抄録
The unsteady flow through the exhaust junctions of a diesel engine has been investigated, with the object of finding the boundary conditions in the computer program for the matching of the engine to an exhaust turbocharger. In a previous paper, the interesting feature was observed that the joining flow loss coefficients established from the time mean values of measured pressures and velocities near the junction had extreme values at a certain ratio of flow rate. But the reason for this tendency was unclear. In the present paper, the effects of pulse frequency, amplitude ratio and phase difference between the main and branch pulsating flows on the loss coefficients have been studied experimentally, and quasi-steady flow analysis has supported the existence of the extreme value of the loss coefficients. It has been concluded that the usefulness of quasi-steady approaches to boundary conditions is limited to certain ratios of amplitude and frequency.
