Engine with Optically Accessible Cylinder Head: A Research Tool for Injection and Combustion Processes

Abstract

<div class="htmlview paragraph">The upcoming emission regulations for Diesel engines will become more restrictive. This has made it necessary to develop new diagnostic tools and methods that allow to obtain a more accurate knowledge about the chemical and physical phenomena that occur during the atomization, evaporation and ignition of the fuel spray.</div> <div class="htmlview paragraph">This paper describes an experimental setup for injection and combustion research. The system is based on a two-stroke direct injection Diesel engine whose cylinder head is equipped with four optical accesses. Inlet flow can be switched either to nitrogen or to ambient air. In both cases, thermodynamic properties are controlled to reproduce the actual conditions of density, temperature and pressure at the end of the compression stroke in a real engine. A high-pressure common-rail system with an electronic control unit makes it possible to modify injection parameters: pressure, timing, duration and frequency.</div> <div class="htmlview paragraph">Three optical techniques have been employed, namely backlighting, laser-induced exciplex fluorescence and flame natural luminosity imaging, by which a first study of Diesel injection development and early combustion process has been performed.</div>