Frequency based approach for simulating pressure waves at the inlet of internal combustion engines using a parameterized model

Today’s downsized turbocharged engines mainly focus on improving low end torque and increasing mass flow rate, this is done in order to improve the overall thermodynamic efficiency of the engine and to gain a lower BSFC. An integral part of any combustion engine is the air intake line that has a first order effect on engine filling and emptying. The wave action that takes place is usually simulated using one-dimensional codes. This paper presents a novel technique based on a frequency domain characterization of the intake line. A link over a wide frequency spectrum is identified between the instantaneous mass flow at the valve and the dynamic pressure response. This model is implemented into Simulink via a transfer function and coupled to GT-Power to produce an engine simulation. A shock tube experimental campaign was conducted for a number of tubes with varying lengths and diameters. The parameters of this transfer function are measured for each case then combined with gas dynamic theory and a frequency analysis to identify a law of behavior as a function of pipe geometry. The final model is validated on a single cylinder engine in GT-Power for a variety of pipe geometry.

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