Fundamental investigations of the heat transfer and the the turbulent flow in convection cooled gas turbine blades

• Applicant: Professor Dr.-Ing. Peter Jeschke
• Subject Area: Hydraulic and Turbo Engines and Piston Engines
• Term: from 2015 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 268575329

Modern stationary gas turbines with highest efficiencies reach turbine inlet temperatures up to 1500 °C whereas the used high temperature materials in today´s gas turbines tolerate only temperatures up to 1000 °C. This temperature difference can only be overcome by cooling of the thermally burdened parts, especially of the turbine blade.The cooling air is taken from the compressor and therefore can no longer be used for the combustion and the expansion in the first stages of the turbine, therefore a higher amount of cooling air leads to losses in the total efficiency. Hence it is necessary to reduce the cooling air flow and use it as efficient as possible.The aim of this project is the investigation of the complex flow and the heat transfer processes in a convection cooled gas turbine blade.The primary purpose of the submitted proposition is to provide a coupled experimental and numerical procedure which uses the integral heat transfer of the cooling channels measured in sections and enables a distinct enhancement of the prediction of the heat transfer.Therefore one sub-ordinate target is the quantification of the uncertainties which arise out of the application of classical heat transfer correlations inside the cooling channels of FEM based methods. Therefore the flow field and temperature field in the inflow and outflow of the section equipped with turbulators and the bends will be measured by traversing with probes and hot wires inside a real cooling channel geometry. Thus the single influences of the turbulated sections as well as their series connection can be investigated. So the classical correlations gained by experiments with simple geometries can be compared with integral heat transfer measurements in a real cooling channel geometry.Another sub-goal is to evaluate the ability of the whole FEM based method with section wise exact heat transfer correlations. Therefore the numerical results of the FEM based methods will be compared to experimental data gained at a hot gas cascade test rig under real engine conditions.In this project as far as we know for the first time all three parts of a FEM based methods will be investigated under the same conditions and are therefore directly comparable and will be published in the open literature: a) the exact measurement of a cooling channel geometry in the cooling air test rig, b) the FEM based method with the correspondent heat transfer correlations and c) the validation under real temperature conditions. Hence the naturally different strengths of the diverse components will be merged to an integral result.

• DFG Programme: Research Grants