This study evaluates the impact of typical cooling hole shape variations on the thermal performance of fan-shaped film holes. A comprehensive set of experimental test cases featuring 16 different film-cooling configurations with different hole shapes have been investigated. The shape variations investigated include hole inlet-to-outlet area ratio, hole coverage ratio, hole pitch ratio, hole length, and hole orientation (compound) angle. Flow conditions applied cover a wide range of film blowing ratios M=0.5 to 2.5 at an engine-representative density ratio DR=1.7. An infrared thermography data acquisition system is used for highly accurate and spatially resolved surface temperature mappings. Accurate local temperature data are achieved by an in situ calibration procedure with the help of thermocouples embedded in the test plate. Detailed film-cooling effectiveness distributions and discharge coefficients are used for evaluating the thermal performance of a row of fan-shaped film holes. An extensive variation of the main geometrical parameters describing a fan-shaped film-cooling hole is done to cover a wide range of typical film-cooling applications in current gas turbine engines. Within the range investigated, laterally averaged film-cooling effectiveness was found to show only limited sensitivity from variations of the hole geometry parameters. This offers the potential to tailor the hole geometry according to needs beyond pure cooling performance, e.g., manufacturing facilitations.
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.
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