Browse Publications Technical Papers 2004-01-1948

A New Application of the Particle Image Velocimetry (PIV) to the Air Entrainment in Gasoline Direct Injection Sprays 2004-01-1948

This experimental work is linked to the recent development of Gasoline Direct Injection engines and is dedicated to the study of the airflow entrained by the hollow cone spray issued from an injector for Gasoline Direct Injection engines. This spray is a dense unstationary two-phase flow that interacts with the surrounding air. The mechanism of air entrainment, due to the momentum exchange between the spray drops and the gaseous phase is an important phenomenon responsible for droplets vaporisation and mixture formation. The latter are directly linked to the reduction of fuel consumption and pollutant emissions.
By application of the PIV technique, measurements of air velocity near the spray edge have been performed and used to compute the mixing rate q in the spray, by mass conservation through a cylindrical control surface (q is defined as the ratio between the mass flow rate of entrained air and the liquid mass flow rate injected).
The influence of two parameters on q is studied. The first one is the injection pressure (Pi) effect, Pi varying from 30 to 90 bars at ambient pressure. The second one is the effect of the chamber back pressure (Pc) Three values of Pc are investigated: 1, 5 and 8 bars for Pi = 80 bars.
Thanks to these results, air entrainment mechanisms in Gasoline Direct Injection spray have been discussed.


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