Use of 1D-3D Coupled Simulation to Develop an Intake Manifold System 2010-01-1534
During the development of a air intake manifold simulation is necessary to verify the component characteristics in terms of flow considering runner in-balance as focus. Results can also present exhaust gases recirculation (EGR) distribution affecting each of the different runners in order to verify if those recirculated exhaust gases were been equally distributed among all the runner outlets or, at least, presenting a percentual difference of EGR concentration in each runner inside a defined tolerance range. Aiming these results some calculation techniques were used as follow:
1D modeling as well as 3D modeling was used
1D model was built using GT-Power and 3D modeling was done using computational fluid dynamics based on ANSYS FLUENT.
First results were obtained from 1D model and 3D model running apart. 1D modeling was focused in performance issues (torque and power); 3D modeling was a steady state, multiphase calculation, looking for qualitative results like density and mixing of gases, to verify the flow distribution inside the intake manifold. Pressure loss results were verified but not as main result of this work.
A baseline EGR mixer was also tested looking for its efficiency and a new EGR mixer design proposal could took place at this moment, if it was necessary. The distribution of EGR for the runners was obtained from a 1D-3D coupling, it means:
1D model and 3D model were run simultaneously,
1D flow results at manifold inlet and EGR valve outlet were passed to CFD model and used as boundary conditions and
3D flow results at runners were so passed to 1D model and used as boundary conditions to continue the flow calculation.
That sequence was run until convergence were obtained considering at least 10 coupled cycles.