Application of Advanced Experimental Techniques in the Development of a Cooled Turbine Nozzle

Abstract

In spite of very significant progress in analytical and numerical methods during recent years, experimental techniques are still essential tools for the development of cooled turbine nozzles. This paper describes the major elements of the development process for cooled turbine nozzles with a primary emphasis on advanced experimental heat transfer techniques. Thermochromic liquid crystals were used to measure the internal (coolant side) heat transfer coefficients of a practical vane cooling design which has a combination of different heat transfer augmenting devices. A comparison of the results and analytical predictions provided validations of existing correlations which were developed from the generic cases (usually one type of augmenting device). The overall cooling design was evaluated in a full-scale annular hot cascade which maintained heat transfer similarity. The freestream turbulence level was measured with an in-house developed heat flux probe. Cooling effectiveness distribution was evaluated from the surface metal temperatures mapped with an in-house developed wide range temperature pyrometer. The test results led to the fine-tuning of the nozzle vane cooling design.

An Infrared Technique for Evaluating Turbine Airfoil Cooling Designs

“…Modern experimental techniques play an important role in this development process, both in preliminary design concept screening and as an important source of validation data for heat transfer design analysis tools (Moon and Glezer, 1996). The present paper describes an experimental approach that combines rapid prototyping of easily tested large-scale flat plate specimens with a highly productive infrared (IR) temperature measurement technique.…”