Session: 05-04: Thermal Measurements

Paper Number: 152462

Endoscopic Imaging Enhancement for In-Situ Diagnostics of Irreversible Thermochromic Paints in High Pressure Turbines 

To achieve higher efficiency, turbomachinery components are often operated close to the thermal stress limits of the used materials. Thus, it is of great importance to have accurate knowledge of the temperature distribution across each part to ensure reliability and prevent material failure. Even small changes in temperature can significantly impact the service life of these highly stressed parts. Therefore, precise measurement of temperature distribution on hot-end components, such as turbine blades, vanes and casing parts, is crucial for the validation process of gas turbines. This can be achieved using irreversible thermochromic paint. It reacts sensitively to temperature and time, altering its colour, structure and shine. To avoid disassembling the engine for post-test component analysis, current research is enhancing the use of endoscopic imaging devices for diagnostics involving this temperature-sensitive paint. However, challenges such as inconsistent illumination, limited resolution and failure to account for the paint's structure and shine can significantly increase measurement uncertainty.

This paper develops a methodology to mitigate measurement uncertainty. Firstly, it evaluates the failures associated with endoscope measurements, concentrating on aspects such as geometrical distortion, colour fidelity and colour constancy. To facilitate this, endoscope images are taken in a calibration rig with standardised test specimens under controlled conditions. Secondly, a correction methodology is developed and validated within a high-pressure turbine rig to address these identified failures. The correction methodology comprises of an optimisation of the image acquisition process and application of image processing algorithms and techniques. The proposed approach intends to enhance the analysis of temperature-sensitive paint measurements through endoscopic imaging, thereby improving overall process efficiency and contributing to safer product development.

Presenting Author: Robert Kossakowski Rolls-Royce

Presenting Author Biography: 02/2017 – Present Rolls-Royce, Development Engineer, Experimental Engineering
10/2015 – 06/2016 The Boeing Company, Trainee, Propulsion Wide Body Stress
04/2015 – 10/2015 Volkswagen, Internship, Experimental Aerodynamics
07/2010 – 03/2015 Rolls-Royce, Working student, Engine & Flight Test
10/2013 – 10/2015 Technische Universität Berlin, MSc, Aeronautics and Astronautics
03/2010 – 10/2013 Technische Universität Berlin, BSc, Transportation Systems

Authors:

Robert Kossakowski Rolls-Royce
Dahn Wunderlich Rolls-Royce
Benjamin Endrulat Technische Universität Dresden
Stefan Gier Rolls-Royce
Matthias Voigt Technische Universität Dresden
Ronald Mailach Technische Universität Dresden