NUMERICAL AND EXPERIMENTAL INVESTIGATIONS OF COMBUSTION INSTABILITY PHENOMENA IN GAS TURBINE BURNERS FOR HEAVY DUTY AND AERO-ENGINE APPLICATIONS

In the recent years, as the technical developments in the field of GT related technology are more and more driven by regulations on environmental pollution control, a whole series of different industrial evolution and innovation lines are investigated so to make combustion processes ever "cleaner". Among those, there is for sure the adoption of lean and ultra lean combustion processes to be pursued by means of airfuel premixing combustion technologies. Within this scenario, at DIMSET/SCL (Savona Combustion Laboratory, Dept. of Thermal Machines, Energy Systems and Transportation, Univ.of Genoa) since several years research activities are carried out, mainly within the frame of EC-funded Research Programmes (ICLEAC, MUSCLES, TLC, H2-IGCC) and cooperation with industrial companies of the energy sector (Ansaldo Energia S.p.A.) and aero-propulsion (Avio Group) sectors. Research activities can take advantage of a close integration between experimental facilities, such as several reactive and nonreactive dedicated burner test-rigs, instrumented with LDV, PDA and PIV laser-based equipment, as well as of in-house continuously improved reactive Navier-Stokes solvers for combustor analysis (NastComb solver) and design (TPM method). The paper deals with the stability characterisation of the different combustion-processes taking place within several GT power plants, namely, the heavy duty AE64-3A heavy duty gas turbine (Ansaldo Energia), already present on the market, the so-called Liquid and Gas Rapid Pre-Mix burners, LRPM and GRPM, designed at DIMSET/SCL and still prototypical, and the Avio-designed LPP (Lean Premixed Prevaporised) burner, for aero-engine applications. The research has been addressed at in-depth characterising the stability behaviour of the burner's operation. In particular, those aspects have been investigated deemed of greatest importance in affecting a stable performance profile, such as swirlers' design, burner's internal aerodynamics, premixing duct configuration, fuel typology and injection modalities, etc. The paper gives a synoptic view both of the research approaches (experimental, instrumental, numerical analysis and design) jointly pursued by DIMSET/SCL team in investigating the combustion instability, as well as of the obtained results, which help in pointing out those burner design and operational parameters which appear as most critical in affecting instability insurgence and self-sustainment. Copyright © 2011 by ASME.