Experimental and numerical investigation of self-excited combustion oscillations in a scaled gas turbine combustor

The Prediction and Control of Combustion Instabilities in Industrial Gas Turbines (PRECCINSTA) project, financed by the European Commission Fifth Framework, concerns prediction and control of combustion instabilities in tubular and annular gas turbine combustors. One work package within the PRECCINSTA project joins DLR, CERFACS, and Turbomeca to study turbulence chemistry interaction fundamentals as follows. Turbomeca has a low emissions industrial gas turbine injector that exhibits regimes of unsteady behaviour at engine conditions. A derivation of this injector was designed for the scaled conditions and delivered to DLR for detailed non-intrusive measurements. This injector repeats the unforced unsteady behaviour. The detailed measurements will also serve to validate the latest large eddy simulation (LES) calculations by CERFACS. The non-intrusive measurements capabilities of DLR include: Spectroscopic techniques using pulsed lasers to provide temporally and spatially resolved measurements of flame structure, temperature and composition, planar laser-induced fluorescence (PLIF) of radical species like OH or CH allows qualitative visualisation of flame structure and location, heat release or mixing regions, and laser Doppler velocimetry (LDV). CERFACS is at the leading front of LES with their AVBP flow solver. The key feature of this flow solver is that it resolves the unsteady, reacting and compressible equations of the fluid mechanics and thus takes into account the acoustic phenomena. This enables to simulate the coupling between the turbulent flame and the acoustics, which is known to be the fundamental mechanism of combustion instabilities.