Test Rig for Applied Experimental Investigations of the Thermal Contact Resistance at the Blade-Rotor-Connection in a Steam Turbine

December 16-21, 2017 Abstract Studies have shown that in a pre-warming respectively warm-keeping operation of a steam turbine, the blades and vanes transport most of the heat to the thick-walled casing and rotor. Œereby, a boŠle-neck arises at the connection between the blade root and the rotor. Œe contact heat resistance at these interfaces a‚ects the temperature distribution and thus the thermal stresses in the rotor. Œe present paper introduces a thermal contact resistance test rig, which is designed to quantify the contact heat transfer at the blade-rotor-connection of a steam turbine. An uncertainty analysis is presented which proves that the average measurement uncertainties are less than one percent. In addition to the test rig, a numerical model of the specimen for the determination of the thermal contact resistance is developed and introduced. Results of several steady-state measurements under atmospheric and evacuated atmosphere using a highly temperature-resistant chromium molybdenum steel are shown. As a main inƒuence parameter the contact pressure is investigated, which is a‚ected by the rotational speed of the turbine. Œe investigations show a signi€cant contact heat resistance especially at small contact pressures.