Characterization of Lean Burn Module Air Blast Pilot Injector With Laser Techniques

Abstract

For lean burn combustor development in low emission aero-engines, the pilot stage of the fuel injector plays a key role with respect to stability, operability, NOj¡ emissions, and smoke production. Therefore it is of considerable interest to characterize the pilot module in terms of pilot zone mixing, fuel placement, flow field, and interaction with the main stage. This contribution focuses on the investigation of soot formation during pilotonly operation. Optical test methods were applied in an optically accessible single sector rig at engine idle conditions. Using planar laser-induced incandescence (LII), the distribution of soot and its dependence on air/fuel ratio, as well as geometric injector parameters, was studied. The data shows that below a certain air/fuel ratio, an increase of soot production occurs. This is in agreement with smoke number measurements in a standard single sector flame tube rig without optical access. Reaction zones were identified using chemiiuminescence of OH radicals. In addition, the injector flow field was investigated with PIV. A hypothesis regarding the mechanism of pilot smoke formation was made based on these findings. This along with further investigations will form the basis for developing strategies for smoke improvement at elevated pilot-only conditions.

Investigation of soot formation in pressurized swirl flames by laser measurements of temperature, flame structures and soot concentrations

“…Experimental characterization of turbulent sooting flames either focuses on sub-processes [1,2], or quickly becomes too complex to serve for model validation. Very complex technical cases like fully-technical or industrial combustors [3], are rather used to monitor the overall behavior. Modeling of such cases is possible [4] but frequently lacks sufficient knowledge about the boundary conditions.…”

On the Flow Structure and Dynamics of Methane and Syngas Lean Flames in a Model Gas-Turbine Combustor

“…However, such measurements are quite expensive and difficult for real combustion chambers due to several reasons, including strong vibrations and limited optical access. Therefore, the impact of different processes on unsteady flow and flame dynamics is performed for research combustion sectors, which are equipped with observation windows, allowing for detailed optical measurements and modeling basic phenomena in real combustors [15][16][17][18][19][20][21][22]. Nowadays, planar optical methods like the particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF) have become very popular for the measurements of flow structure and dynamics and for the analysis of flow/flame interactions [23][24][25][26].…”

“…There are also a number of papers for dual swirlers of more sophisticated designs, e.g., LPP (lean premixing prevaporizing, [51,52]) and PERM (partially evaporated, rapidly mixed, [53,54]) injectors by Avio or so-called BIMER experimental setup [55,56]. There are also some studies for triple swirlers [57][58][59] and for realistic burners, like different lean premixed prevaporized injectors (see studies in cooperation with General Electric [18,20], Rolls-Royce [17,19,22,60], Jaxa [45], and other companies [61,62]) and lean premixed burners by Siemens [21,63].…”

Development of a turbulent liquid flux model for Eulerian–Eulerian multiphase flow simulations

“…Hence, several example of lean burn injectors have been developed in the last years (Meier et al, 2013;Mongia, 2003;Buelow et al, 2006;Hernandez et al, 2015). The Injector exploited in the GE-TAPS (Twin Annular Premixing Swirler ) combustor, which currently represents the only lean burn combustion system employed on a certified aircraft engine (GEnX family), is particularly relevant (Mongia, 2003;Li et al, 2010;Cooper et al, 2002;Foust and Mongia, 2007).…”