Analysis of Pressure Propagation in the Combustion Chamber of Diesel Engine by Means of Water Model

Abstract

It was suggested in the previous paper that the area of the connecting passage in a divided chamber type Diesel engine determines wheither the sharp pressure rise in the auxiliary chamber transmits to the main chamber. No attention, however, was paid to the pressure wave propagation in the chamber that would possibly be of importance. In order to make up this, the water analogue method was applied to simulate such a two-dimensional unsteady problem. Test results show that, with a wide connecting passage, a sharp pressure pulse is formed and spreads in the main chamber, followed by a rapid pressure rise and pressure vibration of relatively low pitch. Such pulse and vibration decline with the decrease of the passage area and with smoothing the pressure rise in the auxiliary chamber. Owing to this pulse, the maximum rate of pressure rise in the main chamber is exceedingly larger than the theoretical one predicted in the previous paper, while the average rate coincides virtually with it, if fine waves are ignored.