Abstract: A thermal control apparatus is provided for gas turbine engine cases and particularly for thermal control of clearances between turbine rotors and surrounding shrouds. Thermal control of an annular case section or ring is provided by counterflowing two heat transfer fluid flowpaths in heat transfer communication with the section of engine casing. The flowpaths may be in parallel or series such that there is substantially no circumferential gradient in the mass flowrate weighted average temperature of the heat transfer fluid supplied by the two counterflowing fluid flowpaths. One embodiment provides forward and aft rings cooled by three spray tubes in each of two 180.degree. sectors whereby the forward and aft spray tubes flow thermal control air flowing in one circumferential direction and the middle spray tubes flows thermal control air in an opposite circumferential direction.

Abstract: An interference fit up for an HPT hanger is accomplished by machining and casting features into the hanger which create a spring effect when the hanger is assembled into the support. The spring effect may be accomplished in a variety of ways, including offset radial cut features on the hanger relative to the support, or offset projection features on the hanger which are concentric with the support. The spring effect is then accomplished by a flex or deflection of the ends of the hanger to conform to the width of the support, and clearance indentations created during the installation.

Abstract: To cool the shroud in the high pressure turbine section of a gas turbine engine, high pressure cooling air is directed in metered flow to baffle plenums and thence through baffle perforations to impingement cool the shroud rails and back surface. Impingement cooling air then flows through elongated, convection cooling passages in the shroud and exits to flow along the shroud front surface with the main gas stream to provide film cooling. The baffle perforations and the convection cooling passages are interactively located to achieve maximum cooling benefit and highly efficient cooling air utilization.

Abstract: To cool the shroud in the high pressure turbine section of a gas turbine engine, high pressure cooling air is directed in metered flow through channels, which include tapered enlargement frustroconical recuperators, to baffle plenums and thence through baffle perforations to impingement cool the shroud rails and back surface. The baffle perforations and the convection cooling passages are interactively located to achieve maximum cooling benefit and highly efficient cooling air utilization.

Abstract: A cushion having an oblique upper surface adapted to be interposed between the underside of a plucked string instrument such as a guitar or lute and thigh of the performer to facilitate positioning of the instrument at the proper oblique position and height for classical playing. The cushion is partially filled with styrofoam globules so as to enable shaping of its contour to the curved underside of the sound box of the instrument as well as to the profile of the thigh of the performer. The oblique upper surface is made from a vinyl plastic material so as to prevent any slippage between it and the sound box, the bottom surface is made from a napped fabric to prevent slippage on the clothing of the performer and straps are provided to enable the cushion to be strapped around the thigh.