Design and analysis of high speed wear test rig and wear characterization for brush seals

Brush seals used in steam and gas turbines have an importance in turbine components that increase turbine efficiency. In recent years, brush seals have started to be preferred instead of labyrinth seals in many applications. In this thesis, a test rig for brush seal materials evaluation has been developed so brush seal wear performance is detemined. The final design, CAD modeling, analysis and wear characterization for high speed wear test rig have been studied and detailed within the content of this thesis. The main purpose of high speed wear test rig is to measure the wear rates in order to predict the wear performance on the seal of wires. From a material point of view, the test is performed to evaluate the wear property of the brush seal material so as to determine the long term seal performance and life. The contact between the brush seal wires and their mating counter surface is conducted by testing the small test specimen seal piece of wires against the outside diameter of high speed rotating rotor. The two counter test specimen brush seal is pushed with a specified load from the right and left side of the rotor in order to calculate the wear rates. The test rig provides the capability to measure the wear rates of the wires. The test condition of surface speeds approximately 120 m/s, temperatures between 25℃ and 650℃, and loads 0.2 to 10 N enables the simulation of many important parameters found in turbine brush seals. The test system is suitable for both hot and cold air environment. The furnace is used to heat the system for calculating the wear rates. The tests are conducted applying specified force to the rotating shaft on the radial direction of the seal test specimen and the mass loss of the seal test specimen, which is a convenient method for wear measurement, is measured by using precision balance. In other words, wear rates are calculated due to the mass loss under unit applied force. The different effects on brush seal wear characteristics have been investigated such as the effect of temperature, surface velocity and the rotor material. Moreover, thermal and mechanical analyses of the critical rotating parts which are used in system are conducted so that the design verification has been achieved. Results show that, the brush seal wear coefficient decreases with the increasing surface speeds of contact region. In addition, it tends to decrease with the increasing temperature and the brush seal bristle wear is dependent on rubbing material type.