Simulation of Exhaust Gas Residuals in a Turbocharged, Spark Ignition Engine

Highly downsized, Direct Injection (DI) engines benefit strongly from cylinder scavenging where possible, to reduce internal residuals thereby reducing the occurrence of knock. Some researchers also suggest that non-homogeneous distribution of internal residuals at high load could contribute to pre-ignition or ‘mega-knock’ with much higher pressure amplitude than that of common knock. For this reason, a computational study was conducted to assess the residual gas fraction and in-cylinder distribution, using the combustion geometry of the three cylinder, 1.2L MAHLE Downsizing engine, which has proven to be a very robust and reliable research tool into the effects of combustion effects under a number of different operating conditions. This study used a CFD model of the cylinder gas exchange. ES-ICE coupled with STAR-CD was employed for a moving mesh, transient in-cylinder simulation. The boundary conditions were provided by a correlated 1-D (GT-power) model, with several scenarios simulated including engine speed, valve overlap and port geometry. The residual distributions at part load with different inlet ports were also assessed.

[1]  U. Spicher,et al.  Knock Behavior of SI-Engines: Thermodynamic Analysis of Knock Onset Locations and Knock Intensities , 2006 .

[2]  Fabian Mauss,et al.  Effect of Inhomogeneities in the End Gas Temperature Field on the Autoignition in SI Engines , 2000 .

[3]  Koji Yoshida,et al.  An Experimental Study Concerning the influence of Hot Residual Gas On Combustion , 2000 .

[4]  Andrew Smallbone,et al.  The Influence of Simulated Residual and NO Concentrations on Knock Onset for PRFs and Gasolines , 2004 .

[5]  Darius Mehta,et al.  The Effect of EGR on Low-Speed Pre-Ignition in Boosted SI Engines , 2011 .

[6]  Steven Wooldridge,et al.  Measurement and Analysis of the Residual Gas Fraction in an SI Engine with Variable Cam Timing , 2004 .

[7]  Franz X. Tanner,et al.  Relating Integral Length Scale to Turbulent Time Scale and Comparing k-ε and RNG k-ε Turbulence Models in Diesel Combustion Simulation , 2002 .

[8]  Ronald K. Hanson,et al.  Simultaneous Measurement of In-Cylinder Temperature and Residual Gas Concentration in the Vicinity of the Spark Plug by Wavelength Modulation Infrared Absorption , 2007 .

[9]  Ricardo Martinez-Botas,et al.  Boost system selection for a heavily downsized spark ignition prototype engine , 2012 .

[10]  Simon Schmuck-Soldan,et al.  Fundamental Approach to Investigate Pre-Ignition in Boosted SI Engines , 2011 .

[11]  Darius Mehta,et al.  Engine Operating Condition and Gasoline Fuel Composition Effects on Low-Speed Pre-Ignition in High-Performance Spark Ignited Gasoline Engines , 2011 .

[12]  G. Konig,et al.  End gas autoignition and knock in a spark ignition engine , 1990 .

[13]  Fabian Mauss,et al.  The Influence of Nitric Oxide on the Occurrence of Autoignition in the End Gas of Spark Ignition Engines , 2002 .

[14]  Hans-Erik Ångström,et al.  The Influence of Residual Gases on Knock in Turbocharged SI-Engines , 2000 .