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" Investigation of Ignition in Sub atmospheric Conditions"

This work is part of the "SOPRANO" EU project.

Motivation

The ability to re-ignite after flame extinguishing is critical for flight safety. One reason that makes difficult the relight process of the engine is the low temperature and low pressure, which slows the evaporation of the atomized fuel and limits the concentration of the oxygen and therefore the reaction rates.

The better understanding of the re-ignition process has a fundamental importance for the development of combustion champers for jet engines, since it allows the combustion chamber to be reduced, thus reducing C0₂ emissions due to the smaller engine mass.

In addition, the transition from RQL (Reach Quench Lean) concept to LPP (Lean-Premix-Prevapourised) has turned the scientific community to intensive research on the ignition phenomena because of the decreasing of residence time in the primary zone due to the increasing amount of the combustion air mass flux (up to 60% of the overall air) which is required for a lean NO_X combustion and makes the ignition process a real challenge.

Aim

The ISCRA rig developed by KIT in the European project KIAI will be used. The design of the rig allows the generation of high altitude conditions at variable flow velocities and turbulence characteristics and provides an optical access for ignition recording by a CCD camera.

During "SOPRANO" project, the investigation will be performed using a 1 sector rectangular combustor with a realistic fuel injection system. This combustor will include geometrical “flexibility” in order to be able to operate with or without wall film cooling. Performing relight experiments with or without film cooling, the ignition capability for  these configurations will be evaluated.

By the relight experiments the Minimum Ignition Energy(MIE) for flame kernel generation and propagation will be measured