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Application of the two-dimensional laser Rayleigh technique to the investigation of a large-scale industrial combustor is reported for the first time to our knowledge. Two-dimensional laser Rayleigh scattering was used to perform quantitative measurements of the temperature fields in different downstream positions of a 150-kW industrial, premixed, turbulent low-emission swirl combustor. Because of the possible interferences of the Rayleigh signal with Mie scattering and laser reflections of the burner components, some minor modifications of the design of the combustor and its gas supply were necessary. This was done without changing the basic characteristics of the burner. The quantitative and instantaneous character of the collected data allows calculation of ensemble-averaged temperature distributions and analysis of the flame structure in the turbulent combustion field. The measured temperature distribution confirms that the flame is stabilized by a central recirculation zone.

The simultaneous application of vibrational coherent anti-Stokes Raman scattering (CARS) and the two-dimensional (2D) UV laser Rayleigh technique is reported for the investigation of a highly turbulent swirl frame inside a contained technical combustor. The CARS technique has been used to determine accurate temperature values at one point within the 2D Rayleigh-probed combustion field. These values were necessary to normalize the Rayleigh data to overcome influences of absorption effects along the detection path of the Rayleigh-scattered light through the exhaust gas volume and by the sealing window of the combustion chamber. At several different downstream positions, 500 simultaneous measurements with the point and with the 2D technique were performed to cover the whole combustion field. These data can be used for both the evaluation of 2D temperature structures in single frames and for the calculation of temperature probability density functions from the Rayleigh data at one single camera pixel over 500 frames. With this information, characterization of a highly turbulent flame is possible.

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