Abstract
When air flows unsteadily in an internal combustion engine through its inlet pipe, chambers and valves, some effects such as friction and inertial forces have direct influence on the volumetric efficiency of the system. The work in this paper aims to investigate numerically and experimentally the pulsating phenomena present in an intake pipe of an internal combustion engine and to discuss the intake jet flow predictions through the novel implementation of a low Mach number preconditioned density-based method, including the three-dimensional modelling of the inlet valve, the inlet pipe and the pulsating effects. The inlet valve movement promotes moderate values of Mach numbers during its opening phase. After the inlet valve closes, the flow is abruptly restricted and a series of pressure waves propagate through the fluid at low Mach numbers. Although the low Mach number preconditioned density-based method is very attractive in this case, the study of the pulsating flow in the internal combustion engine intake systems has not been performed using this method, probably owing to robustness issues and simulation effort. The pressure-based methodology is widely used and, generally, the inlet pipe and pulsating effects are not included in the three-dimensional fluid dynamics simulation. In order to verify the accuracy of the numerical solution, the results are compared with experimental data collected from a bench constructed specifically for this purpose. The numerical results were satisfactory for the amplitudes and the resonance frequencies in the air intake system. Also, different aspects of the jet flow inside the cylinder are shown and discussed.
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