Quantitative Determination of Fuel Air Mixture Distributions in an Internal Combustion Engine using PLIF of Acetone

Publisher Website
Google Scholar
Abstract
Quantitative determination of planar fuel/air mixture distribution in an internal SI engine are obtained using planar laser induced fluorescence of acetone. In order to get quantitative information different fuel tracer substances have been investigated. Special requirements have to be fulfilled by the tracer molecule with regard to the application under the unstationary and hostile conditions of internal combustion. The most important is that the fluorescence intensity has to be directly proportional to the fuel density. It must be unaffected by surrounding gas composition, temperature‐ and pressure‐fluctuations. As it turned out during the experiments acetone meets this unusual requirements almost perfectly.The experiments were carried out in one cylinder of a modified production line four cylinder SI engine from Volkswagen AG. Time resolved planar fuel distributions were obtained for the whole mixture formation process during the intake, the compression and at the beginning of the combustion stroke. Single shot and cyclic averaged measurements revealed a) cycle‐to‐cycle variations as well as recurring structures of the fuel distribution, b) mixture uniformity and c) flow field structures. The direct relationship between the acetone fluorescence intensity and the fuel density allows the quantitative determination of 2‐D fuel/air ratio maps for a multitude of different crankangles.