Analysis and modeling of the fluid-dynamic effects in branched exhaust junctions of ICE

The influence of exhaust junction geometry on flow-dynamics of exhaust gas is analyzed. The authors propose an experimental characterization method based on the measurement of the instantaneous pressure in the junction operating with engine exhaust flow and solving the problems posed for the accurate instantaneous pressure measurements under the adverse temperature condition. In this paper the method is applied to tww "Y" type junctions with a reed being the unique difference between them, to determine the influence of this element on the junction behavior. The analysis of the experimental results denotes two major differences: the characteristics of the wave reflected at the junction, and the energy of the pulse transmitted to the lateral branch of the junction. The results of the analysis are introduced in the junction modeling used in a one-dimensional gas dynamic model with an important improvement in the agreement of the modeled predictions with the experimental measurements.