Reduced windage high pressure turbine forward outer seal

摘要

A blocker and swirl inducer hole configuration for use in connection with a high pressure turbine is described. In one embodiment, the blocker holes are oriented to a 45-degree tangential angle with respect to the direction of rotation of the seal, which results in pre- swirling the air before being injected into the swirl cavity. In addition, the number of blocker holes is reduced by as much as 50% of the number of blocker holes used in the known CFM56 turbine. Further, rather than injecting the air into the first swirl cavity as is known, the air is injected into a second swirl cavity. The combined effect of orienting the holes to the 45- degree tangential angle with respect to the direction of rotation of the seal, locating the holes to open into the second swirl cavity, and reducing the flow area by about 50%, results in an increase in blocker hole pressure ratio. Increasing the blocker hole pressure ratio results in a higher hole exit velocity which maximizes the cavity inlet swirl. The blocker holes therefore not only provide back-pressure, but also function as swirl-inducers. By inducing swirl into the air injected into the second swirl cavity, better turbine disk rim cooling effectiveness is provided. This result facilitates maintaining reasonable metal temperatures at increasingly severe cycle conditions without the normally expected engine performance penalties.