Abstract
In this work, the RAYLIX measurement technique is applied for the first time in the combustion chamber of a direct injection, heavy duty Diesel engine. This technique is a combination of elastic Rayleigh scattering, laser induced incandescence, and extinction. When applied properly, it can provide spatially-resolved information about soot particle diameters, soot concentrations, and particle number densities in a measurement plane within the engine. Specially designed endoscopic optics are used in combination with an optically accessible heavy duty Diesel engine to evaluate the suitability of this measurement technique as a diagnostic tool in a close-to-production Diesel engine. A low-load operating point is chosen for the first application of the measurement technique. For both Diesel fuel and a Diesel-ethanol-water emulsion, results are presented for EGR rates of 0% and 30%. For the operating conditions presented here, it is demonstrated that EGR delays the onset of soot formation and decreases soot formation early in the combustion. The use of the Diesel-ethanol-water emulsion decreases early soot formation to an even greater extent.
