Fierce international competition for efficient power plants and vehiclepropulsion systems has fuelled evolution of gas turbines over the last eightdecades of production. Power output can be increased with Turbine EntryTemperature (TET), which can typically be 500K higher than the melting pointof turbine components. Safe engine operation in such extreme conditions ispartly ensured by coating turbine components with a film of coolant air. Anadditional 1% in coolant air flow can raise TET by 100K at a 1% penalty inengine efficiency. Determining coolant quantities for optimum cooling istherefore key to maximising engine thrust, efficiency, and component life.Experiments conducted on models at engine-representative conditions canaid the development of more efficient cooling methods, in addition to thevalidation of Computational Fluid Dynamic modelling codes. Thermalvisualisation techniques will also aid in this assessment (e.g. ThermochromicLiquid Crystals, or Infrared Thermography).The focus of this study is the assessment of applications and limitations ofInfrared Thermography in turbine cooling flow visualisation. A model of aturbine blade leading edge with showerhead film cooling has beenconstructed and operated at an engine-representative Reynolds number in alow-speed wind tunnel. The coolant gas has been pre-heated prior to ejectionand an Infrared camera was used to acquire coolant jet thermal imprints overthe model surface in order to assess cooling effectiveness for differentBlowing Ratio values. A perpendicular fine nylon mesh was used to capturecoolant plumes at different circumferential locations above the cylindersurface to assess the extent of jet lift-off and interaction with cold mainstreamflow. MATLAB software was used to develop camera calibration and dataprocessing codes. The results have been used to assess the experimentaltechnique for accuracy and consistency, as well as ability to make accurateheat transfer, or cooling effectiveness measurements.
|Date of Award||9 Oct 2014|
|Supervisor||Stuart Macgregor (Supervisor)|