Due to the longer auto-ignition time with liquid fuels compared with hydrogen, the understanding of interaction of shock wave with the spray and subsequent vapor mixing are significant to design ramjet/scramjet with liquid fuel spray. In this study, an Eulerian-Lagrangian framework with detailed transport models for the Eulerian gas-phase species properties and Lagrangian spray, atomization, evaporation

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, 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

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;

Polyoxymethylenether (OME) is a promising fuel in CO2 reduction for a prospective change in the transportation sector. To see the effect of different fuel properties, the mixture formation of OME3, OME4 and European standard Diesel fuel are investigated for a passenger car and two different commercial vehicle injectors with different nozzle hole diameter at engine relevant conditions of 5 MPa ambient

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 a heat flux by an infinite slab. Our previous models made use of a basic assumption that the evaporation commences simultaneously for all droplets at a given pre-specified evaporation temperature, irrespective of the size of the droplets

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 gas flow, depends on the droplet generation mechanism at the beginning of the mixing process. High-velocity gas flows affect droplets and can atomize

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 fluids 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 paper describes an experiment in which the fuel was cooled and the

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 implementation of high-pressure oxy-fired systems (HiPrOx) 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

The current work demonstrates experimental and computational study of diesel spray under non-evaporating and evaporating conditions considering effects of hole diameter and rail pressure. Three single hole injectors with hole diameters of 0.101mm, 0.122mm and 0.133mm are experimented with 120MPa injection pressure while 0.122mm hole diameter injector is further tested with 100MPa and 140MPa injection

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

Drop impact are seen in various applications, e.g. 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, i.e. either for a moving surface, or an inclined surface. Therefore, we conducted a comparative study between drop impact onto

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

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

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

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

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

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