The Effect of Piston Head Geometry on Natural Gas Direct Injection and Mixture Formation in a SI Engine with Centrally Mounted Single-Hole Injector

2011 ◽  
Author(s):  
Bijan Yadollahi ◽  
Masoud Boroomand
Keyword(s):  
Natural Gas ◽  
Direct Injection ◽  
Si Engine ◽  
Mixture Formation ◽  
Single Hole ◽  
Piston Head

A Numerical Investigation of Combustion and Mixture Formation in a Compressed Natural Gas DISI Engine With Centrally Mounted Single-Hole Injector

2013 ◽  
Vol 135 (9) ◽  
Author(s):  
B. Yadollahi ◽  
M. Boroomand
Keyword(s):  
Natural Gas ◽  
Internal Combustion Engines ◽  
Gasoline Engine ◽  
Direct Injection ◽  
Combustion Process ◽  
Spark Ignition ◽  
Computational Effort ◽  
Single Hole ◽  
Piston Head ◽  
Spark Plug

Direct injection of natural gas into the cylinder of spark ignition (SI) engines has shown a great potential to achieve the best fuel economy and reduced emission levels. Since the technology is rather new, in-cylinder flow phenomena have not been completely investigated. In this study, a numerical model has been developed in AVL FIRE software to perform an investigation of natural gas direct injection into the cylinder of spark ignition internal combustion engines. In this regard, two main parts have been taken into consideration aiming to convert a multipoint port fuel injection (MPFI) gasoline engine to a direct injection natural gas (NG) engine. In the first part of the study, multidimensional simulations of transient injection process, mixing, and flow field have been performed. Using the moving mesh capability, the validated model has been applied to methane injection into the cylinder of a direct injection engine. Five different piston head shapes have been taken into consideration in the investigations. An inwardly opening single-hole injector has been adapted to all cases. The injector location has been set to be centrally mounted. The effects of combustion chamber geometry have been studied on the mixing of air-fuel inside the cylinder via the quantitative and qualitative representation of results. In the second part, an investigation of the combustion process has been performed on the selected geometry. The spark plug location and ignition timing have been studied as two of the most important variables. Simulation of transient injection was found to be a challenging task because of required computational effort and numerical instabilities. Injection results showed that the narrow bowl piston head geometry is the most suited geometry for NG direct injection (DI) application. A near center position has been shown to be the best spark plug location based on the combustion studies. It has been shown that advanced ignitions timings of up to 50 degrees crank angle ( °CA) should be used in order to obtain better combustion performance.

Combined effect of injection timing and injection angle on mixture formation and combustion process in a direct injection (DI) natural gas rotary engine

Energy ◽  
2017 ◽  
Vol 128 ◽  
pp. 519-530 ◽  
Author(s):  
Baowei Fan ◽  
Jianfeng Pan ◽  
Wenming Yang ◽  
Zhenhua Pan ◽  
Stephen Bani ◽  
...  
Keyword(s):  
Natural Gas ◽  
Direct Injection ◽  
Combustion Process ◽  
Combined Effect ◽  
Injection Timing ◽  
Mixture Formation ◽  
Injection Angle ◽  
Rotary Engine

Multidimensional Modeling of Natural Gas Jet and Mixture Formation in DI SI Engines: Development and Validation of a Virtual Injector Model

2009 ◽  
Author(s):  
Mirko Baratta ◽  
Andrea E. Catania ◽  
Francesco C. Pesce
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Combustion Engine ◽  
Direct Injection ◽  
Test Chamber ◽  
Computational Cost ◽  
Computational Domain ◽  
Rarefaction Waves ◽  
Mixture Formation ◽  
Ic Engine

During the last years, the integration of computational CFD tools in the internal combustion (IC) engine design process has continuously been increased, allowing to save time and cost as the need of experimental prototypes has diminished. Numerical analyses of IC engine flows are rather complex from both the conceptual and operational sides. In fact, such flows involve a variety of unsteady phenomena, and the right balance between numerical solution accuracy and computational cost should be always reached. The present paper is focused on computational modeling of natural gas (NG) direct injection (DI) processes from a poppet-valve injector into a bowl-shaped combustion chamber. At high injection pressures, the efflux of gas from the injector and the mixture formation processes include compressible and turbulent flow features, such as rarefaction waves and shock formation, which are difficult to be accurately captured by the numerical simulation, particularly when combustion chamber geometry is complex and piston and intake/exhaust valve grids are moving. A three-dimensional moving grid model of the combustion engine chamber, originally developed by the authors, was enhanced by increasing the accuracy in the sonic section proximity of the critical valve seat nozzle, in order to precisely capture the expansion dynamics the methane undergoes inside the injector and immediately downstream from it. The enhanced numerical model was validated by comparing numerical results to Schlieren experimental images for nitrogen injection into a constant-volume bomb. Then, numerical studies were carried out in order to characterize the fuel jet properties and the evolution of mixture-formation for a centrally-mounted injector configuration in both cases of a pancake test chamber and the real-shaped engine chamber. Finally, the fluid properties computed by the model in the throat-section of the critical nozzle were taken as reference data for developing a new effective ‘virtual injector’ model, which allows the designer to remove the whole computational domain upstream from the sonic section of the nozzle, keeping the flow properties practically unchanged. The outcomes of such a virtual injector model were shown to be in very good agreement with the results of the enhanced complete injector model, confirming the reliability of the proposed novel approach.

Multi-Dimensional Modeling of Direct Natural-Gas Injection and Mixture Formation in a Stratified-Charge SI Engine with Centrally Mounted Injector

2008 ◽  
Vol 1 (1) ◽  
pp. 607-626 ◽  
Author(s):  
Mirko Baratta ◽  
Andrea E. Catania ◽  
Ezio Spessa ◽  
Lothar Herrmann ◽  
Klaus Roessler
Keyword(s):  
Natural Gas ◽  
Gas Injection ◽  
Si Engine ◽  
Mixture Formation ◽  
Stratified Charge ◽  
Dimensional Modeling

An Investigation of Mixture Formation Processes During Start-Up of a Natural Gas Powered SI Engine

1998 ◽  
Author(s):  
Joseph M. Brault ◽  
Deborah Sneckenberger Maymir ◽  
Mohammad Samimy ◽  
Masato Matsuki
Keyword(s):  
Natural Gas ◽  
Formation Processes ◽  
Si Engine ◽  
Mixture Formation ◽  
Start Up

Multidimensional Modeling of Natural Gas Jet and Mixture Formation in Direct Injection Spark Ignition Engines—Development and Validation of a Virtual Injector Model

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Mirko Baratta ◽  
Andrea E. Catania ◽  
Francesco C. Pesce
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Combustion Engine ◽  
Direct Injection ◽  
Test Chamber ◽  
Computational Cost ◽  
Computational Domain ◽  
Rarefaction Waves ◽  
Mixture Formation ◽  
Ic Engine

During the last few years, the integration of CFD tools in the internal combustion (IC) engine design process has continually increased, allowing time and cost savings as the need for experimental prototypes has diminished. Numerical analyses of IC engine flows are rather complex from both the conceptual and operational sides. In fact, these flows involve a variety of unsteady phenomena and the right balance between numerical solution accuracy and computational cost should always be reached. The present paper is focused on computational modeling of natural gas (NG) direct injection (DI) processes from a poppet-valve injector into a bowl-shaped combustion chamber. At high injection pressures, the gas efflux from the injector and the mixture formation processes include turbulent and compressible flow features, such as rarefaction waves and shock formation, which are difficult to accurately capture with numerical simulations, particularly when the combustion chamber geometry is complex and the piston and intake/exhaust valve grids are moving. In this paper, a three-dimensional moving grid model of the combustion engine chamber, originally developed by the authors to include simulation of the actual needle lift, has been enhanced by increasing the accuracy in the proximity of the sonic section of the critical valve-seat nozzle, in order to precisely capture the expansion dynamics the methane undergoes inside the injector and immediately downstream from it. The enhanced numerical model was then validated by comparing the numerical results to Schlieren experimental images for gas injection into a constant-volume bomb. Numerical studies were carried out in order to characterize the fuel-jet properties and the evolution of mixture formation for a centrally mounted injector configuration in the case of a pancake-shaped test chamber and the real engine chamber. Finally, the fluid properties calculated by the model in the throat section of the critical nozzle were taken as reference data for developing a new effective virtual injector model, which allows the designer to remove the whole computational domain upstream from the sonic section of the nozzle, keeping the flow properties virtually unchanged there. The virtual injector model outcomes were shown to be in very good agreement with the results of the enhanced complete injector model, substantiating the reliability of the proposed novel approach.

Characteristics of Mixture Formation in a Direct Injection SI Engine with Optimized In-Cylinder Swirl Air Motion

1999 ◽  
Author(s):  
Akihiko Kakuhou ◽  
Tomonori Urushihara ◽  
Teruyuki Itoh ◽  
Yasuo Takagi
Keyword(s):  
Direct Injection ◽  
Si Engine ◽  
Mixture Formation ◽  
Air Motion
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