Technical Paper
Micro-Diesel Combustion of Entrained Air in High Pressure Fuel Injection Systems
2018-05-21
2018-01-5019
Modern high pressure diesel fuel injection equipment (FIE) is designed to operate with high quality fuel that is free of external contaminants. Undissolved bubbles of air that are normally managed by the low pressure fuel delivery circuit, may be present for a variety of reasons. Any bubbles that persist will violently implode following entry to the high pressure system. The effects of bubble collapse under conditions close to atmospheric pressure are well documented as cavitation collapse. The objective of the present paper is to study the implosion of air/vapor bubbles in diesel fuel when exposed to much higher pressures under controlled conditions resembling those in modern FIE. The results demonstrate that the adiabatic temperature rise is sufficient to initiate combustion, causing visible light emission, damage to nearby materials and formation of black carbonaceous precipitates in the fuel. Similar black precipitates have been previously reported in the field.