In the study of matching an exhaust turbocharger to a diesel engine, it is very important to know how the pulsating flows change through a pipe junction. This paper aims to improve the accuracy of a flow calculation using the method of characteristics. In usual, for the boundary condition at a junction, hypothesis of whether constant pressure or constant pressure-loss-coefficient is adopted. It is well known, however, that pressure loss coefficient of a junction changes much with flow rate. We propose a new procedure for connecting a pulsating upstream flow with a downstream flow in which the pressure loss is taken into account dynamically. As an unsteady pressure-loss-coefficient, we used one measured in steady state quasi-steadily. By comparing calculation results with experimental results, it becomes clear that this procedure improves calculation accuracy remarkably, especially in the prediction of flow late.
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