Future Trends in Commercial Aviation Engines’ Combustion - Novel Combustion Concepts for Sustainable Energy Development - page 136

3.2 TAPS Technology and Product Introduction

The formulation of the second generation lean dome technology bene tted from the

lessons learned since the early 1970s including DAC discussed above and the
references quoted; in addition to the two axially-staged combustion technologies
(viz. Bruce et al. 1977 , 1978 , 1981 ; Roberts et al. 1977 , Dubiel 1986 and Segalman
et al. 1993 ); the recuperated automotive gas turbine combustion technologies (viz.
Sanborn et al. 1983 ; Ross et al. 1983 ; Rizk and Mongia 1990 ); and the high-speed
research combustion, US Patent 6530223, March 11, 2003. Almost all of these
approaches except Sanborn et al. ( 1983 ) should have some degree of dif

culty in

meeting the pro le requirement without which turbine stages cannot operate at their

best with attendant fuel burn impact. Therefore, multiconcentric flames technology

development (Fig. 23 ) mostly for applications in SACs (Fig. 24 ) became the focus
of the new initiative sponsored under the NASA Advanced Subsonic Transport
(AST) and the follow-on Ultra Energy Ef

fl

cient Turbine (UEET) programs com-
plimented by GE in-house technology funding.
Different types of pilot con gurations could be envisioned but only a limited

few have been shared through several US patents. Unlike swirl cups, fuel spray is
not intended to impinge on the venturi. The fuel spray from pressure atomizer or
other means including pure or piloted airblast nozzle interacts with the sur-
rounding set of swirlers bounded by at least two annular con

nements to produce

fuel/air mixture fit for performing the low-power operation including ignition and

fl flame propagation and idle to intermediate power setting with the combustion

ef ciency level matching that of the rich domes. Its NO x emission contribution

becomes more critical as one proceeds with mixers producing successively lower
NO x implying application of features that can control degree of mixedness. The
pilot assembly can have co- or counter-rotating swirlers with the overall swirl
strength being very weak, weak, or moderate. One could see the application of
high-swirl inner swirler surrounded by the weak counter-rotating outer swirler. In
summary, the pilot could be interpreted as a swirl cup; some could see it as an

Fig. 23 Conceptual
description of Twin-Annular
partially Premixing Swirl-
stabilized flames (TAPS);
reproduced from Mongia
( 2003 )