Abstract: A hot gas turbine wheel shroud ring, for hot gas turbine engines, is adapted to be concentrically positioned around the periphery of a row of buckets or blades on the circumference of a turbine wheel to provide a predetermined small sealing and running clearance between the tips of the turbine blades and the ring. The shroud ring is characterized as incorporating certain opposite warping or deflection characteristics from those found in shroud rings under normal high temperature operating conditions.

Abstract: A system is provided inside a turbomachine for controlling operational clearance between a turbine rotor and a surrounding turbine shroud. The system comprises a plurality of control rings, integrated into the turbine casing, that are thermally expanded and contracted to control radial positioning of the turbine shroud. Compressor air is directed through internal passages in the rings to cause the expansion and contraction. The system utilizes the pressure and temperature of compressor air, in combination with size, location, and structure of the control rings to match thermal growth of the control rings and turbine shroud to thermal growth of the turbine rotors, thereby controlling clearance.

Abstract: The electrode of an electrodischarge machining apparatus has a plurality of teeth which are substantially laterally tapered to increasing width toward the machine-held base end. Further, the plane of the tapered portions is inclined to that of the free end portions, which precede the tapered portions in application to the airfoil surface to be machined. As the tapered and inclined portions are inserted into the airfoil surface, a plurality of holes are formed which are diffused in both lateral directions and in one longitudinal direction to thereby provide a diffused hole with improved film cooling effectiveness.