Determination of thermodynamic gas parameters in branched pipes in internal combustion engines

The paper presents theoretical and experimental results of calculation of basic gas parameters in the branched pipes. These parameters are required in one-dimensional computer models for prediction of non-steady gas flow in complicated multi-cylinder engine ducts. The gas flow near the junction is described with assumption of compressed and unsteady flow. Mathematical equations describing the gas flow are given in the paper on basis of mass, energy balance in the junction, pressure drop between pipes and conservation of energy in the section of supplied pipe. Equation systems enable to solve values of pressure, gas velocity, sound speed, density and concentration of gas components in every pipe connected to the joint. The different cases of the flow area are considered. The obtained parameters at the junction outflow are needed as initial values for calculation of unsteady gas flow in the outflow pipes. Verification of the method was conducted experimentally and pressure loss coefficients are given in the paper. Additionally by using Fluent program with high mesh density of the T-pipe junction the thermodynamic parameters (pressure, velocity, temperature) are compared with those obtained from 0D model. The model enables calculation the thermodynamic parameters of inflow and outflow systems in multi-cylinder IC engines in computer program.