Effect of Ambient Pressure on the Behavior of Single-Component Fuels in a Gasoline Multi-Hole Injector

Abstract The injection characteristics of neat ethanol and pure iso-octane are studied under different ambient pressure and temperature conditions. Injection under flash-boiling conditions can enhance liquid atomization and evaporation, providing the possibility of improvement in the fuel/air mixing. These super-heated conditions often introduce phenomena that are not taken into account in the standard modeling of sprays for engine applications. The present work proposes a numerical investigation of the behavior of Engine Combustion Network’s 8-hole spray-G injector, starting at the subcooled nominal condition and reducing the ambient pressure at constant low temperature to reach the flare flash-boiling condition. To initialize the properties of the injected fuel, the flow in the nozzle is simulated with a Eulerian approach, handling the two phases with a mixture model and the phase change, due to cavitation and flash boiling, with the Homogenous Relaxation Model. A map of the mixture’s kinematic and thermal behavior is obtained at the interface between the injector and the chamber to initialize the Lagrangian simulations. A literature-based vaporization model is implemented to obtain the proper description of the characteristic features of a multi-hole spray under super-heated conditions, like plume-plume interaction. The numerical representation of the spray is validated in terms of penetration and radial spreading on DBI images, reproducing the light attenuation profiles caused by the presence of the liquid spray. Simulations show that coupled nozzle flow and spray calculations capture the spray morphology and shape better compared to calculations performed without considering the nozzle flow simulation details, especially under flare flash conditions.

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Comparison and Application of Dynamic Mesh Techniques in Nozzle-Flow Simulation

10.4271/2017-01-0849 ◽

2017 ◽

Author(s):

Chao Gong ◽

Roland Baar

Keyword(s):

Flow Simulation ◽

Dynamic Mesh ◽

Nozzle Flow

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Flashboiling atomization in nozzles for GDI engines

Proceedings ILASS–Europe 2017. 28th Conference on Liquid Atomization and Spray Systems ◽

10.4995/ilass2017.2017.4750 ◽

2017 ◽

Cited By ~ 2

Author(s):

Sebastian Bornschlegel ◽

Chris Conrad ◽

Lisa Eichhorn ◽

Michael Wensing

Keyword(s):

Penetration Depth ◽

High Speed ◽

Aerodynamic Drag ◽

Ambient Pressure ◽

Rapid Expansion ◽

Gasoline Direct Injection ◽

Coolant Temperature ◽

Concentrated Mass ◽

Flash Boiling ◽

Gdi Engines

Flashboiling denotes the phenomenon of rapid evaporation and atomization at nozzles, which occurs when fluidsare injected into ambient pressure below their own vapor pressure. It happens in gasoline direct injection (GDI) engines at low loads, when the cylinder pressure is low during injection due to the closed throttle valve. The fuel temperature at the same time approaches cylinder head coolant temperature due to the longer dwell time of the fuel inside the injector. Flash boiling is mainly beneficial for atomization quality, since it produces small droplet sizes and relative broad and homogenous droplet distributions within the spray. Coherently, the penetration depth normally decreases due to the increased aerodynamic drag. Therefore the thermal properties of injectors are often designed to reach flash boiling conditions as early as possible. At the same time, flash boiling significantly increases the risk of undesired spray collapsing. In this case, neighbouring jets converge and form a single jet. Due to the now concentrated mass, penetration depth is enhanced again and can lead to liner or piston wetting in addition to the overall diminished mixture formation.In order to understand the underlying physics, it is important to study the occurring phenomena flashboiling and jet-to-jet interacting i.e. spray collapsing separately. To this end, single hole injectors are built up to allow for an isolated investigation of flashboiling. The rapid expansion at the nozzle outlet is visualized with a microscopic high speed setup and the forces that lead to the characteristic spray expansion are discussed. Moreover, the results on the macroscopic spray in terms of penetration, cone angles and vapor phase are shown with a high speed Schlieren setup. Resulting droplet diameters and velocities are measured using LDA/PDA.As a result, we find a comprehensive picture of flash boiling. The underlying physics can be described and discussed for the specific case of high pressure injection at engine relevant nozzle geometries and conditions, but independently from neighbouring jets. These findings provide the basis to understand and investigate flashboilingand jet-to-jet interaction as distinct, but interacting subjects rather than a combined phenomenon.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4750

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Flash boiling hollow-cone fuel spray from a piezoelectric fuel injector under low ambient pressure

International Journal of Powertrains ◽

10.1504/ijpt.2020.108407 ◽

2020 ◽

Vol 9 (1/2) ◽

pp. 3

Author(s):

Zengyang Wu ◽

Libing Wang ◽

Tiegang Fang

Keyword(s):

Ambient Pressure ◽

Fuel Spray ◽

Fuel Injector ◽

Hollow Cone ◽

Flash Boiling

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Coupled in-nozzle flow and spray simulation of Engine Combustion Network Spray-G injector

International Journal of Engine Research ◽

10.1177/1468087420960612 ◽

2020 ◽

pp. 146808742096061

Author(s):

Balaji Mohan ◽

Jihad Badra ◽

Jaeheon Sim ◽

Hong G Im

Keyword(s):

Cone Angle ◽

Flow Simulation ◽

Published Data ◽

Nozzle Flow ◽

Piv Measurements ◽

Injection Model ◽

Image Velocimetry ◽

Spray Plume ◽

Engine Combustion ◽

Phase Change Phenomena

A coupled Eulerian-Lagrangian approach was employed to Engine Combustion Network (ECN) Spray-G simulations. The Eulerian in-nozzle flow simulation was conducted with a small plenum attached to the nozzles, and the results were fed to the Lagrangian spray simulation. For Eulerian simulation, the homogeneous relaxation model (HRM) coupled with the volume of fluid (VOF) method was used. HRM proved to be good at predicting the phase change phenomena due to vaporization mechanisms, that is, both cavitation and flash boiling. As a one-way coupling, quantities such as rate of injection (ROI), mass injected through each hole, discharge coefficient, spray plume angle and half cone angle predicted from the Eulerian simulations were used as the initial and boundary conditions for the subsequent Lagrangian spray simulations using the blob injection model. Non-flashing (Spray-G1) and flashing (Spray-G2) spray was simulated, and the results were validated quantitatively against the published data in terms of the liquid and vapor penetration lengths, and good agreements were obtained. Furthermore, the simulation predicted the liquid and gas axial velocity and sauter mean diameter for Spray-G1 condition in agreement with the droplet size and particle image velocimetry (PIV) measurements from literature.

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Underexpanded Micro-nozzle Flow Simulation with Coupled Thermal-Fluid Modeling

2007 International Conference on Thermal, Mechanical and Multi-Physics Simulation Experiments in Microelectronics and Micro-Systems. EuroSime 2007 ◽

10.1109/esime.2007.360025 ◽

2007 ◽

Author(s):

Jose Hermida Quesada ◽

Jose A. Morinigo ◽

Francisco Caballero Requena

Keyword(s):

Flow Simulation ◽

Nozzle Flow ◽

Fluid Modeling ◽

Micro Nozzle

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A Review Paper on Simulation and Modeling of Combustion Characteristics under High Ambient and High Injection of Biodiesel Combustion

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.773-774.580 ◽

2015 ◽

Vol 773-774 ◽

pp. 580-584

Author(s):

Adiba Rhaodah Andsaler ◽

Amir Khalid ◽

Him Ramsy ◽

Norrizam Jaat

Keyword(s):

Cfd Simulation ◽

Ambient Pressure ◽

Combustion Characteristics ◽

Spray Angle ◽

Effect Of Temperature ◽

Gas Temperature ◽

Common Rail System ◽

High Injection ◽

Air Mixing ◽

Temperature And Pressure

This paper describes simulation of combustion characteristics under high ambient and high injection of biodiesel combustion by using CFD simulation. Diesel engine performance and emissions is strongly couple with fuel atomization and spray processes, which in turn are strongly influenced by injector flow dynamics. The principal objective of this research is to seek the effect of temperature and pressure on the spray characteristics, as well as fuel-air mixing characteristics. Experiments were performed in a constant volume chamber at specified ambient gas temperature and pressure. This research was continued with injecting diesel fuel into the chamber using a Bosch common rail system. Direct photography technique with a digital camera was used to clarify the real images of spray pattern, liquid length and vapor penetration. The method of the simulation of real phenomenon of diesel combustion with optical access rapid compression machine is also reviewed and experimental results are presented. The liquid phase of the spray reaches a maximum penetration distance soon after the start of injection, while the vapor phase of the spray continues to penetrate downstream. The condition to which the fuel is affected was estimated by combining information on the block temperature, ambient temperature and photographs of the spray. The increases in ambient pressure inside the chamber resulting in gain of spray area and wider spray angle. Thus predominantly promotes for a better fuel-air mixing. All of the experiments will be conducted and run by using CFD. The simulation will show in the form of images.

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Nozzle Flow Simulation by Small Disturbance Approximation and Euler Method

Journal of Physics Conference Series ◽

10.1088/1742-6596/2012/1/012048 ◽

2021 ◽

Vol 2012 (1) ◽

pp. 012048

Author(s):

Fanrui Cheng ◽

Yang Xu ◽

Wenbo Zhou

Keyword(s):

Flow Simulation ◽

Euler Method ◽

Nozzle Flow ◽

Small Disturbance

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Control of Lateral Composition Distribution in Graded Films of Soluble Solid Systems A1−xBx by Partitioned Dual-Beam Pulsed Laser Deposition

Coatings ◽

10.3390/coatings10060540 ◽

2020 ◽

Vol 10 (6) ◽

pp. 540

Author(s):

Joe Sakai ◽

José Manuel Caicedo Roque ◽

Pablo Vales-Castro ◽

Jessica Padilla-Pantoja ◽

Guillaume Sauthier ◽

...

Keyword(s):

Pulsed Laser Deposition ◽

Ambient Pressure ◽

Thickness Distribution ◽

Pulsed Laser ◽

Laser Deposition ◽

Composition Gradient ◽

Composition Distribution ◽

Dual Beam ◽

Soluble Solid ◽

Characteristic Features

Lateral compositionally-graded thin films are powerful media for the observation of phase boundaries as well as for high-throughput materials exploration. We herein propose a method to prepare epitaxial lateral compositionally-graded films using a dual-beam pulsed laser deposition (PLD) method with two targets separated by a partition. Tuning the ambient pressure and the partition—substrate gap makes it possible to control of the gradient length of the deposits at the small sizes (≤ 10 mm) suitable for commercial oxide single crystal substrates. A simple Monte Carlo simulation qualitatively reproduced the characteristic features of the lateral thickness distribution. To demonstrate this method, we prepared (1−x)PbTiO3—xPbZrO3 and (1−x)LaMnO3—xLa0.6Sr0.4MnO3 films with lateral composition gradient widths of 10 and 1 mm, respectively, with the partitioned dual PLD.

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