COMBINED EXPERIMENTAL - NUMERICAL APPROACH FOR THE FUEL JET STUDY IN A LPP COMBUSTOR

The purpose of the paper is the investigation of the phenomena that mainly affect the mixture preparation and the combustion development in lean-premixed chambers supplied with liquid fuels (LPP). In such a study, the experimental analysis, performed by PDA based measurements, is supported and addressed by a CFD tool that is able to simulate the injection conditions, by isolating and studying some specific phenomena. A 3-D fluid dynamic code (i.e., the FLUENT® flow solver) has been used to simulate the spray pattern in the chamber. Preliminarily, the numerical simulation refer to cold flow conditions, in order to validate the estimation of the fundamental spray parameters through the comparison with the experimental data; in a second step, the calculations employ boundary conditions close to those occurring in the actual combustor operation, in order to predict the fuel vapour distribution throughout the premixing chamber. In particular, the fuel is injected under the typical conditions that occur in the injection system of a gas turbine LPP combustor. In this phase, the experimental information are introduced in terms of air and fuel mass flow rates and of inlet characteristics of the air flow entering the prevaporizing chamber, in order to predict the fuel vapour formation and distribution. The paper also compares different approaches that have been experienced for the CFD simulation.