Abstract:
A thin film electroluminescent display panel is driven with either a symmetric or asymmetric drive scheme which includes at least one equalizing voltage pulse per write cycle to remove carriers trapped at the interfaces of dielectric layers and phosphor layer in order to stabilize the charge of each display panel pixel. The present invention reduces the smearing, latent image and pseudo persistence problems caused by carriers being retained and accumulated at the dielectric and phosphor layer interfaces.
Abstract:
A process for producing a fine grain forged superalloy article having a high yield strength at intermediate temperatures. A preferred starting composition comprises, by weight, 15 % Cr, 13.6 % Co, 4.1 % Mo, 4.6 % Ti, 2.2 % Al, .01 % C, 0.007 % B, 0.07 % Zr, balance Ni. This material is forged at a temperature above the gamma prime solvus and at a true strain of at least .5. Alternately, the material may be forged below the gamma prime solvus temperature with intermediate super solvus anneals. The overaged material is then worked at a temperature below the gamma prime solvus. The resultant fine grain material is then heat treated or can be further isothermally forged prior to heat treatment to produce complex shapes.
Abstract:
A metal nitride powder can be made by heating a reactant powder that includes an oxide or hydroxide of Al, Ti, or Zr to a reaction temperature in a nonreactive atmosphere. The heated reactant powder is contacted with a gaseous reactant mixture comprising a nitrogen source and a carbon source. The molar ratio of nitrogen to carbon in the gaseous reactant mixture is at least about 15. The reactant powder is maintained at the reaction temperature for a sufficient time to convert a portion of it to metal nitride powder.
Abstract:
A rotor blade balance weight assembly comprises a weight retention housing (10) having a hollow core (22) and being closed on one end (12). The housing is disposed in an aperture which extends from the upper (52) to the lower (53) airfoil surfaces of the rotor blade (50). The closure end of the housing is contoured to match the airfoil upper surface contour. A stud (70) extends along the central axis of the housing, and washer-like balance weights (72) are received over the stud and secured by a locking nut (75). The open end of the housing is closed by a cover plate (25) that is contoured to match the airfoil lower surface contour, the cover plate being secured to the housing by a nut (78) in locking engagement with the stud. A pair of clips (37) are received within the housing, each clip having a tab suface (40) which extends through slots (42) in the housing, the clips being secured by the locking nut and stud. The cover plate and housing closed end are counter sunk (17, 59, 27) to provide a smooth airfoil surface.
Abstract:
An outer air seal assembly (44) cooled by a combination of impingement cooling and film cooling is disclosed. Various construction details are developed which provide impingement of cooling fluid on a radially outer side of an outer air seal assembly (44) and ejection of a film of cooling fluid over a radially inner surface (52) of the outer air seal assembly (44). In a particular embodiment, an outer air seal assembly (44) includes a substrate (54), an apertured cover (56) disposed outward of the substrate (54), and a layer of abradable material (58) extending radially inward of the substrate (54) and defining a flow surface (52). Cooling fluid is directed through the apertures (72), into a cavity (66), and impinges upon the outer surface of the substrate (54). A plurality of film cooling holes (76) extend through the substrate (54) and abradable layer (58) and provide fluid communication between the cavity (66) and flowpath (14). The cooling holes (76) are oriented to eject cooling in a film over the flow surface (52). In another embodiment, the cavity (66) includes a longitudinally extending chamber (112) disposed in an enlarged portion (108) of the air seal (46) to enhance cooling thereof and reduce stresses therewithin.
Abstract:
A rotor blade (44) having axially spaced gussets (72, 78) disposed between a root portion (66) and a platform (64) is disclosed. Various construction details are developed which provide a gusset providing both platform support and damper positioning means. In one particular embodiment, a rotor blade assembly (38) includes a plurality of circumferentially spaced rotor blades (44) having dampers (88) disposed between adjacent blades (44), wherein each blade (44) includes an axially spaced pair of gussets (78, 82) extending laterally from the rotor blade (44). The gussets (78, 82) extend from a root portion (66) of the rotor blade (44) to a platform (64) and provide radial support of the platform (64) during rotation of the rotor assembly (38). The gussets (78, 82) include a curved lateral edge which, during rotation of the rotor assembly (38), urges the damper (88) away from the root portion (66) of the blade (44).
Abstract:
An integrated damper and windage cover (52) has a windage cover portion (56) cantilevered at the upstream end, free of contact with the blade platform (24, 32). The contact portion (54) is rigid and bears against the underside of the blade platform (24), spanning blade platform clearance (50).
Abstract:
A pressure regulating flow control apparatus comprises a flow metering valve (10) for controllably discharging a fluid from a spring-biased throttling spool (30) thereof to a fluidic device at a regulated pressure and a pressure modulating valve (100) operatively associated with the throttling spool (30) of the flow metering valve (10) for modulating the fluid pressure in subchamber (18) of the metering valve (10) to alter the position of the throttling spool to adjust the regulated pressure in response to fluid temperature over a relatively large temperature range so as to compensate for the variation of fluid viscosity with fluid temperature.
Abstract:
A sealed assembly (46) for a rotary machine (10) is disclosed. Various construction details are developed which block the migration of oil from a compartment such as a bearing compartment (22). In one detailed embodiment, an annular clearance gap (G) is provided with an outwardly tapered surface (98; 118; 98, 118) to energize a boundary layer or to block lubricating fluid from migrating from the bearing compartment.
Abstract:
A drive system for varying the diameter of a variable diameter rotor has a gear assembly associated with a single coaxial shaft (13) lower end which includes a gear set for increasing the speed of rotation of the central shaft (13) relative to the rotor drive shaft (2) to change the diameter of the variable diameter blades. A pair of brakes are used, one (37) to slow the coaxial shaft relative to the drive shaft and another (25) to lock the rotor shaft (2) and coaxial shaft (13) together for corotation during constant diameter flight conditions. Utilizing a lower gear assembly reduces hub complexity and allows the variable diameter rotor drive system to be adapted to gimballed rotors which require shaft flexibility. Since only a single shaft extends through the rotor drive shaft, hub complexity is reduced.