Comparison of numerical and system dynamics methods for modeling wave propagation in the intake manifold of a single-cylinder engine

The automotive industry is striving to adopt model-based engine design and optimization procedures to reduce development time and costs. In this scenario, first-principles gas dynamic models predicting the mass, energy and momentum transport in the engine air path system with high accuracy and low computation effort are extremely important today for performance prediction, optimization and cylinder charge estimation and control. This paper presents a comparative study of two different modeling approaches to predict the one-dimensional unsteady compressible flow in the engine air path system. The first approach is based on a quasi-3D finite volume method, which relies on a geometrical reconstruction of the calculation domain using networks of zero-dimensional elements. The second approach is based on a model-order reduction procedure that projects the nonlinear hyperbolic partial differential equations describing the 1D unsteady flow in engine manifolds onto a predefined basis. The two models are compared against experimental data obtained from a single cylinder engine for motorcycle applications. The results presented allow one to establish a trade-off between accuracy, stability and computation time for each solution method, in light of potential applications to engine performance simulation.