Laser-induced incandescence particle size measurements in a heavy-duty diesel engine

Laser-induced incandescence (LII) is a relatively
new experimental method for studying the soot formation
process in flames. LII is based on the quasi-instantaneous heating of soot particles, by means of a high-energy pulsed laser beam, to almost their vaporization temperature, resulting in a strong but transient increase in their incandescence. After the laser pulse the particles cool down, at a rate which is dependent on their surface-to-volume ratio. The decay rate of the laser-induced incandescence intensity thus contains information on the particle size distribution within the irradiated volume. In this communication we report on the characterization of soot by time resolved LII (Tire-LII) measurements in a heavy-duty diesel engine, with peak pressures up to 6 MPa, paying particular attention to the correction required for the finite time resolution of the hardware, and to the role of the initial particle temperature.