The Relationship between Rate of Pressure Rise and Connecting Passage Area in a Swirl Chamber Type Diesel Engine

Abstract

This paper is a sequel to the investigation on effects of the connecting passage area of a divided chamber type Diesel engine on the knock intensity : The maximum rates of pressure rise in the auxiliary-and the main chambers of a swirl chamber type engine were measured from indicator cards under a light load. The test results are summarized as follows : Above 1000 rpm of the engine speed, the rate of pressure rise in the swirl chamber and the amplitude of detonation-like pressure oscillation rapidly augment as the area ratio is reduced. The relationship between rates of pressure rise in the main chamber and in the swirl chamber can be classified into three stages according to the area ratio. In the smallest ratio range the gas flowing out from the swirl chamber is delayed by the connecting passage, thus resulting in a relatively low rate of pressure rise in the main chamber compared with that in the swirl chamber. In the intermediate area range the rate of pressure rise in the main chamber is nearly equal to that in the swirl chamber. The larger area ratio gives the higher rate of pressure rise in the main chamber than that in the swirl chamber because of the burning of fuel escaping in the main chamber.