Ethanol (E100) can be utilised in spark ignition engines for passenger car vehicles. This brings ... more Ethanol (E100) can be utilised in spark ignition engines for passenger car vehicles. This brings a challenge to the durability of the fuel injection system components since its use can result in corrosion, further enhanced by cavitation-induced erosion. This work reports computational fluid dynamics (CFD) predictions for both the flow development and the locations prone to cavitation erosion in multi-hole gasoline direct injection (GDi) injectors operated with E100. The compressible form of the Navier-Stokes equations is solved numerically considering the motion of the injector's needle valve. Thermodynamic and mechanical equilibrium is assumed between the liquid, vapour and non-condensable gas; E100 liquid and vapour are considered as a barotropic fluids where the corresponding variation in density with pressure and the speed of sound are estimated via a relevant equation of state; an
L'invention concerne un injecteur, notamment pour l'injection multipoints de carburant da... more L'invention concerne un injecteur, notamment pour l'injection multipoints de carburant dans un moteur a combustion interne. Un tel injecteur est generalement monte dans la culasse d'un tel moteur pour injecter directement le carburant dans la chambre de combustion d'un cylindre d'un tel moteur. L'invention vise a optimiser la buse (120) d'un tel injecteur de sorte a accroitre l'energie cinetique transversale du jet en provoquant un ecoulement tourbillonnaire du fluide injecte lors de son passage dans la buse. Ce resultat est obtenu avec un injecteur, comprenant une cavite d'injection (210) sensiblement cylindrique d'axe longitudinal (101), la buse d'injection comprenant une pluralite d'orifices epaules (220, 220') sensiblement cylindriques, debouchant de maniere excentree par rapport a l'axe longitudinal (101) dans la cavite (210), de sorte a provoquer un ecoulement tourbillonnaire dans chaque orifice du fluide injecte.
This paper is to present a detailed case study on how the nozzle flow dynamics influences the pri... more This paper is to present a detailed case study on how the nozzle flow dynamics influences the primary breakup inthe spray formation process of diesel injection. The investigation was based on a 3-hole real-application nozzle with highly tapered injection holes using a URANS-LES (Large Eddy Simulation) hybrid approach in combination with the coupled Volume of Fluid (VOF) and Level Set method. High resolution LES was applied to simultaneously resolve the multi-scale nozzle flow dynamics downstream of the needle seat and the primary breakup process in the near-nozzle spray. Phase Contrast X-ray imaging (PCX) was applied to characterize the liquid-gas interfaces in the near-nozzle spray for validation purposes. The results provide detailed information on how the vortex shedding and vortex interactions in the injection hole drives the jet deformation, ligament anddroplet formation in the primary breakup process. DOI: http://dx.doi.org/10.4995/ILASS2017.2017.5707
Die Dynamik der Düsenströmung und die Zerstäubungsprozesse sind von zentraler Bedeutung für die D... more Die Dynamik der Düsenströmung und die Zerstäubungsprozesse sind von zentraler Bedeutung für die Düsenoptimierung der Hochdruck-Benzindirekteinspritzung (GDI) und der daraus resultierenden motorischen Gemischbildung und Verbrennung. Experimentelle Techniken sind wegen der kleinen Skalen, hohen Geschwindigkeiten und des optisch schwer zugänglichen Interessensbereichs nur eingeschränkt einsetzbar. Fortschritte in hochgenauen, hochauflösenden Large-Eddy-Simulationen, insbesondere in Kombination mit einer weiterentwickelten Level-Set-Volume-of-Fluid-Technik für das Fluid-Gas-Interface-Tracking, können diese experimentelle Lücke füllen. Dieser Beitrag zeigt, wie modernste Methoden der numerischen Strömungsdynamik zum grundlegenden Verständnis physikalischer Prozesse beitragen und wie Delphi Tech nologies diese Erkenntnisse umsetzt.
Understanding nozzle flow dynamics and the spray formation process is of key importance for gasol... more Understanding nozzle flow dynamics and the spray formation process is of key importance for gasoline direct injection nozzle design optimization and engine emission control. Experimental techniques are limited in their ability to probe these processes because of the small scales, high speeds, and optically opaque area of interest. Advances in high-fidelity, high-resolution Large Eddy Simulation, enhanced with the Coupled Level Set Volume of Fluid technique for interface tracking, can fill this experimental gap. This paper presents an example of how this new computational fluid dynamics functionality can be used to understand some of the fundamental physical processes involved in high pressure gasoline direct injection, and how it is helping Delphi Techno logies to develop their next generation of fuel injectors.
What fluid dynamic instabilities in the nozzle flow trigger ligament and droplet formation during... more What fluid dynamic instabilities in the nozzle flow trigger ligament and droplet formation during the primary breakup of a diesel jet?
Erfindungsgemas wird eine Filtervorrichtung zum Filtern eines Kraftstoffes mit einem vorbestimmte... more Erfindungsgemas wird eine Filtervorrichtung zum Filtern eines Kraftstoffes mit einem vorbestimmten Kraftstoffdruck vorgeschlagen, die aufweist: einen Filterkopf, welcher eine um eine Langsachse der Filtervorrichtung angeordnete Offnung zur Zufuhrung des Kraftstoffes aufweist; einen Filtermittenbereich, welcher einen im Wesentlichen zylindrischen Querschnitt aufweist und eine Vielzahl von Lochern zur Filterung von Partikeln aus dem zugefuhrten Kraftstoff hat; und einen Filterboden, welcher eine um die Langsachse der Filtervorrichtung angeordnete Einstulpung, die eine Stromung des zugefuhrten Kraftstoffes in den Filtermittenbereich oder in den Filterkopf reflektiert, und einen um die Einstulpung ausgebildeten Ringkanalbereich, welcher die Partikel aus der Stromung des zugefuhrten Kraftstoffes und die mittels der Locher gefilterten Partikel mittels Zentrifugalkraft und/oder Schwerkraft sammelt, aufweist.
In the present study, free convection and heat transfer behavior of electrically conducting fluid... more In the present study, free convection and heat transfer behavior of electrically conducting fluid in the boundary layer over a vertical continuously stretching surface is investigated. The effects of free convection, magnetic field, suction/blowing at the surface and the stretching speed of the surface on the flow and heat transfer characteristics are considered. By applying one-parametric group theory to analysis of the problem, a similarity solution is found. The governing equations of continuity, momentum and energy are solved numerically by a fourth-order Runge-Kutta scheme. The numerical results, which are obtained for the flow and heat transfer characteristics, reveal the influences of the parameters.
This work deals with the spray behaviour of a PDI injector for gasoline fuel, which is driven by ... more This work deals with the spray behaviour of a PDI injector for gasoline fuel, which is driven by a piezoelectric element and equipped with a outward opening A-shape hollow cone valve. Spray characterization experiments were carried out in a conditioned pressure chamber by using Mie scattering technique and PDA measurement. First, the experiment was performed for non-evaporating spray by keeping the chamber temperature at 20 °C and fuel temperature at -10 °C. Spray contour, droplet size and velocity were obtained for various rail and chamber pressure values. Then the Mie scattering technique was applied to characterize evaporating sprays under equivalent engine operation conditions. Fuel variation was performed for n-hexane, isooctane, n-decane, fuel mixtures consisting of n-hexane, isooctane and n-decane, ethanol, gasoline and E85. The data obtained were used for the validation of the simulation results. The CFD simulation was based on the Lagrange approach using the commercial code...
Investigation to the mixed convective heat and mass transfer over a horizontal plate has been car... more Investigation to the mixed convective heat and mass transfer over a horizontal plate has been carried out. By applying transformation group theory to analysis of the governing equations of continuity, momentum, energy and diffusion, we show the existence of similarity solution for the problem provided that the temperature and concentration at the wall are proportional to x 4/(7-5n) and that the moving speed of the plate is proportional to x (3-n)/(7-5n), and further obtain a similarity representation of the problem. The similarity equations have been solved numerically by a fourth-order Runge–Kutta scheme. The numerical results obtained for Pr=0.72 and various values of the parameters Sc, K 1, K 2 and K 3 reveals the influence of the parameters on the flow, heat and mass transfer behavior.
This paper investigates the complex multiphase flow developing inside the micro-orifices of diese... more This paper investigates the complex multiphase flow developing inside the micro-orifices of diesel injector nozzles during pilot injection. High speed micro-visualisations of a transparent serial production nozzle tip replica are used to record the multiphase flow inside the flow orifices as well as nearnozzle spray development. The physical processes taking place are explained with the aid of a three-phase homogeneous mixture model utilized in the context of Large Eddy Simulations. Phase-change due to cavitation is modelled with a Rayleigh-Plesset equation based model, while compressibility of all the phases is considered. Numerical simulations shed light on the interaction between the vortex flow, liquid inertia and cavitation formation that take place simultaneously with air entrainment from the surrounding environment into the injector's sac volume during the injection and the dwell
This paper reports a numerical study of the effect of fuel property and fuel temperature change o... more This paper reports a numerical study of the effect of fuel property and fuel temperature change on mechanical cavitating flow in generic nozzle geometries. The work was based on the commercial CFD code ANSYS CFX11.0. The liquid and the vapor phase were treated as a ...
ABSTRACT In the present study, free convection and heat transfer behavior of electrically conduct... more ABSTRACT In the present study, free convection and heat transfer behavior of electrically conducting fluid in the boundary layer over a vertical continuously stretching surface is investigated. The effects of free convection, magnetic field, suction/blowing at the surface and the stretching speed of the surface on the flow and heat transfer characteristics are considered. By applying one-parametric group theory to analysis of the problem, a similarity solution is found. The governing equations of continuity, momentum and energy are solved numerically by a fourth-order Runge-Kutta scheme. The numerical results, which are obtained for the flow and heat transfer characteristics, reveal the influences of the parameters.
The turbulent fluid and particle interaction in the turbulent boundary layer for cross flow over ... more The turbulent fluid and particle interaction in the turbulent boundary layer for cross flow over a tube was studied experimentally. A phase Doppler anemometer (PDA) was used to measure the mean and fluctuation velocities of both phases. Two size ranges of particles (30-60 pm and N-150 pm) at certain concentrations were used to investigate the effect of the particle size on the mean velocity profiles and turbulent intensity levels. The measurements clearly demonstrated that the larger particles damped the fluid turbulence. For the smaller particles, this damping effect was less noticeable. The measurement further showed a delay in the separation point for two-phase turbulent cross flow over a tube. 0 1997 Elsevier Science S.A.
ABSTRACT Previous experimental work shows that velocity ratio is the principal independent variab... more ABSTRACT Previous experimental work shows that velocity ratio is the principal independent variable to determine the flow behavior of coaxial jets. This study focusing on the effect of velocity ratio on the flow characteristics such as the velocity and kinetic energy profiles, centerline velocity decaying, flow growing and entraining of the jet, presents a detailed numerical simulation of a coaxial jet with a secondary parallel moving stream. It is found that radial profiles of the mean velocity component u depending on the velocity ratio show good similarity in the fully developed zone. Compared with available experimental data, the results show that the use of standard κ-ε model leads to good agreement between the numerical results and experimental data.
Ethanol (E100) can be utilised in spark ignition engines for passenger car vehicles. This brings ... more Ethanol (E100) can be utilised in spark ignition engines for passenger car vehicles. This brings a challenge to the durability of the fuel injection system components since its use can result in corrosion, further enhanced by cavitation-induced erosion. This work reports computational fluid dynamics (CFD) predictions for both the flow development and the locations prone to cavitation erosion in multi-hole gasoline direct injection (GDi) injectors operated with E100. The compressible form of the Navier-Stokes equations is solved numerically considering the motion of the injector's needle valve. Thermodynamic and mechanical equilibrium is assumed between the liquid, vapour and non-condensable gas; E100 liquid and vapour are considered as a barotropic fluids where the corresponding variation in density with pressure and the speed of sound are estimated via a relevant equation of state; an
L'invention concerne un injecteur, notamment pour l'injection multipoints de carburant da... more L'invention concerne un injecteur, notamment pour l'injection multipoints de carburant dans un moteur a combustion interne. Un tel injecteur est generalement monte dans la culasse d'un tel moteur pour injecter directement le carburant dans la chambre de combustion d'un cylindre d'un tel moteur. L'invention vise a optimiser la buse (120) d'un tel injecteur de sorte a accroitre l'energie cinetique transversale du jet en provoquant un ecoulement tourbillonnaire du fluide injecte lors de son passage dans la buse. Ce resultat est obtenu avec un injecteur, comprenant une cavite d'injection (210) sensiblement cylindrique d'axe longitudinal (101), la buse d'injection comprenant une pluralite d'orifices epaules (220, 220') sensiblement cylindriques, debouchant de maniere excentree par rapport a l'axe longitudinal (101) dans la cavite (210), de sorte a provoquer un ecoulement tourbillonnaire dans chaque orifice du fluide injecte.
This paper is to present a detailed case study on how the nozzle flow dynamics influences the pri... more This paper is to present a detailed case study on how the nozzle flow dynamics influences the primary breakup inthe spray formation process of diesel injection. The investigation was based on a 3-hole real-application nozzle with highly tapered injection holes using a URANS-LES (Large Eddy Simulation) hybrid approach in combination with the coupled Volume of Fluid (VOF) and Level Set method. High resolution LES was applied to simultaneously resolve the multi-scale nozzle flow dynamics downstream of the needle seat and the primary breakup process in the near-nozzle spray. Phase Contrast X-ray imaging (PCX) was applied to characterize the liquid-gas interfaces in the near-nozzle spray for validation purposes. The results provide detailed information on how the vortex shedding and vortex interactions in the injection hole drives the jet deformation, ligament anddroplet formation in the primary breakup process. DOI: http://dx.doi.org/10.4995/ILASS2017.2017.5707
Die Dynamik der Düsenströmung und die Zerstäubungsprozesse sind von zentraler Bedeutung für die D... more Die Dynamik der Düsenströmung und die Zerstäubungsprozesse sind von zentraler Bedeutung für die Düsenoptimierung der Hochdruck-Benzindirekteinspritzung (GDI) und der daraus resultierenden motorischen Gemischbildung und Verbrennung. Experimentelle Techniken sind wegen der kleinen Skalen, hohen Geschwindigkeiten und des optisch schwer zugänglichen Interessensbereichs nur eingeschränkt einsetzbar. Fortschritte in hochgenauen, hochauflösenden Large-Eddy-Simulationen, insbesondere in Kombination mit einer weiterentwickelten Level-Set-Volume-of-Fluid-Technik für das Fluid-Gas-Interface-Tracking, können diese experimentelle Lücke füllen. Dieser Beitrag zeigt, wie modernste Methoden der numerischen Strömungsdynamik zum grundlegenden Verständnis physikalischer Prozesse beitragen und wie Delphi Tech nologies diese Erkenntnisse umsetzt.
Understanding nozzle flow dynamics and the spray formation process is of key importance for gasol... more Understanding nozzle flow dynamics and the spray formation process is of key importance for gasoline direct injection nozzle design optimization and engine emission control. Experimental techniques are limited in their ability to probe these processes because of the small scales, high speeds, and optically opaque area of interest. Advances in high-fidelity, high-resolution Large Eddy Simulation, enhanced with the Coupled Level Set Volume of Fluid technique for interface tracking, can fill this experimental gap. This paper presents an example of how this new computational fluid dynamics functionality can be used to understand some of the fundamental physical processes involved in high pressure gasoline direct injection, and how it is helping Delphi Techno logies to develop their next generation of fuel injectors.
What fluid dynamic instabilities in the nozzle flow trigger ligament and droplet formation during... more What fluid dynamic instabilities in the nozzle flow trigger ligament and droplet formation during the primary breakup of a diesel jet?
Erfindungsgemas wird eine Filtervorrichtung zum Filtern eines Kraftstoffes mit einem vorbestimmte... more Erfindungsgemas wird eine Filtervorrichtung zum Filtern eines Kraftstoffes mit einem vorbestimmten Kraftstoffdruck vorgeschlagen, die aufweist: einen Filterkopf, welcher eine um eine Langsachse der Filtervorrichtung angeordnete Offnung zur Zufuhrung des Kraftstoffes aufweist; einen Filtermittenbereich, welcher einen im Wesentlichen zylindrischen Querschnitt aufweist und eine Vielzahl von Lochern zur Filterung von Partikeln aus dem zugefuhrten Kraftstoff hat; und einen Filterboden, welcher eine um die Langsachse der Filtervorrichtung angeordnete Einstulpung, die eine Stromung des zugefuhrten Kraftstoffes in den Filtermittenbereich oder in den Filterkopf reflektiert, und einen um die Einstulpung ausgebildeten Ringkanalbereich, welcher die Partikel aus der Stromung des zugefuhrten Kraftstoffes und die mittels der Locher gefilterten Partikel mittels Zentrifugalkraft und/oder Schwerkraft sammelt, aufweist.
In the present study, free convection and heat transfer behavior of electrically conducting fluid... more In the present study, free convection and heat transfer behavior of electrically conducting fluid in the boundary layer over a vertical continuously stretching surface is investigated. The effects of free convection, magnetic field, suction/blowing at the surface and the stretching speed of the surface on the flow and heat transfer characteristics are considered. By applying one-parametric group theory to analysis of the problem, a similarity solution is found. The governing equations of continuity, momentum and energy are solved numerically by a fourth-order Runge-Kutta scheme. The numerical results, which are obtained for the flow and heat transfer characteristics, reveal the influences of the parameters.
This work deals with the spray behaviour of a PDI injector for gasoline fuel, which is driven by ... more This work deals with the spray behaviour of a PDI injector for gasoline fuel, which is driven by a piezoelectric element and equipped with a outward opening A-shape hollow cone valve. Spray characterization experiments were carried out in a conditioned pressure chamber by using Mie scattering technique and PDA measurement. First, the experiment was performed for non-evaporating spray by keeping the chamber temperature at 20 °C and fuel temperature at -10 °C. Spray contour, droplet size and velocity were obtained for various rail and chamber pressure values. Then the Mie scattering technique was applied to characterize evaporating sprays under equivalent engine operation conditions. Fuel variation was performed for n-hexane, isooctane, n-decane, fuel mixtures consisting of n-hexane, isooctane and n-decane, ethanol, gasoline and E85. The data obtained were used for the validation of the simulation results. The CFD simulation was based on the Lagrange approach using the commercial code...
Investigation to the mixed convective heat and mass transfer over a horizontal plate has been car... more Investigation to the mixed convective heat and mass transfer over a horizontal plate has been carried out. By applying transformation group theory to analysis of the governing equations of continuity, momentum, energy and diffusion, we show the existence of similarity solution for the problem provided that the temperature and concentration at the wall are proportional to x 4/(7-5n) and that the moving speed of the plate is proportional to x (3-n)/(7-5n), and further obtain a similarity representation of the problem. The similarity equations have been solved numerically by a fourth-order Runge–Kutta scheme. The numerical results obtained for Pr=0.72 and various values of the parameters Sc, K 1, K 2 and K 3 reveals the influence of the parameters on the flow, heat and mass transfer behavior.
This paper investigates the complex multiphase flow developing inside the micro-orifices of diese... more This paper investigates the complex multiphase flow developing inside the micro-orifices of diesel injector nozzles during pilot injection. High speed micro-visualisations of a transparent serial production nozzle tip replica are used to record the multiphase flow inside the flow orifices as well as nearnozzle spray development. The physical processes taking place are explained with the aid of a three-phase homogeneous mixture model utilized in the context of Large Eddy Simulations. Phase-change due to cavitation is modelled with a Rayleigh-Plesset equation based model, while compressibility of all the phases is considered. Numerical simulations shed light on the interaction between the vortex flow, liquid inertia and cavitation formation that take place simultaneously with air entrainment from the surrounding environment into the injector's sac volume during the injection and the dwell
This paper reports a numerical study of the effect of fuel property and fuel temperature change o... more This paper reports a numerical study of the effect of fuel property and fuel temperature change on mechanical cavitating flow in generic nozzle geometries. The work was based on the commercial CFD code ANSYS CFX11.0. The liquid and the vapor phase were treated as a ...
ABSTRACT In the present study, free convection and heat transfer behavior of electrically conduct... more ABSTRACT In the present study, free convection and heat transfer behavior of electrically conducting fluid in the boundary layer over a vertical continuously stretching surface is investigated. The effects of free convection, magnetic field, suction/blowing at the surface and the stretching speed of the surface on the flow and heat transfer characteristics are considered. By applying one-parametric group theory to analysis of the problem, a similarity solution is found. The governing equations of continuity, momentum and energy are solved numerically by a fourth-order Runge-Kutta scheme. The numerical results, which are obtained for the flow and heat transfer characteristics, reveal the influences of the parameters.
The turbulent fluid and particle interaction in the turbulent boundary layer for cross flow over ... more The turbulent fluid and particle interaction in the turbulent boundary layer for cross flow over a tube was studied experimentally. A phase Doppler anemometer (PDA) was used to measure the mean and fluctuation velocities of both phases. Two size ranges of particles (30-60 pm and N-150 pm) at certain concentrations were used to investigate the effect of the particle size on the mean velocity profiles and turbulent intensity levels. The measurements clearly demonstrated that the larger particles damped the fluid turbulence. For the smaller particles, this damping effect was less noticeable. The measurement further showed a delay in the separation point for two-phase turbulent cross flow over a tube. 0 1997 Elsevier Science S.A.
ABSTRACT Previous experimental work shows that velocity ratio is the principal independent variab... more ABSTRACT Previous experimental work shows that velocity ratio is the principal independent variable to determine the flow behavior of coaxial jets. This study focusing on the effect of velocity ratio on the flow characteristics such as the velocity and kinetic energy profiles, centerline velocity decaying, flow growing and entraining of the jet, presents a detailed numerical simulation of a coaxial jet with a secondary parallel moving stream. It is found that radial profiles of the mean velocity component u depending on the velocity ratio show good similarity in the fully developed zone. Compared with available experimental data, the results show that the use of standard κ-ε model leads to good agreement between the numerical results and experimental data.
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