HIGH PRECISION AND TIME SAVING METHOD FOR MODELING THE INLET MANIFOLD OF AN INTERNAL COMBUSTION ENGINE

摘要

The pressure wave propagation in the inlet system of the IC Engine, produced by the piston and valves motion, has a significant effect on the cylinder filling. The main objective of the study is to model the compressible and unsteady flow in intake manifolds. This is achieved by using a new approach that gives precise results with smaller computational time compared to the classical one-dimensional approach. Using a multi-frequency approach, the inlet system was studied. A transfer function was defined to link the air mass flow rate and the pressure response at the inlet valve. The function was identified using a flow bench working in unsteady conditions. The main purpose of the 0D model is to replace the native 1D inlet geometry of the IC Engine in the simulation code. In other words, a coupling was made using the 1D simulation code GT-Power, where the inlet system of the ICE was replaced by its transfer function. A typical driving cycle is run with a GT power model including transfer function to prove that it is possible to reduce the simulation time with high accuracy level compared to a classical native GT power model using only inlet geometry. The final model was validated in 2 steps, first on a single cylinder and then on a four cylinder naturally aspirated engine. The model validation was conducted using precision criterion on volumetric efficiency and on instantaneous pressure upstream of the intake valve. Results between GT-Power native 1D model, transfer function model and Engine Tests were compared. Good agreement was obtained between the engine tests and the new 0D model. This new approach is an alternative method for modeling the intake geometry of an IC engine, taking into account the pressure wave phenomena.