Simulation of gasoline engines

 

 

Phenomenological combustion rate model

  • Entrainment approach with hemispherical flame propagation, in the calculation of which the laminar flame speed and the specific turbulence in the combustion chamber are taken into account
  • Can be used for both liquid and gaseous fuels
  • Combination of turbulence and combustion models permits precise representation of the combustion rate, depending on the state of the cylinder charge at "intake-closes"

 

Quasi-dimensional charge motion and turbulence model

  • The stationary tumble figures from the intake ducts are used to calculate the tumble generated during the intake (described as Taylor-Green vortex).
  • Incorporation of the turbulence generated directly at the valve seat.
  • In the combustion chamber, the turbulence is calculated based on production and dissipation terms.

FKFS knock model

  • Takes into account the influence of turbulence on the temperature in the uncombusted end gas.
  • Sub-model for hotspots on the wall.
  • Internal ignition point control permits robust and very rapid adjustment of the center of gravity position for optimum efficiency at each operating point, taking into account the knocking tendencies of the engine being investigated.
  • For transient calculations, the ignition point controller can illustrate the effect of a real antiknock controller (springs back for knocking combustion cycles).

 

Cycle fluctuation model

  • Variation of ignition period and flame propagation in the combustion rate model.
  • Combustion model reacts appropriately to the general boundary conditions of the operating point being investigated.
  • Evaluation of the effects on integral operating parameters (IMEP, BSFC, pmax, …). In this way, it is possible to predict fuel consumption while taking cycle fluctuation into account.
  • Differences in the results between the results of the average combustion cycle and the average of all combustion cycle variations are represented and can be used as a signal for a throttle controller.
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