Research Papers: Flows in Complex Systems

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

[+] Author and Article Information
B. Yadollahi

PhD Graduate
e-mail: Byadollahi@aut.ac.ir

M. Boroomand

Associate Professor
e-mail: Boromand@aut.ac.ir
Amirkabir University of Technology (Tehran polytechnic),
Tehran, Iran 15875-4413

1Corresponding author. Present address: Department of Aerospace Engineering, Amirkabir University of Technology (Tehran Polytechnic), 424 Hafez Avenue, Tehran, Iran, 15875-4413.

Contributed by the Fluids Engineering Division of ASME for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received April 29, 2012; final manuscript received May 12, 2013; published online June 10, 2013. Assoc. Editor: Pavlos P. Vlachos.

J. Fluids Eng 135(9), 091101 (Jun 10, 2013) (9 pages) Paper No: FE-12-1219; doi: 10.1115/1.4024560 History: Received April 29, 2012; Revised May 12, 2013

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.

Copyright © 2013 by ASME
Your Session has timed out. Please sign back in to continue.



Grahic Jump Location
Fig. 1

A view of mesh in the near field of the injector exit

Grahic Jump Location
Fig. 2

The results of jet penetration for grid independency check

Grahic Jump Location
Fig. 3

Left the inlet mass flow rate for the first validation case [1], and right: the comparison of jet tip penetration

Grahic Jump Location
Fig. 4

Comparison of jet penetration and flow field for second validation case

Grahic Jump Location
Fig. 5

A view of base engine geometry and ports

Grahic Jump Location
Fig. 6

Effect of combustion chamber geometry on jet shape at a planar section through injector axis, all cases at 40 °CA BTDC, RAFR = 2.33

Grahic Jump Location
Fig. 7

Temporal variations of mixture characteristics for different combustion chamber geometries

Grahic Jump Location
Fig. 8

Equivalence ratio contours on a planar section through cylinder axis for large bowl geometry at different crank angles

Grahic Jump Location
Fig. 9

A comparison of results for λ = 1.5 and λ = 2.0; left: flammable and rich mass fractions, and right: flammable and rich fuel mass fractions

Grahic Jump Location
Fig. 10

The proposed spark plug locations on a contour plot of equivalence ratio at ignition timing

Grahic Jump Location
Fig. 11

Temperature contour on a planar section through cylinder axis for different spark plug locations, all cases at 10° BTDC

Grahic Jump Location
Fig. 12

The in-cylinder results for spark location study; left: pressure trace, and right: temperature

Grahic Jump Location
Fig. 13

Combustion results for ignition timing study; left: pressure trace, and right: heat release rate

Grahic Jump Location
Fig. 14

The peak pressure crank angle and value for ignition timing study




Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In