavity with focused ultrasonic field, sound source and

The water exit problem is a fundamental problem in fluid dynamics, and the behavior of the air–water interface and the energy transition of an object exiting water have not been thoroughly investigated. In this study, a solid sphere with a density of 2.64×103kg/m3 and diameter of d=25.4 mm was launched vertically upward in water toward the air–water interface. The motion of the sphere and the behavior

To achieve high efficiency and low pollutant emissions with large spark ignited gas engines, operation at high excess air ratios and high turbulence levels in the combustion chamber is necessary. Under these severe boundary conditions, it is a great challenge to reliably ignite the air-fuel mixture and keep cycle-to-cycle variation of the combustion process within reasonable limits. This paper investigates

Fast-response coaxial surface junction thermocouples have been used to measure time-resolved stagnation temperature of the Mach 6 flow produced by the University of Southern Queensland’s hypersonic wind tunnel, TUSQ. The piston compression and the nozzle expansion of the test gas were found to be approximately isentropic for the first 65 ms of flow. Thereafter, the stagnation temperature reduces from

During droplet impact on thin wall-films, a liquid lamella, the so-called ‘crown’, expands radially and vertically away from the impact point. This phenomenon is often associated with the growth of fingers at the crown rim, leading to the fascinating crown-type splashing. The present study reports an experimental investigation on droplet impact on wall-films, where the droplet and wall-film are made

The present work systematically investigates the effect of cavitator mounting strut and cavitator shape on the ventilation demand to form and sustain a ventilated supercavity under different flow conditions. Three cavitators of different shapes (i.e. 2D cavitators including triangle and disk shape, and 3D cone-shaped cavitator) with the same frontal area are employed for the experiments. The cavitator

This study examined improvements to evaporation and conduction heat transfer from the use of a multilayer graphene-coated surface. Two surface modification methods, namely the chemical vapor deposition and sol-gel methods, were used to apply multilayer graphene onto copper plates. The results indicated that compared with a plain copper surface, the graphene-coated surface provided superior performance

The atomization characteristics of a commercial spillback hydraulic nozzle were investigated in terms of droplet sizes, velocities, trajectories and spray angles. To replicate the fuel spray of a commercial auxiliary marine boiler, an experimental setup was designed and used to atomize water-glycerol solutions with various viscosities. Droplet size, velocity, position and shape were obtained with a

This work investigates the geyser boiling phenomenon (GBP) occurring in a passively cooled, two-phase loop thermosyphon. The influence of the heating load, working fluid, fill ratio, and the evaporator surface design on thermosyphon thermal performance and the associated instabilities were studied. The effect of working fluid was compared using deionized water and ethanol. Fill ratios ranging from

A new line-of-sight optical diagnostic technique was developed for measuring species’ concentrations using broadband (band-pass) filtered natural emission of species (FNES). The unresolved problem in measuring a species’ concentration via FNES is the overlap of different species at certain emission wavelengths, which makes the measurement of a single species problematic. A solution is proposed in this

A vortex tube is a device which separates an incoming compressed gas into cold and hot streams. The experimental results reported by various researchers were used as a database to obtain a correlation. A term called Rutika-Ramakrishna Correlation Factor or RR Correlation Factor is coined which correlates the parameters such as ratio of length of the vortex tube to the diameter of the vortex tube, ratio

Understating two-phase flow through flow restricting orifices is critical in evaluating the piping degradation mechanisms in nuclear power generation systems. Characterizing the instantaneous changes of the two-phase local parameters across flow restricting orifices is critical in evaluating the piping structure dynamics. A multi-channel void fraction sensor was developed to investigate the effect

Subatmospheric pool boiling heat transfer was investigated experimentally. At low vapor pressure, the static head of the liquid column induces a non-negligible pressure gradient. This results in a local pressure-induced subcooling that makes the case of boiling at low vapor pressure with a high level of liquid a particular case of subcooled boiling. The experiments were conducted for variety of working

In this work, experiments were carried out to compare the phase separation performance of double branching T-junction with that of single branching T-junction. The inlet and outlet branches of double T-junction were arranged horizontally with the inner diameter of 8 mm. R134a was used as the working fluid. The inlet mass flow rate (mass flux) was set at 10, 15, 20, 25 g s−1 (199, 298, 398, 497 kg m−2

This study concerns the effect of non-thermal plasma discharges on simulated biogas (mixture of CH4 with 80–20 vol% CO2) combustion at atmospheric pressure in synthetic air or synthetic air enriched by oxygen. The plasma-assisted, premixed combustion was performed in a porous-plate burner with dielectric barrier discharge microplasmas driven by nanosecond high-voltage pulses at 3 kHz and 10 kHz repetition

To explore the influence of the non-uniform inlet velocity profile of the bluff body on flame stabilization, PIV measurements are carried out to investigate the characteristics of the flow field at 300 K and 0.101 MPa with seven velocity profiles, including four-velocity peaks, h/H, and three non-uniformities, δv. The experimental results indicate that the recirculation is approximately symmetric with

An experiment investigating the second-mode instability on the sharp cone with a small angle of attack has been conducted. The fine structure in the boundary layer has been visualized by the Nano-tracer-based Planar Laser Scattering(NPLS) technique. The “rope-like” second-mode waves are found to still be the dominant structures before the transition of the boundary layer at 1° angle of attack and the

Flow mode transitions on metal foam wrapped tubes in shell and tube heat exchanger may affect the condensate characteristics obviously because the condensate inundation severely depends on the flow mode. In the present study, the flow mode transitions were experimentally investigated by observing the flow modes on metal foam wrapped tubes and determining the Reynolds numbers (Re) of flow mode transitions

An experimental study was conducted on flow around two-dimensional, square-backed bluff bodies in the presence of a ground plane. Two frontal geometries were tested: one with significant leading-edge separation and one without. The extensive leading-edge separation was found to induce significant asymmetry in the time-averaged wake. One-sided shedding from the top trailing edge was found to occur in

An experimental study using pressure-drop and μ-PIV measurements was undertaken to better understand the fluid flow characteristics in different flow regimes within randomly packed microscale porous beds with different sized spheres. Three sintered glass samples were made with glass spheres having a mean diameter of 170 μm, 430 μm and 710 μm by slightly sintering them between two glass slides, forming

The structure and instability characteristics of non-adiabatic fuel-rich n-butane/air cellular flames on McKenna burner were experimentally investigated at atmospheric pressure. Planar Laser Induced Fluorescence (PLIF-OH and PLIF-CH2O) flame diagnosis technology was utilized to probe the flame structure under varied equivalence ratio and inflow mixture velocity respectively. Results show that, the

Safety concerns due to the highly unstable nature of boiling during the transition from the nucleate to the film boiling regime has limited investigations on this topic. Here we perform simultaneous characterization of the thermal, acoustic, and the bubble visualization data during the transition boiling regime. We show that the key features missed due to the high latency in the thermal data are captured

Correlations to predict the hydrodynamic and thermal entrance lengths in a smooth horizontal tube heated at a constant heat flux are often restricted to forced convection conditions. The reason being that most scholars do not distinguish very well between forced and mixed convection conditions. Furthermore, most correlations have been developed for hydrodynamically fully developed and thermally developing

Recently, several attempts have been made to implement electrospray for electrostatic precipitators (EPs) to reduce water consumption and prevent dust from being rescattered from dry EPs. In particular, the electrospray droplet size in EPs should be sufficiently large to collect dust in the exhaust gas flow, which requires a considerably larger electrospray flow rate than that required for typical

The future technological horizons for engineering applications (Automotive, Energy, Bio-Engineering) require the use of limited size heat exchangers with high efficiency. In the present work, the flow field in small scale channels of different geometries is investigated experimentally using µPIV (micro Particle Image Velocimetry) and thermal measurements. The Reynolds number in the channels is changed

The formulation of the total force exerted by magnetic fields on ferrofluids has historically been a subject of intense debate and controversy. Although the theoretical foundations of this problem can now be considered to be well established, significant confusion still remains regarding the implementation of the associated expressions. However, the development of future applications in low-gravity

In hilly terrain pipelines, gas–liquid slug flow usually forms in the low-lying elbow and develops in the inclined ascending pipe at a low superficial liquid velocity and influences the effective and safe natural gas transportation. The surfactant additive has a significant effect on this flow and promotes the liquid drainage in hilly terrain pipelines. To further understand the interaction mechanism

A visualized experimental system is designed and constructed to study the bubble behaviors on the micro-orifice in liquid layer. The test section is performed in a rectangular duct of 0.27 m × 0.006 m × 0.012 m, and the air is injected from an orifice with 0.49 mm in diameter. The gas flow rate is in the range of 0.3–60 ml/min, while the corresponding Reynolds number is ranged from 0.87 to 173.18.

This study experimentally investigated the boiling flow patterns, local heat transfer coefficients, and pressure drops of R32/lubricant oil mixtures flowing inside a horizontal multiport extruded tube having rectangular minichannels. The experiments were carried out in a mass flux range of 50–400 kgm-2s-1, heat flux range of 5–40 kWm-2, and oil circulation up to 3.7 wt% at an evaporation temperature

In the present study, we place a short splitter plate onto the upstream side of a circular cylinder to modify its incoming flow conditions and the wake-vortex patterns and to attenuate the aerodynamic forces. Wind-tunnel investigations are performed at a Reynolds number of Re = 2.66×104. Special interests are paid to the length sensitivity of the rigid splitter plate. The 2D particle image velocimetry

In this work, we experimentally study the acoustic response of water drop impacts onto a variety of surfaces using both audio recording and high-speed imaging. Audio recordings of the airborne sound emitted by single drop impacts on deep pools, thin liquid films, and dry aluminum and masonry surfaces are captured in the laboratory. Longer audio recordings are also collected for natural rainfall on

To divert water from rivers, several structures can be employed. Bottom intake is one of the hydraulic structures which is generally used for this purpose in steep streams. Bottom racks are associated with the problems such as deformation, corrosion, vibration and clogging by foliage, sediments, and freezing. A new type of bottom intakes is introduced to overcome these difficulties in which the racks

In recent years, microchannel water flow boiling has demonstrated excellent heat removal capabilities, particular for nuclear reactor safety utilities, ranging from mini-scale cooling devices to chemical industry plant purposes. Of particular interest is cooling technology using water as the primary refrigerant. This paper presents the results of an experimental investigation into the water boiling

The cavitation erosion characteristics of self-excited cavitating waterjet produced by a nozzle with various lip geometries were investigated. The cavitation erosive intensity was estimated by the mass loss of pure aluminum specimens and the sound press level of under the optimum standoff distance. The power spectrum density of noise and the surface profiles of the specimens were studied to uncover

The effect of fuel temperature on the erosion intensity in micro-channels for different fuels like calibration fluid ISO 4113 and dodecane is investigated. A high-pressure closed loop test bench for fuels under elevated temperatures up to 160 °C is used to erode micro-channels made of Al 99.0 at a maximum pressure of 500 bar. The evaluation of the erosion intensity reveals a temperature of maximum

This paper studies the crosswind aerodynamics of an interior train and flat box bridge-deck system via a series of wind tunnel experiments in wind angle of attack α = [−12°, 12°]. Aerodynamics of the train- and bridge-only models is measured as benchmarks under similar conditions. Upon comparing with the train- and bridge-only cases, the lateral aerodynamic interference between the train and bridge-deck