Measurements of temperature fluctuations in a large-scale turbulent high-pressure flame using CARS

A mobile CARS system has been used to determine temperatures and their fluctuations in a high pressure combustion test rig with a maximum thermal power of 8 MW. Measurements have been performed in turbulent natural gas and oil flames up to a pressure of 14 bar. A high degree of turbulence and an increased pressure together with an extended size of the combustion chamber caused beam propagation effects to become a serious problem for this measuring technique. Temperature determinations in sooty oil flames became even more difficult due to the strong absorption of a part of the fundamental band of the N2 CARS spectrum by C2 radicals. Probability density functions of the temperature, each based on 1000 single shot measurements, have been determined at different radial and axial locations within the combustion chamber.