scholarly journals String flash-boiling in gasoline direct injection simulations with transient needle motion

2016 ◽  
Vol 87 ◽  
pp. 90-101 ◽  
Author(s):  
E.T. Baldwin ◽  
R.O. Grover ◽  
S.E. Parrish ◽  
D.J. Duke ◽  
K.E. Matusik ◽  
...  
Keyword(s):  
Direct Injection ◽  
Gasoline Direct Injection ◽  
Flash Boiling

Modeling of Internal and Near-Nozzle Flow for a Gasoline Direct Injection Fuel Injector

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Kaushik Saha ◽  
Sibendu Som ◽  
Michele Battistoni ◽  
Yanheng Li ◽  
Shaoping Quan ◽  
...  
Keyword(s):  
Liquid Fuel ◽  
Numerical Study ◽  
Direct Injection ◽  
Computational Cost ◽  
Volume Averaging ◽  
Operating Conditions ◽  
Gasoline Direct Injection ◽  
Superheated Liquid ◽  
Fuel Injector ◽  
Flash Boiling

A numerical study of two-phase flow inside the nozzle holes and the issuing spray jets for a multihole direct injection gasoline injector has been presented in this work. The injector geometry is representative of the Spray G nozzle, an eight-hole counterbore injector, from the engine combustion network (ECN). Simulations have been carried out for a fixed needle lift. The effects of turbulence, compressibility, and noncondensable gases have been considered in this work. Standard k–ε turbulence model has been used to model the turbulence. Homogeneous relaxation model (HRM) coupled with volume of fluid (VOF) approach has been utilized to capture the phase-change phenomena inside and outside the injector nozzle. Three different boundary conditions for the outlet domain have been imposed to examine nonflashing and evaporative, nonflashing and nonevaporative, and flashing conditions. Noticeable hole-to-hole variations have been observed in terms of mass flow rates for all the holes under all the operating conditions considered in this study. Inside the nozzle holes mild cavitationlike and in the near-nozzle region flash-boiling phenomena have been predicted when liquid fuel is subjected to superheated ambiance. Under favorable conditions, considerable flashing has been observed in the near-nozzle regions. An enormous volume is occupied by the gasoline vapor, formed by the flash boiling of superheated liquid fuel. Large outlet domain connecting the exits of the holes and the pressure outlet boundary appeared to be necessary leading to substantial computational cost. Volume-averaging instead of mass-averaging is observed to be more effective, especially for finer mesh resolutions.

Prediction of spray collapse in multi-hole gasoline direct-injection fuel injectors

2018 ◽  
Vol 20 (1) ◽  
pp. 18-33 ◽  
Author(s):  
Sampath K Rachakonda ◽  
Arman Paydarfar ◽  
David P Schmidt
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Ambient Pressure ◽  
Direct Injection ◽  
Gasoline Direct Injection ◽  
Nozzle Geometry ◽  
Fuel Injectors ◽  
Computational Fluid Dynamics Simulations ◽  
Flash Boiling ◽  
Dynamics Simulations

A parametric study was conducted to predict the conditions leading to spray collapse in multi-hole gasoline direct-injection fuel injectors using computational fluid dynamics simulations. The computational fluid dynamics simulations were performed using an in-house multi-dimensional code that accounts for thermal non-equilibrium and entrainment of the non-condensable gas and coupled with primary atomization. The simulations were performed for a fixed injection pressure and fuel temperature on nine different six-hole injectors. The parameters were varied to include the effects of the ratio of the ambient pressure to the saturation pressure (Pa/Ps), the drill angle, and the diameters of the nozzle and the counter bore, respectively, on the spray. The findings indicate that spray collapse results from a combination of the nozzle geometry, the thermodynamic conditions of the fuel, and the ambient pressure. Spray collapse was observed in injectors with a narrow arrangement of the nozzle holes under extreme flash-boiling conditions with very low ambient pressures and in the case of non-flash-boiling conditions with very high ambient pressures.

The application of a multicomponent droplet vaporization model to gasoline direct injection engines

2003 ◽  
Vol 4 (3) ◽  
pp. 193-218 ◽  
Author(s):  
Y Ra ◽  
R. D. Reitz
Keyword(s):  
Heat Flux ◽  
Present Model ◽  
Direct Injection ◽  
Internal Heat ◽  
Droplet Surface ◽  
Gasoline Direct Injection ◽  
Gas Mixture ◽  
Ambient Temperatures ◽  
Droplet Vaporization ◽  
Flash Boiling

A model for unsteady droplet vaporization is presented that considers the droplet temperature range from flash-boiling conditions to normal evaporation. The theory of continuous thermodynamics was used to model the properties and compositions of multicomponent fuels such as gasoline. In order to model the change of evaporation rate from normal to boiling conditions more realistically, an unsteady internal heat flux model and a new model for the determination of the droplet surface temperature are proposed. An explicit form of the equation to determine the heat flux from the surrounding gas mixture to the droplet/gas interface was obtained from an approximate solution of the quasi-steady energy equation for the surrounding gas mixture, with the interdiffusion of fuel vapour and the surrounding gas taken into account. The model was applied to calculate normal and boiling evaporation processes of droplets for various ambient temperatures and droplet temperatures. Single-droplet evaporation calculated using the present model was compared with the results calculated by using the standard evaporation routine of the KIVA-3V code. Also, simulations of the vaporization of a single-component fuel (iso-octane) were compared with multi-component fuel cases. The vaporization of a hollow cone spray of fuel injected into a cylindrical chamber was simulated for both normal and flash-boiling conditions using the KIVA-3V code implemented with the present model. In addition, the model was applied to a realistic gasoline direct injection engine.

scholarly journals Numerical Analysis of GDI Flash Boiling Sprays Using Different Fuels

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5925
Author(s):  
Raul Payri ◽  
Pedro Marti-Aldaravi ◽  
Rami Abboud ◽  
Abian Bautista
Keyword(s):  
Alternative Fuels ◽  
Fuel Injection ◽  
Ambient Pressure ◽  
Direct Injection ◽  
Saturation Pressure ◽  
Combustion Process ◽  
Gasoline Direct Injection ◽  
Injection Process ◽  
Engine Combustion ◽  
Flash Boiling

Modeling the fuel injection process in modern gasoline direct injection engines plays a principal role in characterizing the in–cylinder mixture formation and subsequent combustion process. Flash boiling, which usually occurs when the fuel is injected into an ambient pressure below the saturation pressure of the liquid, is characterized by fast breakup and evaporation rates but could lead to undesired behaviors such as spray collapse, which significantly effects the mixture preparation. Four mono–component fuels have been used in this study with the aim of achieving various flashing behaviors utilizing the Spray G injector from the Engine Combustion Network (ECN). The numerical framework was based on a Lagrangian approach and was first validated for the baseline G1 condition. The model was compared with experimental vapor and liquid penetrations, axial gas velocity, droplet sizes and spray morphology and was then extended to the flash boiling condition for iso–octane, n–heptane, n–hexane, and n–pentane. A good agreement was achieved for most of the fuels in terms of spray development and shape, although the computed spray morphology of pentane was not able to capture the spray collapse. Overall, the adopted methodology is promising and can be used for engine combustion modeling with conventional and alternative fuels.

Investigations on near-field atomization of flash boiling sprays for gasoline direct injection related applications

Fuel ◽  
2019 ◽  
Vol 257 ◽  
pp. 116097 ◽  
Author(s):  
Xuesong Li ◽  
Shangze Yang ◽  
Tianyun Li ◽  
David L.S. Hung ◽  
Min Xu
Keyword(s):  
Near Field ◽  
Direct Injection ◽  
Gasoline Direct Injection ◽  
Flash Boiling

Characteristics of flash boiling and its effects on spray behavior in gasoline direct injection injectors: A review

Fuel ◽  
2020 ◽  
Vol 271 ◽  
pp. 117600 ◽  
Author(s):  
Mengzhao Chang ◽  
Ziyoung Lee ◽  
Sungwook Park ◽  
Suhan Park
Keyword(s):  
Direct Injection ◽  
Gasoline Direct Injection ◽  
Flash Boiling
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