High-pressure Diesel spray temperature measurements using two-colour laser-induced fluorescence

Abstract

This paper presents a new implementation of an optical technique which aims to measure the temporal and spatial evolution of the liquid temperature of a high injection pressure Diesel spray. Measurements are performed using the two-colour laser-induced fluorescence technique in which a temperature-sensitive fluorescent tracer is added to the fuel (ISO 4113 normafluid in the present case) and all the parameters except the temperature (e.g. tracer concentration, incident laser excitation, droplet number density) are eliminated by processing the ratio of the fluorescence intensity measured on two spectral bands. Diesel sprays, issuing from a single-hole injector, are injected at high pressures ranging from 500 to 1500 bar at a frequency of 10 Hz. The signal acquisition is then triggered on the injection cycle to enable the phase-locked monitoring of the liquid phase temperature. Temperature maps of the spray are presented and the influence of the injection pressure on the droplet temperature can be finally inferred from these results.