NUMERICAL INVESTIGATION OF NATURAL GAS DIRECT INJECTION PROPERTIES AND MIXTURE FORMATION IN A SI ENGINE

Abstract

In this study, a numerical model has been developed in AVL FIRE software to perform investigation of Direct Natural Gas Injection into the cylinder of Spark Ignition Internal Combustion Engines. In this regard two main parts have been taken into consideration, aiming to convert an MPFI gasoline engine to direct injection NG engine. In the first part of study multi-dimensional numerical simulation of transient injection process, mixing and flow field have been performed via three different validation cases in order to assure the numerical model validity of results. Adaption of such a modeling was found to be a challenging task because of required computational effort and numerical instabilities. In all cases present results were found to have excellent agreement with experimental and numerical results from literature. In the second part, 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 along with two injector types have been taken into consideration in investigations. A centrally mounted injector location has been adapted to all cases. The effects of injection parameters, combustion chamber geometry, injector type and engine RPM have been studied on mixing of air-fuel inside cylinder. Based on the results, suitable geometrical configuration for a NG DI Engine has been discussed.

Keywords

Dates

  • Submission Date2012-06-05
  • Revision Date2012-09-20
  • Acceptance Date2012-11-06

DOI Reference

10.2298/TSCI120605222Y

References

  1. Chiodi, M., Berner, H. J., Bargende, M., Investigation on different Injection Strategies in a Direct- Injected Turbocharged CNG-Engine, SAE paper 2006-01-3000, 2006.
  2. Li, Y., et al., Characteristic and Computational Fluid Dynamics Modeling of High-Pressure Gas Jet Injection, ASME Transactions, Journal of Engineering for Gas Turbines and Power, 126(2004), pp. 192-197.
  3. Huang, Z., et al., Visualization study of natural gas direct injection combustion, Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 217(2003), pp.667-673.
  4. Huang, Z., et al., Basic characteristics of direct injection combustion fuelled with compressed natural gas and gasoline using a rapid compression machine, Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 217(2003), pp.1031-1038.
  5. Huang, Z., et al., Correlation of ignitability with injection timing for direct injection combustion fuelled with compressed natural gas and gasoline, Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 217(2003), pp. 499-506.
  6. Zeng, K., et al., Combustion characteristics of a direct-injection natural gas engine under various fuel injection timings, Journal of Applied Thermal Engineering, 26(2006), pp. 806-813.
  7. Papageorgakis, G., Assanis, D. N., Optimizing Gaseous Fuel-Air Mixing in Direct Injection Engines using an RNG Based k-e Model, SAE Transactions, Journal of Engines, 107(1999), pp. 82-107.
  8. Han, Z., Reitz, R. D., Turbulence Modeling of Internal Combustion Engines Using RNG k-e Models, Combustion Science & Technology, 106(1995), pp. 267-295.
  9. Li, G., et al., Optimization Study of Pilot-Ignited Natural Gas Direct-Injection in Diesel Engines, SAE Paper No.1999-01-3556, 1999.
  10. Abraham, J., Magi, V., Computation of Transient Jets: RNG k-e Model Versus Standard k-e Model, SAE Paper No. 970885, 1997.
  11. Ouellette, P., Hill, P. G., Turbulent Transient Gas Injections, ASME Transactions, Journal of Fluids Engineering, 122(2000), pp. 743-753.
  12. Abraham, J., What is Adequate Resolution in the Numerical Computations of Transient Jets?, SAE Paper No. 970051, 1997.
  13. Mather, D. K., Reitz, R. D., Modeling the Effects of Auxiliary Gas Injection on Diesel Engine Combustion and Emissions, SAE Transactions, Journal of Engines, 109(2002), pp. 443-458.
  14. Baratta, M., Catania, E., Pesce, F. C., Multidimensional modeling of natural gas jet and mixture formation in DI SI engines- Development and validation of a virtual Nozzle model, ASME proceedings of the Internal Combustion Engines Division technical conference ICES 2009, (2009), pp. 583-596.
  15. Baratta, M., Catania, A. E., Pesce, F. C., Multidimensional Modeling of Natural Gas jet and Mixture Formation in Direct Injection Spark Ignition Engines- Development and Validation of a Virtual Injector Model, ASME Transactions, Journal of Fluids Engineering, 133(2011), pp. 041304-1 - 041304-14.
  16. Andreassi, L., et al., Multidimensional modeling of gaseous injection: Analysis of an impinging jet, International Journal of Heat and Fluid Flow, 31(2010), 5, pp. 909-915.
  17. Baratta, M., et al., Multi-dimensional modeling of Direct Natural-Gas Injection and Mixture Formation in a Stratified-Charge SI Engine with Centrally Mounted Injector, SAE paper 2008-01- 0975, 2008.
  18. Kim, G. H., Kirkpatrick, A., Mitchell, C., Computational Modeling of Natural Gas Injection in a large Bore Engine, ASME Transactions, Journal of Engineering for Gas Turbines and Power, 126(2004), pp. 656-664.
  19. Yadollahi, B., Boroomand, M., The Effect of Piston Head Geometry on Natural Gas Direct Injection and Mixture Formation in a SI Engine with Centrally Mounted Single-Hole Injector, SAE paper 2011-01-2448, 2011.
  20. Yadollahi, B., Boroomand, M., A Numerical Investigation of Combustion chamber Geometry Effects on Natural Gas Direct Injection Properties in a SI Engine with Centrally Mounted Multi- Hole Injector, ASME proceedings of the Internal Combustion Engines Division technical conference ICES2012, 2012.
  21. Tomita, E., et al., Visualization of ambient air motion and entrainment into a transient gas jet impinging on a flat wall, SAE paper 952513, 1995.
Volume 18, Issue 1, Pages39 -52