Enhanced Experimental Measurements of a Gas Turbine Compressor Rotor Analogue Undergoing Thermal Bow

摘要

After shutdown, gas turbine engines will develop a vertical thermal gradient due to natural convection heat transfer in the compressor. This thermal gradient results in uneven thermal contraction of the compressor, resulting in thermal rotor bow. A body of research by the authors has used numerical methods to study the parametric root causes of this phenomenon, with a branch of this research program focused on experimental measurement of rotor bow for the purposes of validation. This study discusses the most recent iteration of the experimental setup, which has improved upon previous versions. A semi-enclosed steel shaft, mounted on a support frame with bearings, is heated to a uniform initial temperature of 600 K via rotation in close proximity to heat guns, inside an insulated box. This method of heating was developed after previous studies concluded that heating the model in an oven was unable to produce a uniform temperature profile. Uniformity of the temperature profile is measured with a thermographic camera. Distortion measurements are taken using two laser profile scanners. After investigating and addressing several sources of uncertainty in the experiment, the final results showed good agreement with the numerical simulation, matching the predicted rotor bow severity and peak time. These results, while imperfect, demonstrate the feasibility of the experimental method, and provide limited validation of the numerical approach used by the authors in the broader research program.