Future Trends in Commercial Aviation Engines’ Combustion - Novel Combustion Concepts for Sustainable Energy Development - page 137

Fig. 24 A typical single annular TAPS combustor; from Mongia ( 2003 )

extension of the swirl-venturi lean direct injection (SV-LDI), Sect. 6 or even low-
swirl burner (Therkelsen et al. 2012 ).
The main fuel turned on at the intermediate to high power comprises of single or
multiple swirlers in co- or counter-rotating arrangement along with discrete liquid
jets with or without coaxial air injected into

producing partially premixed
fuel/air mixture for interaction with three distinct external

“ cavity ”

flow regions including
the pilot, the annular gap between the pilot and main exit, and the outer expansion
regions near the wall and circumferential between the cups. The

fl

”
main concept is intended to morph into robust design similar to Sanborn et al.
( 1983 ) as engine OPR increases beyond certain critical value in order to ensure
absolutely no incidence of

“ cavity premixing

fl flashback, autoignition, and/or fl flame holding with

attendant hardware integrity concerns.
In summary, the second generation lean domes have three primary functional
features, namely twin-annular

fl flames; degree of premixing of these fl ames are

optimized for meeting all design requirements; and finally these fl flames are swirl-

stabilized, TAPS. Only one of the three secondary flame regions (viz. pilot/cyclone

interaction region in Fig. 23 ) has been shown in different publications (Mongia
2003 ; 2011e ; Foust et al. 2012 ). The other two regions play an important role in
regard to dynamics, durability, and

fl

fl flame propagation.