The paper investigates the impact of single drops of water, Jatropha biodiesel (JBD), and their emulsions of varying composition on an inclined surface to clarify the influence of emulsification and impact velocity on the residence time (TR) above Leidenfrost temperature (TL). Results show that though the impact is inclined, the process solely depends on the normal component of the impact inertia.

Every year the European community interested in the broad branch of science dealing with multi-phase disperse flows convenes at ILASS conferences. The scientific and industrial communities share ideas, information and technical advances in liquid atomization and spray systems. The 2020 European ILASS conference was planned to be held in September in Israel. The fast spreading COVID-19 pandemic lead

The flow and cavitation phenomena inside nozzle sac play an important role in the fuel atomization process, especially at the end of the injection, which may cause high-temperature gas ingestion consequently leading to coke formation inside the orifice. It is of great difficulty to reveal the flow and cavitation morphology inside fuel nozzles during the fuel injection process since the nozzle sac is

This paper investigates the linear stability of a liquid jet exposed to subsonic crossflow with aluminum particles and surfactant. A dispersion relation for the disturbances at the interface is obtained. The characteristics of metal particle are shown in the expressions of liquid density, viscosity and surface tension. The results reveal that the non-dimensional surface tension gradient and surfactant

Low flow rate spray devices have many diverse engineering applications ranging from low energy burners to medical inhalers. Conventional atomizers are unsuitable for low injection rate applications, owing to inefficient atomization. Coaxial flow-blurring injectors have shown the capability of spray formation at extremely low injection rates, although challenges remain with respect to maintaining a

This article describes a series of modern developments carried out by the inkjet community in its quest to improve material compatibility, printing quality, and reliability. Recent progresses in rheology have advanced our understanding of liquids at the time scales that are characteristic of inkjet printing processes. As a result, microsecond rheology now permits the formulation of inks with tailored

This paper presents experimental results on disintegration of initially unatomized extinguishing liquid arrays in the free fall from a variable height. In laboratory conditions, the discharge height varied in the range of 0.5–3 m, and in field tests it was 3–15 m. The initial volume of unatomized liquid varied in the range of 0.05–1 l. The following compositions were considered: water without impurities

The accurate prediction of multiphase flow phenomena is associated with high computational costs. Among many different numerical approaches that have been employed to reduce computational resources is the so-called Viscous Potential Theory (VPT) pioneered by D. D. Joseph. The present method builds on this theory and extends it to include a generalized form of the Viscous Pressure Correction for VPF

In this work, based on experimental measurements, a fundamental and theoretical model for the collision and coating of free movable solid particles with smaller droplets will be developed. The decisive advantage of the experimental setup is that the droplet-particle collisions are investigated under quasi-instationary conditions. By means of imaging measurement techniques, the collision of the single

An experimental-phenomenological study was conducted to explore single droplet and droplet-droplet nucleation, transition, and film boiling characteristics. Major differences were identified for the different boiling processes. For a single droplet impact, we identified 3 evolution stages: temperature rise, nucleation boiling incipience, and bubble growth. For droplet-droplet collision prior to nucleation

X-ray phase contrast imaging is conducted at 90,517 Hz on a fuel spray to characterize the breakup of the bulk fuel into ligaments and indiv¬idual droplets in a single-sector, swirl-stabilized combustor under reacting conditions. Phase contrast imaging is used to qualitatively assess spray breakup for two fuels: Jet-A, which represents a normal viscosity fuel, and a blend of JP-5 (64%) and farnesane

The spray developments are mostly influenced by the flow characteristics inside a diesel nozzle orifice. In this paper, an experimental visual system is installed with transparent nozzles. This test rig is used to scrutinize the effect of enlarged scales and continuous bubbles on the cavitation phenomena in CI nozzles. The variation of discharge coefficient with the cavitation number under two cavitation

We conducted CFD simulations to improve the currently available inkjet technology. This study was motivated by the general problems related to lack of precision control over the quality of droplets emanated from the industrial atomizer sprayers and growing needs for higher quality droplets in the coating industry. We focused on an ultrasonic pulsation atomizer (UPA) capable of producing mono-dispersed

As a key parameter for describing the microscopic characteristics of fuel spray, the Sauter mean diameter (SMD) is widely applied for evaluating the spray effect. Researchers have proposed several formulas for predicting the SMD under different experimental conditions. However, there are two main limitations. First, only the physical properties of the fuel and initial injection parameters are considered;

The atomization and mixing processes of fuel in crossflows are among the important aspects of research into Rocket-Based Combined-Cycle (RBCC) engine technology. In this paper, the atomization characteristics and penetration height of the kerosene jet in crossflows are studied. The influences of the orifice diameter, number, and arrangement, the injection pressure drop of fuel, the orifice diameter

The three-dimensional in-nozzle flow of two single-hole injector nozzles are investigated based on the improved Multi-Fluid-Quasi-VOF solver coupled with the LES approach in the OpenFOAM framework. The cavitation model is also included to study the effect of the nozzle structure on the cavitation inside nozzle and primary breakup. The continuity equations and the momentum equations are reformulated

While diagnostics exist for quantifying droplet fields in an atomized spray, direct imaging is needed to quantify and characterize the interfacial instabilities responsible for droplet generation. To study these interfacial instabilities in high-pressure sprays used in direct injection engines, resolving power of approximately 1 um is required. Imaging systems must also work around high-pressure optical

Identifying the regime of a liquid jet is necessary to determine the physical mechanisms causing breakup and consequently how to model the jet. Existing regime diagrams are based on a small amount of data classified by superficial visual characteristics, making these diagrams too inaccurate to reliably determine the correct regime. A more accurate regime diagram is developed using primarily a large

In this work, we use direct numerical simulation through a volume of fluid solver with adaptivemesh refinement to analyze the atomization of a pulsating round liquid jet with a narrow length-scale range configuration. We propose three grid sizes based on characteristic scales we estimate from the deformation and fragmentation processes of this problem. We compute drop statistics and general spray features

In this work we investigate moderately underexpanded n-hexane jets in a supercritical environment with respect to the injectant. At supercritical chamber pressure and constant nozzle pressure ratio of NPR ≈ 5.6, we systematically increase the reduced injection temperature from Tinj = 1.06−1.18. Our experiments comprise multiphase and single-phase injections. The latter expand close to the Widom line

Alternative jet fuels have a high potential to reduce emissions in aviation. A big difficulty for their introduction is the costly and lengthy assessment of fuel effects on combustion performance. In the present work, the evaporation of free-falling droplets of realistic size (D ≈ 80 μm) in a well-defined vertical laminar heated flow is studied experimentally and numerically. Measurements of droplet

The objective of this study is to investigate spray characteristics such as liquid penetration and vapor penetration of methanol sprays under evaporative conditions. The spray characteristics were measured in an optically accessible constant volume chamber filled with nitrogen at pressures and temperatures of relevance to engine conditions. Injection pressures of 200 bar, 300 bar, 400 bar, and 480

We experimentally investigate collisions between a regular stream of droplets and a continuous liquid jet. In this work, the effects of viscosity on the outcome of immiscible drop-jet collisions are studied. To do so, a broad variation of liquid viscosity of both the drop and the jet liquid is considered. Two basic liquid types are used, including three aqueous glycerol solutions for the drop and three

Predicting drop size has remained an important aspect in the development of Lagrangian-Eulerian (LE) and other spray models. In the present work, the importance of drop size and spreading angle are evaluated by employing high-fidelity atomization simulations using an algebraic volume of fluid (VoF) approach (InterFoam). The process begins by extracting an axial drop size profile (D32VoF) from VoF results

When it comes to quality and efficiency, droplet diameters have a substantial impact on paint application processes. To determine droplet diameter distributions, Malvern-type laser diffraction and phase Doppler anemometry are common techniques. This has changed since 2014, as SpraySpy-type time-shift instruments became available. In this study, an industrial spray-painting atomization process using

In this work, a combination of a spin-coating device and a noninvasive planar laser-induced fluorescence technique is realized for characterization of the interaction of sprays with thin wall films. This system enables investigation of resulting film topography and concentration fields after interaction of binary systems (different liquids for spray and film) in dependency of operating conditions.

Due to the longer auto-ignition time with liquid fuels compared with hydrogen, understanding the interaction of shock waves with sprays and subsequent vapor mixing is significant for designing ramjets/scramjets with liquid fuel sprays. In this study, an Eulerian-Lagrangian framework is developed based on the OpenFOAM platform. In this solver, detailed multicomponent transport models for Eulerian gas-phase

In flame spray pyrolysis (FSP), the understanding of the atomization and spray formation of the coaxial atomizer is a key step to control the mixing of reactants, and precursor release, as well as nanoparticle formation and growth mechanisms. The drop size and drop dynamics of fuel/precursor mixtures are relevant parameters to control the particle synthesis via gas-to-particle conversion for tailoring

Polyoxymethylenether (OME) is a promising fuel for CO2 reduction and a prospective change in the transportation sector. To see the effects of different fuel properties on mass flow rate and mixture formation, OME 3, OME 4, and a mixture of OME 3 and OME 4 (called OME Mix) are compared to European standard diesel fuel. They are investigated for a passenger car and two different commercial vehicle injectors

An improved simplified theory of polydisperse spray flame ignition is presented for the case of a semi-infinite homogeneous region of air and fuel droplets subjected to heat flux by an infinite slab. Our previous models used a basic assumption that the evaporation commences simultaneously for all droplets at a given prespecified evaporation temperature, irrespective of the size of the droplets. In

Swirl injectors are widely used in aerospace propulsion systems because they exhibit high mixing and combustion efficiencies of the propellant. Unlike a single liquid injector, a coaxial gas-liquid swirl injector, in which droplet breakup is accelerated by the gas flow, depends on the droplet generation mechanism at the beginning of the mixing process. High-velocity gas flows affect droplets and can

Due to current and future environmental and safety issues in space propulsion, typical propellants for upper stage or satellite rocket engines such as the toxic hydrazine are going to be replaced by green propellants like the combination of liquid oxygen and hydrogen or methane. The injection of that kind of cryogenic fluid into the vacuum atmosphere of space leads to a superheated state, which results

Swirl injectors are widely used in aero-engine combustors. Their atomization characteristics determine the ignition performance and combustion efficiency. However, little research has been conducted on their atomization characteristics at low temperatures. To explore the effect of fuel temperature on injection characteristics, this article describes an experiment in which the fuel was cooled and the

Fuel injector design has a substantial influence on the performance and emissions of direct injection engines. To date, large eddy simulations coupled with a single-fluid mixture modeling approach have shown great success in evaluating the complex interplay among injector design, fuel properties, and operating conditions on the injector performance. However, this simulation approach is too computationally

The implementation of high-pressure oxy-fired systems presents unique challenges to burner and combustor design. For the same throughput as an atmospheric or low-pressure system, high-pressure reactors have a much smaller footprint, and consequently the injectors, mixers, and combustion chambers are reduced in size. Adequate burner performance, heat dissipation, and solids handling are therefore challenging

Nozzle hole diameter and injection pressure have a significant effect on diesel spray combustion and emission characteristics. The current work presents an experimental and computational study of diesel spray under nonevaporating and evaporating spray conditions, considering the effects of hole diameter and rail pressure. Three single-hole injectors with hole diameters of 0.101 mm, 0.122 mm, and 0

In the present study the relation between cavitation inside a multi-hole mini-sac nozzle and the progress of the liquid jet atomization was analyzed by means of a quantitative image analysis of transient cavitation in the injector and the atomizing spray. The unsteady string cavitation forming inside the sac and wall cavitation in an orifice of a transparent three-hole injector model were captured

The temporal instability analysis on the shear layer formed by injecting nitrogen jet into the supercritical nitrogen environment was carried out. The instability solution of the supercritical shear layer was obtained by using a spectral high precision, numerical method. The real gas effect of the base flow was calculated by using the Soave-Redlich-Kwong equation of state. The dependence of the viscosity

The present study optically measures the liquid spray penetration using high-speed backlight illumination imaging in a running small-bore compression-ignition engine. This imaging technique utilizes high-power LED as a light source that is reflected on the flat cylinder head surface except the vaporizing spray region. The boundary detection of this dark region is performed to calculate the spray tip

The dynamics of spreading and recoiling of a liquid droplet after colliding with a partially wet solid surface is studied analytically. Using a mass-spring-damper analogy and based on the variational principle, the energy balance equation is developed, and a nonlinear ordinary differential equation is obtained. Predicted results are validated against the experimental data of others, and it is shown

The KH-RT (Kelvin-Helholtz-Rayleigh-Taylor) breakup and dynamic structure subgrid-scale (DS SGS) models have been widely utilized to predict the spray evolutions in diesel engines, while the prediction accuracy is highly dependent on the tunable constants. Most of the tuning efforts for both of the above models are limited to the nonevaporating conditions or specified ambient conditions with the Reynolds

Flash boiling occurs with gasoline direct injection spray at throttling, and low-load engine conditions leading to plume interactions and sprays collapse under low ambient densities. The change of fuel trajectory compared with the injector's initial design could leave an adverse effect on spray combustion quality, although flash boiling has the potential of achieving better atomization. Thus, studies

Drop impact onto inclined and moving surfaces are seen in various applications, for example, inkjet printing, spray coating, or in agriculture; droplets impact on either the surface that is moving, inclined, or a combination of both. Studies in the literature have examined the phenomenon of drop impact in isolation, either for a moving surface, or an inclined surface. Therefore, we conducted a comparative

For the past 50 years, there has been a great deal of interest in using water-based explosion suppression systems to mitigate the impact of thermal explosions and their consequential overpressures. Previous researches focused on the suppression and mitigation with sprays containing droplets 200 μm ≤ D32 ≤ 1000 μm. The present study concerns the mitigation of slow-moving deflagrations with speeds of

Coaxial atomizing sprays are used in industries from gas turbines to food processing. Spray dynamics depend heavily on the primary breakup (near-field) region. The near-field region is challenging to study because it contains thick liquid that is impenetrable to visible light. However, X-ray radiographs are capable of penetrating the dense liquid region, providing insight that is unavailable from visible

Near-field structures of pure- and aerated-liquid jets injected into Mach 2 crossflow environments were experimentally investigated at the 7-BM beamline of the Advanced Photon Source at Argonne National Laboratory using high-speed shadowgraph imaging, high-speed x-ray imaging, and pathlength-integrated x-ray fluorescence. Liquid was flush injected into a blowdown supersonic wind tunnel. Test section

A new computational procedure for simulating liquid jets in crossflows with atomization is described and demonstrated. In our previous work, the integral form of the conservation equations has been used to derive explicit quadratic formulas for drop size during spray atomization in various geometries. This formula relates the drop size with the local kinetic energy state, i.e., the velocities, so that

Correct prediction of the spray in automotive and aerospace engines remains a challenging task. In this work we present a numerical framework to characterize the spray, using both the large scale quantities, like mean liquid volume fractions, as well as small scale structures or liquid droplets. In the limit of high Reynolds and Weber number, the drop size is expected to be much smaller than can be

Droplet collisions are common to many gas-liquid systems, based on spray flows injected into a gas-vapor environment. It is customary to distinguish between roles of precollision droplets (target and projectile) in such systems. As a rule, the target droplet has slower velocity than the projectile droplet or can even be stationary. Secondary atomization of droplets through their collisions with each

The influence of the cavitation effect on the diesel engine nozzle is based on the following aspects: flow and spray characteristics, cavitation erosion on the nozzle wall, and pressure fluctuations of diesel fuel in the system. The first two have been extensively studied, but the research on the third one is rather limited. In this article, the synchronous acquisition, data processing system of cavitation

The impact process of fuel drops on a solid dry surface under engine relevant conditions were studied using a numerical method based on smoothed particle hydrodynamics (SPH). The post-impingement properties (mass, velocity, and location) of the splashed secondary drops were analyzed. A drop/wall interaction model was developed on the basis of the SPH simulations. Numerical results show that the mass

The present experimental study extends the Ohnesorge nomogram of liquid jet breakup regimes to viscoelastic liquids and presents a model for the jet breakup length. The experiments are carried out with water and with aqueous solutions of two different flexible polymers. The experiments rely on the visualization of the jets for identifying the breakup mechanism and for measuring the breakup length.

In recent decades direct numerical simulations of liquid-gas flows with interface capturing/tracking method have made great progress. But to address new configurations that contain highly deformed interfaces, a question arises about the validity of the obtained results. Usually, the only solution is to perform a mesh convergence analysis on a well-defined criteria/quantity, which is really costly.

The objective of this study was to investigate the effects of the geometric parameters of a pressure-swirl duplex nozzle (dual orifice) on the spray characteristics of Jet A-1 fuel. Two pilot nozzles with different shapes and two main nozzles with different shapes were tested. The spray characteristics were analyzed by employing laser diagnostic techniques, namely a phase Doppler particle analyzer

The outcomes of fuel drop impact on a combustion chamber wall will affect the fuel-air mixture distribution and subsequent combustion performance of an internal combustion engine. In this paper, the process offuel drop impact on a solid dry surface was simulated, using a numerical method based on smoothed particle hydrodynamics (SPH). This method was first validated using experimental data on the impact

We consider the momentum effects on drop size and distributions during spray atomization. By adding the liquid and gas momentum analysis to conservation equations for mass and energy, we construct a formulation for determination of the spray drop size, number density, and liquid/gas velocities during spray atomization. In this approach, the aerodynamic drag is approximately parameterized by the drag

Two-dimensional axisymmetric large eddy simulation was conducted to model the sheet formation and primary breakup of gelled kerosene and gelled hydrogen peroxide in a pintle injector. This was done by varying the pintle opening distance. To simulate a hollow conical gelled hydrogen peroxide sheet from the center gap and the sheet breakup by the gelled kerosene from the annular gap, volume of fluid

A turbulent jet breakup model is derived using concepts from probability theory. Velocity fluctuations at the free surface are hypothesized to be the cause of turbulent jet breakup. This idea is formalized by treating the fluctuations as random variables, subject to damping from the free surface. In contrast to previous theories, this theory uses a conditional ensemble average to determine quantities

Electrostatic actuation is used for real-time multiphysics feedback control of two-fluid coaxial atomization. This actuation is added to the modulation of the axial and angular momentum of the turbulent coaxial gas stream, for a total of three actuators to control atomization. We characterize the spray real-time response through optical scattering measurements of radial liquid distribution. We apply

The effect of counter electrode curvature on the onset voltage and spray angle of the electrospray in the cone-jet mode is experimentally investigated. Six counter electrodes, including a conventional flat electrode, and five curved (both concave and convex) electrodes are considered. The curvature of the curved electrodes was in the range of 10−33.3 m-1. The applied voltage, the voltage range of the