Predesign of an Internal Combustion Engine Intake Manifold by Numerical Solution of Induction Flow

A method is proposed to calculate the characteristics of compressible flow in intake manifold of an internal combustion engine, which can be used as an iterative process to determine the main dimensions of the manifold, such as pipes length and diameter, at the primary stages of internal combustion engine design. To calculate the flow field in the pipes, a computer code has been developed to solve the quasi 1-D Euler’s gas dynamics equations using flux-splitting method. Boundary conditions, such as valves, are modeled using experimental data along with some semi-empirical equations. To verify the accuracy of the method, a four cylinder SI engine manifold, with different intake manifold pipe lengths is simulated by the developed computer code and the overall performance characteristics of the engine such as power, torque and volumetric efficiency are obtained and compared with experiments.