Droplets impacting on superhydrophobic surfaces with submillimetric or millimetric macrotextures can rebound completely after a short contact time, which is of practical importance in applications like self-cleaning and anti-icing. Many researches have been done on the centered impact, but the off-centered impact is rarely studied, even though it occurs more often. In the present work, we investigate

Sloshing refers to the motion of the free liquid/gas interface inside a partially filled container subjected to an external excitation with a consequent motion of the system center of gravity. Several parameters related to the fluid container, the fluid properties, the excitation levels, and the gravitational environment govern this phenomenon. Moreover, it is a significant cause of disturbance in

The effect of drag reducing riblets on the flow structure was examined experimentally for a turbulent boundary layer at Reθ = 9890 and riblet spacing s+ = 13.4. Trapezoidal riblets were used, which were attached to the water tunnel wall as a coating. Force measurements were performed to quantify the amount of drag reduction. Then, the mechanism underlying this reduction was investigated by stereo-PIV

Two phase flow is of great interest in chemical and petroleum industries, and multiphase pipe flow models with closure relationships require experimental data for their development and validation. However, only little experimental information is available for slightly upward inclined pipes. Experimental investigations of single elongated bubble in marginally upwardly inclined pipes less than 10° have

This paper describes an experiment conducted to investigate thermal distribution during liquid atomization. An infrared camera was used to measure liquid temperature changes over time during atomization. Effects of device frequency, input power, and liquid viscosity on thermal distribution during surface acoustic wave (SAW) atomization were investigated, both experimentally and through simulation.

A multi-channel gliding arc (MCGA) plasma was used to enhance ignition and combustion of ethylene fuel in a cavity-based scramjet combustor with an inflow speed of Ma = 2.92. Simultaneously electro-optical diagnostics were conducted to show characteristics of the MCGA-enhanced ignition and combustion, as well as simultaneous schlieren and CH* emission images. The voltage and current measurements demonstrate

Experiments were preformed to measure the mass and size of secondary droplets splashed during liquid jet impingement onto a horizontal solid surface. To explore the effects of liquid hydraulic properties such as viscosity and surface tension, pure water, two aqueous solutions of glycerin, and two aqueous solutions of ethanol were used as the test solutions. Using the experimental data accumulated in

This research study investigated the three-dimensional nature and characteristics of buoyant thermals in the mixed convection turbulent boundary layer. Thermals were visualized using a multi-plane flow visualization technique. Experiments were performed in a variety of conditions where the bulk Richardson number was varied to cover a range describing both inertia dominant flow dynamics (RiL=0.05) and

This work presents a data-driven approach for the identification of relevant flow features and the breakdown of their contributions to unsteady forces in flapping airfoils. The method exploits the correlation between simultaneous flow-field and force measurements. The Extended Proper Orthogonal Decomposition of flow fields and force is employed to identify relevant flow features and to ascertain their

This paper presents the experimental results obtained in a directly irradiated fluidized bed. A bed with a diameter of 314.76 mm was filled with SiC particles and directly irradiated from the top with a beam-down reflector with a 2 kW Xe-lamp. The study examines the influence of the bed height and airflow rate on the temperature distribution over the top surface of the bed (where the concentrated irradiation

To control the wake flow around a wall-mounted cube, passive control is performed by drilling a front inclined hole (FIH) from the front surface to the free end of the cube. To study the control features and mechanism, controlled and uncontrolled cubes are experimentally investigated. A circulation water tunnel is used to perform PIV measurements, where the Reynolds number is ReD = 11550 based on the

There is a significant decrease in flow boiling CHF when the inertial force of the fluid is not large enough in microgravity, but this tendency decreases with the increase of the inertial force. In the present study, the critical heat flux (CHF) of subcooled flow boiling at different gravity levels on smooth silicon surfaces was investigated. The working fluid is FC-72, with the subcooling of 15 K

The effect of surface hydrophobicity on the air-water two-phase flow pattern transition was experimentally investigated. Experiments and the two-phase flow visualization were carried out in a hydrophobic polymer tube (4.76 mm ID). The tube material is fluorinated ethylene propylene (FEP) with a hydrophobic surface, and the static contact angle of a water droplet on a smooth surface is 97.28°. The channel

Because wire-meshes have a great potential application for designing high-efficient heat and mass transfer systems, a deformable bubble of Re ~ 800 rising in still tap-water near a vertical mesh of different porosity is studied using a high-speed shadowgraphy apparatus including two mutually perpendicular projections. We focus on the effect of the boundary conditions with three types of meshes (Mesh-L

The impingement dynamics of a promising ionic liquid absorbent, namely, 1-ethyl-3-methylimidazolium acetate ([EMIm]Ac) in droplet falling film flow modes on heated porous surfaces in absorption refrigeration were investigated experimentally. The influences of impact velocity and surface temperature on the ionic liquid droplet spreading diameter, dynamic contact angle, spreading height, and residual

In this paper, we have performed an experimental study of the effect of changing the surface tension of the water in vertical annular concurrent two-phase flow (air + liquid) by adding small amounts of 1-butanol to the liquid phase. Adding small amounts of this chemical compound diminishes the surface tension of the water, while the dynamic viscosity remains practically unchanged. A set of experiments

The flow fields around different pile groups (multiple circular cylinders) mounted vertically on a flat bed were experimentally studied by using Particle Image Velocimetry (PIV). The characteristics of the horseshoe vortex (HV) in front of the pile groups were systematically investigated, including its time-averaged flow topology and instantaneous evolution, and the associated bed shear stress. The

Two-phase flow characteristics of gas injection through a slot nozzle into a liquid bath were studied experimentally. A dual-sensor electrical probe measurement system was used to obtain the distributions of multiple two-phase flow parameters. Measurements were conducted under various gas flow rates, nozzle widths and at different planes vertical to the slot nozzle. It is found that the void fraction

This paper examines a common hypothesis in the design of internal combustion engine exhaust lines, namely that the ratio of the total pressure drop across the line to the inlet dynamic head should be a function only of the Reynolds number. While incompressible flow theory, provided that some simplifications are considered, is often used in support of this hypothesis, detailed experimental verification

Droplet size distribution during ultrasonic atomization was investigated by laser diffraction based on two phenomena—capillary waves and cavitation. The former was visually illustrated using the photographic method, and the latter was examined by the potassium iodide decomposition rate test and Particle Image Velocimetry technique. This study also analyzed the effects of operating ultrasonic parameters

In order to understand the energy transfer mechanism and the coupling relationship between the interface evaporation and thermocapillary convection at low vapor pressures, a series of precise temperature measurements were conducted in a water-filled annular pool with radial temperature gradient. The initial depth of water in the annular pool is 10 mm and the temperature difference between the inner

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

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

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

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

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 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

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

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

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

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

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

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 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

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

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