Zusammenfassung
In
diesem Teilprojekt wird ein Versuchsträger in Form einer modular aufgebauten
Brennkammer mit multi-Brenner-Anordnung realisiert. An diesem Versuchsträger
werden Fragestellungen wie niedrig- und hochfrequente Verbrennungsinstabilitäten,
Schadstoffbildung und Wechselwirkungen Strömung/Verbrennung untersucht. Ziel
sind Skalierungsgesetze für den Aufbau von technischen Systemen und deren
numerische Simulation bzw. Vorausberechnung sowie die Entwicklung einer hochwertigen
Datenbasis. Die einzelnen Brenner werden in anderen Teilprojekten mit
unterschiedlichsten Methoden detailliert experimentell und numerisch
untersucht.
Summary
Non-stationary combustion in internal combustion
engines or gas turbines is the main focus of the Collaborative Research Centre
606, cf. project cluster "Engine Combustion" and project cluster
"Combustion Chamber". Modern combustion concepts for combustion
chambers of gas turbines comprise lean premixed (LP) combustion. On the one
hand lean premixed combustion is implemented as far as possible in stationary
gas turbines (GT), since it allows reducing the production of thermal NOX. Unfortunately
LP combustors are prone to combustion instabilities with both low and high
frequencies. For these reasons and for safety aspects on the other hand
technical combustors are operated "as premixed as possible" by means
of the aerodynamic layout and combining diffusion (pilot) flames with premixed
operation of the major part of the fuel. As an alternative to this the
"rich-quenched-lean" (RQL) concept has been discussed, where the fuel
is converted stepwise under rich and lean conditions and the air necessary for
the dilution to the lean step is used to cool down the hot combustion gases. In
partially premixed flames, diffusion flames and rich combustion conditions soot
is formed intermediately which necessarily has to be oxidised
before leaving the combustion chamber. The intermediately formed soot which
possibly is emitted from the combustion devices forms another problem connected
with technical combustion concept for gas turbines. Furthermore, technical
combustors are requested to comprise fuel flexibility, viz. the utilization of
gaseous and liquid fuels is desired. Premixing of prevaporized liquid fuels brings about the possibility of
combustion instabilities that may be fortified until flash back and also the
problem of soot formation in case of partially premixing.
All together, modern combustion concepts are faced
with the problems of
• low frequency instabilities,
• high frequency
instabilities,
• soot formation and oxidation,
• enhancement of the above problems by the application of liquid fuels.
Low frequency and high frequency combustion
instabilities, utilization of liquid fuels, soot formation and oxidation have
been widely investigated in the past in laboratory scaled devices and model
systems. Scaling laws for prediction of these phenomena when upscaling the combustion device or varying the geometry,
the thermal load, operating pressure or the number of single burners combined
into a technical combustor, however, are for the most part missing. It is,
therefore, the main goal of this subproject to realize a modular combustor
where the above sketched problems can be investigated in substantial detail.
The concept of this combustor is such that the investigation of effects of
scaling up and numbering up of the system,
• effects of aligning the single burners (annular, matrix or linear arrangement),
• application of liquid fuels
on
• low frequency
combustion instabilities,
• high frequency
combustion instabilities,
• soot formation and oxidation,
• pressure variation
can be performed on the single elements as well as
different sized combinations of single burners. The single burners are, furthermore,
investigated in different subproject of the CRC 606 experimentally and
numerically with the most advanced techniques and methods developed in the past
within the CRC. The modular combustor above all serves as a test carrier for
the "combustion family" which complements the facilities available at
other research institutions, e.g. DLR Köln, IVT-DLR Stuttgart, TU-Darmstadt,
RWTH-Aachen, and that are designed for other operating conditions and other
objectives.
The subproject C6(N) is
embedded in the project cluster "Combustion Chambers" where the
subprojects B9(N), B10(N), C1, C7(N), C9(N) and C10(N) are integrated.
