Effectiveness distributions on turbine-blade cascade platforms through simulated stator-rotor seals

A five-blade linear cascade is used to experimentally investigate turbine-blade platform cooling. Three slot configurations placed upstream of the blades are used to model advanced seals between the stator and rotor. The seal configurations include vertical injection of the coolant onto the platform, a redirection of the coolant onto the platform, and a labyrinthlike configuration between the stator endwall and rotor platform. The coolant flow rate through the seals varies from 0.5 to 2.0% of the mainstream flow. The film-cooling effectiveness is measured on the platform using pressure-sensitive paint. The upstream slots cover 1.5 passages with the coolant exiting the slot 3.87 cm upstream of the leading edge of the blades. The mainstream Reynolds number is 3.1 x 105 based on the inlet velocity and the chord length of the scaled high-pressure turbine blade. With the pressure-sensitive-paint measurement technique, the effect of the passage-induced secondary flow on the film-cooling effectiveness is easily captured, as the distribution of the film effectiveness is very nonuniform through the passage. In addition, the more advanced seal configurations, considered in the present study, yield reduced film-cooling effectiveness compared with the more fundamental inclined slot configurations.

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