Photographic Studies of Diesel Combustion in a Quiescent Combustion Chamber

An 8.5 inch bore two stroke engine has been modified into a photographic test rig in which pictures of the complete combustion chamber could be taken vertically upwards through a perspex crowned piston, using a high speed camera.

Tests were carried out using several nozzles of the same total hole area. Two fuelling rates and three different air supply pressures were used. At each test condition thirteen cycles of fired data were recorded on 16 mm high speed colour film. At the same time synchronised transient cylinder pressure and fuel injection data were recorded using an on-line data acquisition system.

Correlation of jet development from photographs with heat release deduced from the cylinder pressure diagrams using a standard single zone technique show differences due to changes in the hole configuration and in air supply pressure, with approximately constant fuel injection rates.