Spatially Resolved Determination of Fuel/Air Ratio Inside a Direct Injection SI-Engine Under Real Fuel Conditions 2003-01-2007

The present work describes a new method which allows the spatially resolved quantitative determination of gaseous hydrocarbon densities in droplet laden flows. The technique is especially dedicated to a quantitative and linearly spatially resolved measurement of air/fuel ratio (λ-value) in direct injection Otto engines under stratified operation and by use of regular gasoline (Euro Super). The new method is based on spontaneous Raman scattering. It is applied to the investigation of the air/fuel ratio distribution inside an in the close surroundings of the spray cone of different DI-fuel injectors under stratified and homogeneous engine operation conditions. Both crank angle resolved snap shot and cyclical averaged measurements are presented. Simultaneously the planar gasoline distribution is detected by LIF of aromatic hydrocarbons which are native constituents of regular gasoline. It is shown, that the linear spatially resolved air/fuel distributions measured by means of LIF correlates well with the Raman data.