Investigation of fuel sprays in the near field of diesel and gasoline injection nozzles

Definition of the Spray Near Field

The Analysis of fuel sprays in the near field of the injection nozzle is challenging for diesel as well as gasoline injections due to the high optical density for current measurement techniques. The near field reaches up to a distance of approx. 20 mm to the nozzle orifice.

For an investigation of the spray characteristics (velocity, droplet size distribution), highly specialised optical measurement techniques are required which are able to detect on one hand the high velocities of the spray (~ 600 m/s) and on the other hand small scale structures and droplets (~ 10 μm).

For a better metrological accessibility of this measurement area, several measurement techniques have been newly developed or adapted at the institute.

Optical Measurement Techniques

• Optical Connectivity Method: Analysis of the intact core of the fuel spray.

• Structural Image Velocimetry: Analysis of the velocity distribution of the fuel spray in the near nozzle area starting from 2 mm distance to the nozzle.

• Laser-2-Focus Velocimeter: Analysis of the droplet velocities and sizes starting from 5 mm distance to the nozzle. Measurements are carried out in cooperation with the Nagasaki University. Setup at the ITV is planned.

• X-Ray Diagnostics: Analysis of the structure, mass distribution and velocity of the spray starting from the nozzle orifice. Measurements are carried out in cooperation with the Argonne National Laboratory in Chicago.