Investigation of vapour phase

Kurzfassung

The investigation of the vapour phase is performed on the air-fuel nozzle with swirl cup concept developed for the Task 4.7 of the LOPOCOTEP programme. Twelve different operating conditions including several module configurations and static pressures at constant ALR have been investigated with the IR extinction technique. A first part of the report describes the basics of this method. A stationary analysis performed downstream the injector provides the axial and radial profiles of relative vapour concentrations. These results come as a complement to previous experiments performed by J. Becker [1] on the two-phase flow in the frame of the same programme. A spectral analysis reveals the presence of discontinuities in the spray in terms of droplet density and in the resulting mixed jet in terms of equivalence ratio, that are axially transported by the flow. Four distinct modes are identified, which amplitudes involve less than 1 % of the injected mass fuel flux. The report ends with a discussion on the type of observed fluctuations, their origin, their favourable conditions and their possible incidence on the combustion process at real engine conditions.