Abstract: A flow directing element, such as a vane for a turbine engine compressor, has a variable chord to improve compressor surge margin without compromising compressor efficiency. The vane has an airfoil section (70) with a leading edge (80), a trailing edge (82), a root (84) and a tip (88). The chord of the airfoil generally increases from a first value at the root to a second larger value at a part span location (110) intermediate the root and the tip so that when the airfoil is installed in a compressor, the location of the trailing edge becomes closer to the compressor discharge as the spanwise distance from the root increases. The chord is generally constant from the part span location to the tip.

Abstract: A turbomachinery blade for use in a turbine blade array, has a suction surface contour featuring chordwisely separated, positively curved forward and aft segments 35, 36 and a negatively curved medial segment 37 chordwisely intermediate the forward and aft segments. When used in an array of similar blades operated in a transonic environment, the inventive blade mitigates overexpansion of working medium fluid flowing through the interblade passages 17. As a result, subsequent recompression of the fluid by an aerodynamic shocks 31, 32 is less severe, and aerodynamic inefficiencies related to the presence of the shocks are reduced.

Abstract: A windmilling brake system for a turbine engine includes a brake drum (14) on an interior surface of an engine rotor. The drum circumscribes a brake unit (37) that includes a brake ring (38) with brake shoes (42) each connected to the ring by respective springs (44). A leg (45) extends from each shoe and toward the ring. The ring is sandwiched axially between bolting flanges (28, 29) on forward and aft carrier portions (24, 25) of a two piece, variable stiffness, dual load path rotor bearing support. Nonsacrificial fasteners secure the ring to one of the flanges while frangible fasteners (52) secure the flanges to each other. The frangible fasteners also extend through an eye (47) in each leg to deflect the springs and hold the brake shoes in an armed state out of contact with the drum. Upon being exposed to abnormal imbalance loads, the frangible fasteners fail in tension to disable one of the two load paths.

Abstract: A fixture for selectively masking a turbine blade 60 includes a locator 10 with a separable receptacle 40 having portals 50. Guide bars 18 extend from the locator for guiding a pair of shield carriers 20 between deployed and retracted positions. Each shield carrier has a shield 26 projecting therefrom. In use, a turbine blade 60, whose root 70 includes a fir tree attachment 72 and a damper pocket 74, is mounted on the fixture so that the receptacle embraces the blade root. The shield carriers are translated along the guide bars until the shields penetrate through the portals and into the receptacle thus segregating the attachment 72 from the damper pocket 74. Masking powder 84 is then compressed into the receptacle to envelop the attachment while leaving the damper pocket unmasked.

Abstract: A coolable vane (12) for a turbomachine includes an airfoil (16) with a pair of imperforate ribs (42, 44) that extend laterally across the airfoil. The ribs have suction side termini (52, 56) and pressure side termini (54, 58). The suction side termini chordwisely delimit a segment SS of the airfoil suction wall (28) so that the ribs and the suction wall segment bound an internal plenum (48) for distributing a pressurized coolant spanwisely through the interior of the airfoil. An array of film cooling holes (84) penetrates the suction wall segment and is the exclusive avenue for conveying coolant from the plenum to a working medium fluid flowpath. Accordingly, relatively low pressure coolant may be supplied to the plenum without the risk of backflow or spanwise discontinuities in the surface cooling film.

Abstract: An axial flow or centrifugal flow compressor having arrays of blades (16) extending across a working medium flowpath (18) includes a casing treatment for enhancing the compressor's fluid dynamic stability. In one variant of the invention the casing treatment comprises one or more circumferentially extending grooves (40) that each receive indigenous fluid from the compressor flowpath at a fluid extraction site (56) and discharge indigenous fluid into the flowpath at a fluid injection site (58), circumferentially offset from the extraction site, where the migrated fluid is better able to advance against an adverse pressure gradient in the flowpath. Each groove is oriented so that the discharged fluid enters the flowpath with a streamwise directional component that promotes efficient and reliable integration of the introduced fluid into the flowpath fluid stream (20).

Abstract: A star configured epicyclic gear train includes a sun gear 10, a plurality of star gears 16 supported on bearings 18, a ring gear 51 and a set of baffles 44 disposed between the star gears. A single lubricant circuit serves as the exclusive means for supplying lubricant successively to the bearings, the sun/star mesh and the star/ring mesh. A variant of the gear system includes an auxiliary lubricant circuit featuring a set of spray bars 82 for supplying lubricant to the sun/star mesh and the star/ring mesh. The primary and auxiliary circuits share a common lubricant discharge path representing the exclusive means for evacuating both the primary and auxiliary lubricant from the gear system. Preferably, the auxiliary lubricant circuit is selectively operable. The inventive gear system addresses a number of difficulties related to lubricating and evacuating lubricant from a star configured epicyclic gear system.

Abstract: A turbine blade (18) for a gas turbine engine includes a machining datum and support tool interface (52). The datum and interface feature is a frustoconical depression residing in a blade outer shroud (36) and ideally aligned with an airfoil stacking line (40). The blade has a prefinished state in which the depression has a prefinished depth and a finished state in which the depression has a finished depth. The finished depth is smaller than the prefinished depth, but is nevertheless sufficient to act as a support feature during manufacturing operations. The utility of the depression, as both a datum and as a support feature, survives the original manufacturing operations so that the depression is useful for post-manufacturing inspection and repair.

Abstract: The invention is a turbomachinery module (10) whose forwardmost vanes, which are the most damage susceptible vanes in the module, are easily removable and replaceable without substantial disassembly of the module. The module includes a case (12) and a forwardmost array (1V) of vanes. Each vane (34) of the forwardmost array has an axially proximal and distal end (90, 92) relative to the forward end (16) of the case. The distal end of each vane has a foot (102) that abuts but is not connected to a vane guide (32) on the case. The proximal end of each vane has an attachment bracket (110) that can be secured to or disengaged from a vane support (28) on the case. Vane removal is accomplished by disengaging the attachment bracket (110) from the vane support (28) and withdrawing the vane through the forward end of the case. The invention improves upon conventional turbine modules in which the forwardmost vane array is removable only from the aft end of the case after the module has been substantially disassembled.

Abstract: The invention is a tangential entry, premixing fuel injector (10) for the combustion chamber (30) of a turbine engine. The injector includes a pair of arcuate scrolls (18) defining the radially outer boundary of a mixing chamber (28) and a pair of air entry slots (36) for admitting a stream of primary combustion air tangentially into the mixing chamber. The scrolls also include an axially distributed array of primary fuel injection passages (42) for injecting a primary fuel into the primary air stream. A flame stabilizing fuel injector centerbody (46) includes an impingement and transpiration cooled outlet nozzle (50) for introducing secondary fuel and secondary air into the combustion chamber. The nozzle (50) includes an impingement plate(74) with an array of impingement ports (76) and a tip cap (104) with an array of discharge passages (106).

Abstract: A tangential entry premixing fuel injector (10) for a gas turbine engine combustor includes a pair of offset scrolls (18) whose ends define a pair of entry slots (36) for admitting primary combustion air tangentially into a mixing chamber (28) bounded by the scrolls (18) and by longitudinally spaced endplates (14, 16). An array of fuel injection passages (42) extends along the length of the slots. The passage array is configured to inject a primary fuel nonuniformly along the length of the air entry slots and to control the fuel penetration depth d in proportion to slot height H. The injector also includes a flame disgorging centerbody (48) having a bluff tip (54) longitudinally aligned with the injector's discharge plane (22) and a secondary fuel conduit (80) extending through the centerbody for discharging a secondary combustible fluid, preferably gaseous fuel, through a series of fuel discharge openings (84) in the tip (54).

Abstract: A method for preparing a protectively coated, apertured article to be recoated reduces the likelihood that the apertures will become constricted as a consequence of subsequent recoating. The invention, described in the context of a gas turbine engine blade (12) having transpiration cooling passages (34), includes the step of diffusing an auxiliary coating (52) into an existing coating (28) and into the exposed substrate material (26) at the periphery of the passages to form a diffusion zone (54). The blade is then subjected to a stripping agent so that the diffusion zone (54) any undiffused existing coating, and any undiffused auxiliary coating are removed. The method causes a compensatory enlargement of the mouth (44) of each passage so that excess coating that accumulates in the passage mouths during subsequent recoating does not restrict the flow capacity of the passages.

Abstract: The invention is a valve seal assembly (43) illustrated in the context of a compressor bleed valve (36) for a gas turbine engine. The seal assembly includes a seal carrier (44) having a circumferentially extending groove (72) bordered by a pair of opposing flanges (74). The flanges cooperate to define a recess (76) portion of the groove and a throat (78) portion of the groove. The seal assembly also includes one or more seal elements (46) each having a base (82), conformal with the recess, and longitudinally captured in the recess by the flanges. A stem (84) extends from the base and projects through the throat, and a sealing bead (86) extends from the stem. An insert (88) extends circumferentially in the base for stiffening the base about a circumferential bending axis (C). An access port (96) facilitates installation and removal of the seal elements (46) and a cover (98) traps the seal elements in the carrier (44).

Abstract: A premixing fuel injector for an industrial gas turbine engine includes an axially extending centerbody (58) and a pair of radially offset scrolls (18) bounding a mixing chamber (24). The leading end (28) of each scroll cooperates with the trailing end (34) of the neighboring scroll to define an intake slot (42) for admitting a stream of primary combustion air (44) tangentially into the mixing chamber. Fuel injection passages extend along each intake slot for injecting jets (76a, 76b) of primary fuel into the incoming airstream (44). The injector is operable in a prescribed or normal state, and in a degraded state associated with the presence of undesirable combustion inside the mixing chamber. The fuel injection passages are oriented and positioned so that the fuel jets issuing therefrom are ineffective at sustaining the undesirable combustion for more than a limited interval of time.

Abstract: A low emissions combustor can 18 for an aircraft gas turbine engine includes a louvered combustor liner 24 with three arrays of dilution holes 52, 54, 56. The first hole array comprises twelve equally sized, equiangularly distributed holes that penetrates the liner about midway along its axial length. The second hole array comprises twelve equally sized holes, smaller than the holes of the first array, that penetrate the liner a predetermined distance aft of the first hole array. The holes of the second array are equiangularly distributed and each second hole is circumferentially aligned with a first hole. A third hole array penetrates the liner a predefined distance aft of the first array. The third holes are nonuniformly sized and nonequiangularly distributed to regulate the spatial temperature profile of combustion gases exiting the combustor can. The quantity, size, distribution and location of the holes mitigates undesirable exhaust emissions without affecting the performance or durability of the engine.

Abstract: A premixing, tangential entry fuel injector (10) for a gas turbine engine features a secondary fuel-air injection insert (40) positively secured to a centerbody shell (38) by a braze joint (98). A secondary fuel supply tube (42), positively secured to both a centerbody base (36) and to the insert (40), is curved in at least two dimensions. In an exemplary embodiment, the tube is coiled into a spiral shape covering a single 360.degree. cycle. During engine operation, the centerbody expands axially in response to elevated temperatures in the engine's interior, causing the insert (40) to be displaced away from the base (36). The curvature of the tube allows the tube to flex slightly to accommodate the displacement. Ideally the curvature of the tube is such that the tube's natural frequency is well above the maximum vibratory frequency that the tube will experience during engine operation.

Abstract: A premixing fuel injector for a turbine engine includes easily replaceable means for monitoring temperature or other conditions of interest in the interior of the injector. The fuel injector includes a guide conduit (70) that penetrates into the injector's interior and has an externally accessible opening (74) for receiving a sensor probe (88). The probe carries at least one sensor, such as a thermocouple junction (106), for monitoring temperature or other conditions inside the injector. In one embodiment, the guide conduit has a nonlinear shape and the probe shank (92) is sufficiently flexible to follow the contour of the conduit and sufficiently rigid to overcome any insertion resistance that the conduit might offer. The flexibility of the shank (92) may vary longitudinally to enhance insertability of the probe into the conduit.

Abstract: A bellcrank mechanism (52) for applications in which unequal transverse forces (F.sub.i, F.sub.o) act on the two legs of a bellcrank support clevis includes a bellcrank bracket (64), a bellcrank (54) having a support clevis (56), and a set of bearings (84a, 84b) having unequal load bearing areas (99a, 99b). The bearings are installed in apertures (80) in the support clevis and are axially clamped to the support bracket to pivotably and transversely support the bellcrank so that relative pivotal motion occurs at the interface (102a, 102b) between the exterior surface (99a, 99b) of each bearing and the perimeter surface (100a, 100b) of the corresponding clevis aperture (80). The bearing having the larger load bearing area is aligned with the larger transverse force and the bearing with the smaller load bearing area is aligned with the smaller transverse force to improve the durability and reliability of the bellcrank mechanism.

Abstract: The invention is a penetration resistant turbine engine fan casing (12) for containing separated fragments of a fan blade (16). The casing includes a penetration susceptible support case (14), a penetrable covering (32) circumscribing an impact zone (I) of the support case and an optional, but highly recommended collapsible support covering (34) circumscribing the case but axially offset from the impact zone. A containment covering (36) circumscribes both the penetrable covering (32) and the support covering (34). In a preferred embodiment, the coverings are aromatic polyamide fiber fabrics and the support covering is a collapsible cellular array. In operation, a detached fragment of a fan blade penetrates through the case (14) and the penetrable covering (32), and is plastically deformed by the penetrable covering to reduce the fragment's potential for damaging the containment covering (36).

Abstract: A hydrostatic bearing is uniquely configured for improved operability. A hydrostatic bearing (32) has a collar (42) that circumscribes a shaft (18) to define a fluid film annulus (50) for radially confining a load supportive fluid film. An array of pockets (52) distributed circumferentially along a bearing surface (48) communicate with vent regions (64a, 64b) in which the vent pressures are substantially unequal. Supply passages (76) associated with the pockets (52) are oriented at an angle .theta. for injecting fluid into the annulus with an axial directional component directed toward the higher pressure vent region. The orientation angle .theta. compensates for the propensity of the fluid to preferentially feed the low pressure side of the bearing. Further, a hydrostatic bearing (132) has a collar (142) that circumscribes a shaft (118) to define a fluid film annulus (150) for radially confining a load supportive fluid film.