Search Results

Improved understanding of the active combustion chain “injection - vaporisation - mixture formation - ignition - combustion - exhaust gas emissions” is important for the further development of IC engines with respect to fuel consumption and pollutant emissions. By means of multidimensional optical, mostly laser-based measurement techniques, a modern passenger car common rail system, applied to an optically accessible engine, was investigated. The utilisation of a new optical detection system allowed a simultaneous detection of the liquid phase by Mie scattering, the flame propagation from flame luminosity and the soot formation by laser-induced incandescence inside the combustion bowl of the engine. By such simultaneous measurements, direct dependencies of single combustion phenomena on fuel injection parameters can be resolved, and in particular soot formation and oxidation can be correlated to the actual combustion situation.

Many details of the diesel spray breakup in real technical applications are still quite unknown because of the difficulties in the measurement techniques to obtain data inside the dense spray within the first millimeters downstream the nozzle exit. At the LTT-Erlangen the time-resolved Mie scattering technique in combination with a high resolving long distance-microscope is used to investigate this region. In contrast to previous works published by the LTT, the presented investigations have been carried out using a passenger car common-rail injection system equipped with six different injection nozzles. The aim of the presented investigations is to identify the influence of the nozzles geometry on the primary spray break up. With the taken 2D Mie scattering images many information can be extracted according to this topic, e. g., the development of the microscopic spray angle and local droplet size distributions.

The transport of goods is mainly realised by the use of heavy-duty vehicles equipped with diesel engines as a drive assembly. Considering the high flexibility and reliability as well as the growing interest in saving environmental resources, a further optimisation of DI-diesel engines regarding fuel consumption and exhaust emissions is necessary. Current discussions on the application of different injection systems for passenger cars (distributor pump, common-rail, …) are also of great significance with regard to heavy-duty vehicles. Optical measurement techniques are a valuable tool to evaluate the quality and the potential of modern DI-diesel injection systems. In this work a conventional heavy-duty engine (MAN) was modified to carry out optical investigations inside the combustion bowl, concerning spray propagation and flame luminosity for different injection nozzles. With respect to the current discussions, it was equipped with a modern common-rail system.