A Study on Ignition and Combustion of a Diesel Spray by Means of a Rapid Compression Machine

Abstract

A free-piston type rapid compression machine has been developed to simulate combustion process occurring in a diesel engine. A light piston is pneumatically shot and gets hammered in a stop ring at the compression end. A satisfactory performance has been achieved by this device, permitting a near-constant elevated pressure and temperature sufficient to explore ignition of a fuel spray and the subsequent combustion. From a series of tests carried out on this machine, it has been shown that the ignition lag exhibits little or small dependence on pressure and temperature at some elevated pressures and temperatures. It has been also pointed out that in the so-called diffusive burning period, combustion proceeds with self-accelerating rate of heat release in the case when much fuel is allotted to this period, while the rate declines monotonically with time in the contrary case.