Brush seals are a strong alternative to conventional labyrinth seals in nowadays turbomachinery applications, especially regarding their superior sealing performance and the increasing fuel costs. Although there has been research regarding sealing performance during the last years, there remains the need to further research in respect of implications which arise with rotor-seal rubbing, mainly concerning heat input into shaft configurations and the effects of wear. Within the framework of a research project of FVV (Forschungsvereinigung Verbrennungskraftmaschinen), a former MTU testrig has been granted to ITS (Institut für Thermische Strömungsmaschinen, Karlsruhe Institute of Technology), and was redesigned to a modern brush seal testrig. Focal point of the new test rig is the possibility to vary rotorseal overlap, and hence to simulate the rubbing behaviour of real applications inside the testrig. Variation of overlap was implemented by axial shifting of the seal over a conically shaped rotor disc. Moreover, the newly manufactured test rig is capable of radial brush seal traverse without major changes to the rig design. In contrast to present literature, in this project heat input of the brush seal is measured with the help of a thermocouple-instrumented rotor disc and a telemetry system, which gives information about transient heat-up of the rotor volume. Detailed finite-element analyses has been carried out for rig design, as for determination of the suitable type of measurement, and structural rotor analysis. The calculation of the heat input of the brush seal into the rotor will be accomplished by means of comparison between the temperature readings with a thermal analysis of a close to reality FEmodel of the rotor. The test rig is fully installed, the FE-analyses have been prepared in advance, so calculation of brush seal heat input can be accomplished at the same time, as the measurements commence.
Bürstendichtungen: Anstreifverhalten und Leckagebestimmung von Bürstendichtungen in Turbomaschinen
FVV Heft 917-2010;