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In gasoline direct injection engines with stratified-combustion strategies only a short time is available for mixture preparation. Therefore, investigations are carried out to evaluate the influence of high injection pressure up to 50 MPa in order to optimize the mixture preparation. Two types of multi-hole injectors are analyzed in a pressure vessel under various pressure and temperature conditions. Laser light sheet visualization technique is applied in order to determine spray characteristics like shape, angle, penetration depth and spray width. To determine the velocity of the air surrounding the spray, a PIV (Particle Image Velocimetry) measurement technique is used. Droplet sizes and velocities are measured with a Phase Doppler Anemometer (PDA) in different positions in the spray center and at the spray edge. Spray visualization experiments show the influence of evaporation on spray propagation at higher temperatures.

The main objectives of this investigation are the visualisation of the flame propagation depending on different boundary conditions. Turbulence intensities, wall-temperatures and an air-fuel ratios were varied in a wide range. For the experiments a rapid compression machine with a quadratic piston and a good optical access is used which allows to observe the entire burning. With an additionally integrated turbulence generator it is possible to create a defined turbulence field in the burning chamber.