Study on Flow Characteristics in Rotor Disk Rim Seal of Gas Turbine (Effects of Uneven Velocity Profile in Turbine Main Flow)

In advanced gas turbines, it is one of the most important subjects to cool effectively turbine disks as well as turbine blades with the minimum flow rate of cooling air. For the design point of view, detailed information on the slit flow between the rotor and stator including the rim seal is required in order to determine the optimum flow rate of the cooling air and predict the disk temperature distributions on the rotor and stator disks. The present study carefully examines the velocity profiles through the rim seal by measurements using Particle Image Velocimetry (PIV). A simplified experimental apparatus is used for the measurement, which involves a rotor and a rimed stator with a through-flow between them and a main flow surrounding their peripheries. The flow corresponding to the main hot gas usually possesses uneven velocity profile because of the combustion chambers and/or stator blades located upstream. Therefore, the effects of this uneven distribution of the main flow on the rim seal flow have been investigated along with the effects of through-flow rate. Numerical analysis for the flow and temperature fields in the rim seal has been also conducted based on CFD, for the wide range of Reynolds number based on the main flow. The calculated results indicate the scale effects on the flow in the rim seal, namely that the unevenness of the main flow brings about larger effects on the rim seal flow with the increase of Reynolds number.