Abstract: In a gas turbine engine, a method and apparatus for containing molten materials and ignited titanium and titanium alloys within the confines of the turbine engine environment. The method includes the step of first applying a bond coating to the inner surface of the outer compressor casing. The bond coating is then plasma oversprayed with a non-reactive, thermally insulative ceramic top coating. The apparatus includes a substrate having a bond coating and a ceramic top coating, surrounding at least a portion of the gas turbine engine, for containing turbine engine fires within the turbine engine environment. Preferably, the bond coating is a Ni--Co--Cr--Al--Y alloy, and the top coat is stabilized zirconia.

Abstract: A compressor for a gas turbine, comprises a rotor including a plurality of rotor parts, and blades for a plurality of stages, e.g., twelve stages, implanted in the rotor parts, the rotor part in which the blades for at least two of the stages are implanted is made of a Ni--Cr--Mo--V low alloy steel, and the Ni--Cr--Mo--V low alloy steel has substantially an entire bainite microstructure comprising, in weight percent, C of 0.15-0.40%, Si not more than 0.1%, Mn not more than 0.5%, Ni of 1.5-2.5%, Cr of 0.8-2.5%, Mo of 0.8-2.0%, V of 0.1-0.35% and the balance being substantially Fe. Blades for at least two of the stages are implanted in one of the rotor parts.

Abstract: An improved, lightweight, turbine housing unit for an intermittent combustion reciprocating internal combustion engine turbocharger is prepared from a lay-up or molding of carbon--carbon composite materials in a single-piece or two-piece process. When compared to conventional steel or cast iron, the use of carbon--carbon composite materials in a turbine housing unit reduces the overall weight of the engine and reduces the heat energy loss used in the turbocharging process. This reduction in heat energy loss and weight reduction provides for more efficient engine operation.

Abstract: The centrifugal pump includes a separable, multipartite impeller assembly and preferably incorporates a shock-absorbent shaft support that is tolerant of impeller vibrations or minor imbalances in the impeller assembly. The multipartite impeller assembly comprises an impeller portion, a wet-end magnetic coupler, and a radial bearing. The impeller portion and the wet-end magnetic coupler are secured together by a snap-fit joint, which is reinforced by a radial bearing adjacent to the snap-fit joint. The shaft support has an encapsulation junction which secures braces to a peripheral base.

Abstract: Casing assembly for a gas turbine engine comprising an annular cross section casing around which a plurality of layers of flexible material are wound. One or more rigid panels are positioned between the wound flexible material and the annular casing. The rigid panel provides enhanced containment of a detached fan blade or part of a fan blade by distributing the load of the detached blade across the wound flexible material.

Abstract: An ultra high head pumpturbine power generating plant with a turbine having a runner rotating with water flow supplied through a high head conducting tube. A rotary electric machine rotates with rotation of the runner. The head is in the range of 400-600 m, and the runner is at least 5 meters in diameter. The said runner has characteristics of toughness at room temperature: at least 500 N/mm.sup.2, or tensile strength at room temperature: at least 650 N/mm.sup.2, elongation at least 16%, reduction of area at least 45%, 2 mm U-notch impact value at 0.degree. C. at least 100 J, and fracture toughness at least 6000 N/mm.sup.3/2.

Abstract: An airfoil is provided having a cross-sectional geometry which includes a first wall, a second wall disposed opposite the first wall, a leading edge, a trailing edge disposed opposite the leading edge, and a first cavity. The first cavity is disposed between the first and second walls, and the leading and trailing edges. The cross-sectional geometry extends between a first and a second end, and the airfoil is formed from discontinuously reinforced aluminum.

Abstract: An earth and sand wear resisting hydraulic machine disposed in pressurized water and having movable guide vanes, has a wear resisting material against earth and sand applied by spraying or welding to the front end of a vane body of each guide vane, to the surface of a vane body portion located below the center of a water flowing portion of the vane body and to upper and lower end faces of the vane body. Consequently, the guide vanes and end faces are protected against wear caused by earth and sand.

Abstract: An air compressor with porous surfaces to separate particles from air flowing therethrough, using curvilinear flow paths to effect the same.

Abstract: A pump for pumping molten metal includes a motor supported by motor mounting structure above a bath of the molten metal. A shaft has one end connected to the motor. An impeller is connected to the other end of the shaft. The motor mounting structure supports the motor above a bath of molten metal. A device connects the motor to the base member, facilitating replacement of the shaft. The pump may be cleaned by rotating the shaft in a shaft sleeve, the impeller being disposed in an impeller chamber of a base. The rotational velocity of the shaft is adjusted to approximate the velocity at which cavitation occurs in the pump. Metal oxides inside the shaft sleeve are then removed from the pump.

Abstract: An electrically driven air pump has a housing incorporating an electric motor in one section of the housing and a pump mechanism coupled to the motor in another section of the housing. The housing has a pump cover enclosing the pump mechanism, made of plastic and having an end wall to which a metal reinforcement member is joined by injection molding. The metal reinforcement member is formed as a ring having inner and outer perimetral surfaces and a plurality of radial slots are formed in the ring for passage of the plastic material therethrough to anchor the reinforcement member to the end wall. The slots extend from the inner perimetral surface of the ring towards the outer perimetral surface but terminate before reaching the outer perimetral surface. The outer perimetral surface of the metal reinforcement member is free and unobstructed for undergoing dimensional change due to temperature variation.

Abstract: A double wall hot gas path part for turbines, such as an airfoil, combustor, duct or shroud, comprises an outer skin and an inner support wall that are metallurgically bonded to one another. The double wall contains integral channels for passage of cooling air adjacent to the skin. The skin may be a metal alloy skin or a microlaminate structure, including microlaminate composite structures. Microlaminate composites typically have a lower density than that of the material used for the support wall, and a simplified internal geometry, which promote weight reductions in the parts and increases in engine operating efficiency.

Abstract: A turbine engine vane segment, including spaced apart band or platform members and at least one airfoil member carried at metallic bonds between the platform members, is improved by providing at least one, but not necessarily all, of the segment members as an improved member having a directionally oriented Ni base superalloy microstructure with a stress rupture strength greater than the stress rupture strength of the balance of the segment members, which have a conventional generally equiaxed microstructure. For example, the balance of the members are conventionally cast from a Co base alloy. The coefficient of thermal expansion of the improved member is different from that of the balance of the members. A metallic bond including a brazed structure is provided between the improved member and the balance of the members, possessing strength sufficient to carry the stresses caused by differences in coefficients of thermal expansion of the dissimilar materials.

Abstract: An improved, lightweight, turbine housing unit for an intermittent combustion reciprocating internal combustion engine turbocharger is prepared from a lay-up or molding of carbon-carbon composite materials in a single-piece or two-piece process. When compared to conventional steel or cast iron, the use of carbon-carbon composite materials in a turbine housing unit reduces the overall weight of the engine and reduces the heat energy loss used in the turbocharging process. This reduction in heat energy loss and weight reduction provides for more efficient engine operation.

Abstract: An impeller for a molten metal pump having a cylindrical body comprised of a refractory material. The cylindrical body includes generally coplanar top and bottom surfaces. A central bore is provided in the top surface to provide a point for mating with a shaft. A plurality of circumferentially spaced passages extend from the top surface to a side wall of the impeller, each of the passages being separate and preferably having an inlet opening which is equal to or less than the corresponding outlet opening in size.

Abstract: A turbocharger for an internal combustion engine, for improving the turbocharger efficiency by manufacturing a compressor housing by a non-expensive method excellent in productivity, has a structure that a housing wall member located on an inner periphery of a compressor housing metal portion and facing to a curved profile portion of a compressor impeller is separately formed by, for example, PPS resin-forming, and integrally held and secured by a screw member engaging with a screw hole provided in the housing metal portion.

Abstract: Blades for use in combusion turbine engines are formed from a single crystal aluminum garnet body--desirably a rare earth aluminum garnet body--having an epitaxial surface layer of a second aluminum garnet having a lattice constant larger than that of the body garnet so as to provide a compressive strain, to thereby strengthen the blade.

Abstract: A high pressure centrifugal slurry pump in which the impellers and their associated diffusers are formed of hard chrome iron. A liquid-tight high pressure containment shell surrounds the impellers and diffusers and is radially spaced from them. The resulting space between the array of impellers and diffusers and the containment shell is in fluid communication with the interiors of the impellers and diffusers, preferably through a channel located between the last diffuser of the pump and the end wall at the high pressure end of the pumping chamber.

Abstract: A formed disc for use in a low pressure rotor has a rim made of a high alloy metal of between approximately 9% and 17% chromium. The rim can be annular in shape and slide onto the perimeter of an unformed disc for the two components to be fused together, thus fabricating a formed disc. Additionally, the rim can be split into a number of components and fused together on the perimeter of a rotor disc to form a complete rim. Further, an entire disc can be made out of the high alloy metal.

Abstract: A power generation gas turbine includes first stage turbine blades made of an alloy whose 10.sup.5 -hour 14-kgf/mm.sup.2 temperature capacity is 920.degree. C. or over, second and subsequent stage turbine blades made of an alloy whose 10.sup.5 -hour 14-kgf/mm.sup.2 temperature capacity is 800.degree. C. or over, first stage turbine nozzles made of an alloy whose 10.sup.5 -hour 6 kgf/mm.sup.2 temperature capacity is 900.degree. C. or over, and second and subsequent stage turbine nozzles made of an alloy whose 10.sup.5 -hour 6-kgf/mm.sup.2 temperature capacity is 800.degree. C. or over.

Abstract: In a method of investment casting a turbine nozzle which includes an outer band, an inner band and an airfoil section extending between the inner and outer bands, an improvement including shaping a temporary wax form, and external shell and internal core components used in casting such that during pouring of molten metal into a space created by removal of the wax form, shell material lies on opposite sides of an outer fillet connecting the outer band to the airfoil section. The resulting gas turbine nozzle includes first and second horizontally oriented ribs extending about interior peripheries of the airfoil section vertically adjacent the outer and inner band fillets.

Abstract: An aggregate for feeding fuel from a supply tank to an internal combustion engine of a motor vehicle has a feed pump having a disk-shaped feeding member, and means for forming a pump chamber in which the feeding member rotates, the means including a first wall part and a second wall part arranged at a distance from one another in direction of a rotary axis of the feeding member, at least one of the wall parts having a ring portion formed for a radial limiting and connectable with the other of the wall parts, the first and second wall parts and the feeding member which is preliminarily increase in volume are positioned relative to one another without a gap, and thereafter the first and second wall parts are fixedly connected with one another.

Abstract: For use in a compressor unit of gas turbine engine, a blade having a tip portion. An abrasive portion is formed on the tip portion with the abrasive portion comprising a dispersion of discrete particles of cubic boron nitride disposed on the tip portion. A shroud is coated with a porous ceramic abradable material based on preferably 8% yttria-stabilized zirconia. The abrasive portion of the tip portion contacts the abradable material. In the preferred embodiment, the abradable material is treated with boron nitride composited polyester that is burned out of the material via thermal exposure to thereby improve porosity within the abradable material.

Abstract: A stator vane assembly for a gas turbine engine that includes a plurality of circumferentially spaced ceramic vanes, each of which has an inner and outer ceramic shroud, and a ceramic post extending from one of the shrouds, and a metallic platform having a plurality of circumferentially spaced sleeves. A tolerance ring is mounted in each of the sleeves and then the ceramic posts are pressed into the rings. The assembly is then ready to be mounted within the engine. A method for assembling these components to form the stator assembly is also described.

Abstract: In order to create an adjusting ring for the synchronous alteration of the angle of pitch of guide vanes of a compressor having several bearing points for mounting on a compressor housing of the compressor, which can be manufactured at least partially from materials with a low coefficient of thermal expansion and is, nevertheless, compatible with a metallic compressor housing with respect to temperature, it is suggested that the adjusting ring comprise curved ring segments each arranged between two adjacent bearing points, the curvature of the ring segments decreasing during an increase in the temperature of the ring segments so that the bearing points between the ring segments are displaced outwards in a radial direction.

Abstract: A lightweight high temperature rotor blade attachment structure for use in a gas turbine engine. The lightweight high temperature rotor blade attachment lug being cast of a single crystal alloy and the lug is then bonded to a conventional nickel based wheel. A circular arc firtree is utilized to connect the insertable turbine blade between a pair of circumferentially spaced lugs that have been bonded to the turbine disk. In an alternate form of the present invention the attachment lug includes an internal cooling passage for receiving cooling fluid from a compressor. More particularly, the present invention discloses a single crystal attachment lug that is bonded to a powdered metal nickel alloy rotor disk and includes internal cooling passages, and in one form is designed for use with turbine blades that do not have a platform.

Abstract: Steam turbine fluid directing components are improved in erosive wear resistance by application of either relatively tougher and relatively less hard thermal spray or relatively harder and relatively less tough diffusion alloy surface modification to different portions of the component as a function of the locally greater or locally smaller angle of attack of solid particles on those portions in the use condition of the component.

Abstract: The present invention relates to a .gamma." strengthened nickel based alloy having an improved resistance to hydrogen embrittlement and to a process for forming the same. The nickel based alloy consists essentially of from about 0.02 to 0.06 wt % carbon, from about 11 to 13 wt % chromium, from about 17 to 19 wt % iron, from about 2.80 to 3.30 wt % molybdenum, from about 5.75 to about 6.25 wt % columbium+tantalum, from about 1.75 to 2.25 wt % titanium, from about 0.4 to 0.8 wt % aluminum and the balance essentially nickel and is in single crystal form. The nickel based alloy of the present invention has particular utility in high pressure hydrogen environments such as rocket engine components.

Abstract: In a pump for pumping molten metal including a motor and a shaft connected at an upper end to the motor and at a lower end to an impeller which is rotatable in a molten metal bath, the improvement being an apparatus for impeding oxidation of the shaft, including a gas source for releasing gas and a gas feed tube in fluid communication with the gas source, the gas feed tube being positioned to direct gas along the outer surface of the shaft.

Abstract: An airfoil blade, such as a jet engine turbine rotor blade. An internal serpentine coolant circuit has a last downstream passageway bounded by four monolithic inner walls which are monolithic with at least a portion of the outer walls. Two of the inner walls are spaced from the outer walls and contain air impingement orifices creating two impingement chambers. Some coolant in the serpentine circuit exits the airfoil blade through a coolant exit in the blade tip. The remaining coolant in the circuit passes through the impingement orifices and exits the blade through film cooling holes in the outer walls.

Abstract: A torque converter stator made by injection molding of plastic material includes a metallic one-way clutch outer race which is insert molded within the stator hub. A plurality of recesses forming lubricant passages extend through the wall of a radial flange of the hub. The lubrication recess (30) is defined by a part-cylindrical outer wall (32) and a pair of planar side walls (34) spaced apart by a distance d. The juncture of the outer wall (32) and the side wall (34) is filleted to form a rounded corner (36) having a radius of curvature R1. To relieve the weld line (60) from concentration of residual stress due to post-molding shrinkage while avoiding stress concentration at the rounded corners (36), the ratio R1/d is selected to be 0.18-0.35.

Abstract: The present invention relates to a steam turbine comprising a rotor shaft integrating high and low pressure portions provided with blades at the final stage thereof having a length not less than 30 inches, wherein a steam temperature at first stage blades is 530.degree. C., a ratio (L/D) of a length (L) defined between bearings of the rotor shaft to a diameter (D) measured between the terminal ends of final stage blades is 1.4 to 2.3. This rotor shaft is composed of heat resisting steel containing by weight 0.15 to 0.4 % C, not more than 0.1 % Si, 0.05 to 0.25 % Mn, 1.5 to 2.5 % Ni, 0.8 to 2.5 % Cr, 0.8 to 2.5 % Mo and 0.15 to 0.35 % V and, further, the heat resisting steel may contain at least one of Nb, Ta, W, Ti, Al, Zr, B, Ca, and rare earth elements.

Abstract: Run-on linings for turbo-engines are arranged between the free ends of moving blades and a housing of a compressor or a turbine of a turbo-engine. The run-on linings are formed of a carrier and fiber bundles and are fastened on the circumference of the housing.

Abstract: The composite vane is moulded by injecting resin into a preform of layers of reinforcing fibres according to the RTM method. The skins of its main vane section as well as of its root and tip via which it is connected to the flow-straightener central body and to part of the duct are laminated with a pile of at least three layers of reinforcing fibres, and complementary piles at the root and tip exhibit at least one fastening tab. The central body is made of metal or composite and the composite vanes are interchangeable, or the vanes and the central body are injection-moulded as a single piece using the RTM method.

Abstract: Stator vanes located between compressor stages in a gas turbine engine are fabricated with a composite outer shell made of graphite fibers in an epoxy binder that is laid-up over a core of felt-like material selected to have an elongation velocity that is greater than the elongation velocity of the shell.

Abstract: High toughness stainless steel type 13Cr5Ni containing C: 0.008-0.03% (by weight, all of the following elements), Si: max. 1%, Mn: max. 2%, Cr: 10.0-14.0%, Ni: 4.0-7.0%, and Mo: 0.2-2.0%, in which (Cr/Ni) ratio is in a range of 2.0-3.0 or (C/Mo) ratio is in a range of 0.015-0.1, as a structural material for fluid machinery, austenitic stainless steel containing C: 0.10-0.30% (by weight, all of the following elements), Si: max. 1%, Mn: max. 2%, Cr: 16.00-23.00%, Ni: 1.00-8.00%, and Co: 2.00-9.00%, and Ni+Co: 6.00-12.00% as a weld padding layer forming material, and fluid machinery using the same.

Abstract: In a non-metallic pump for pumping molten metal including a shaft, a motor at one end of the shaft, an impeller at the other end of the shaft, and a base having a chamber in which the impeller is rotatable, the improvement being a dynamically balanced impeller comprising a cylindrical center hub and five vanes extending outwardly from the hub, wherein the vanes are equally spaced around the periphery of the hub.

Abstract: A molten metal pump having an elongated shaft with an impeller disposed adjacent the end of the shaft and a means for rotating the shaft. The impeller is formed with an imperforate substantially circular base surrounded by a bearing and has a surface facing toward the shaft. At least two imperforate vanes are connected to and extend substantially perpendicular from the surface and radially from the shaft or a hub securing the shaft toward a peripheral portion of the base. The vanes are spaced apart at terminal inlet ends along their entire radial dimension to create an inlet area comprised of the axial opening between adjacent vanes at the terminal ends and an outlet area comprised of a radial opening between adjacent vanes along the axial direction of the vanes. Each vane has a leading edge with a distal portion adjacent the periphery of the base portion which forms an angle of less than about 100.degree. relative to a tangent to said circular base drawn at the center of the vane.

Abstract: A wide gap braze repair, particularly for a gas turbine engine vane or a component in the hot section of the engine. The repair is characterized by a braze filled void in a damaged area of the component, a laser shock peened surface over the repaired area of the braze filled void, and a region of deep compressive residual stresses imparted by laser shock peening (LSP) extending from the laser shock peened surface into the repair.

Abstract: A magnetic pump is provided which is especially useful for pumping corrosive agents, having simplified components made of a hard ceramic, preferably silicon carbide, which form ceramic-on-ceramic axial and radial bearing surfaces. The pump has an impeller and magnetic rotor, each being mounted on an opposite end of a ceramic shaft by a respective ceramic bush. The shaft rides in ceramic first and second plain bearing bushes, each of which forms a radial bearing surface and an axial bearing journal end face. The ceramic impeller bush is secured to the shaft by a form fit and provides an axial bearing surface against the first bearing bush end face. Similarly, the ceramic rotor bush is secured to the shaft by a form fit and forms an axial bearing surface against the end face of the second plain bush.

Abstract: Blades for use in combusion turbine engine are formed from a single crystal garnet body--suitably an aluminum garnet, desirably a rare earth aluminum garnet--having an epitaxial surface layer of a second garnet having a lattice constant larger than that of the body garnet so as a compressive strain, to thereby strengthen the blade.

Abstract: Gas turbine engine static component with a metallic panel section, either linear or curved, that is susceptible to cracks initiated by features on the component has an elongated laser shock peened region having deep compressive residual stresses imparted by laser shock peening (LSP) disposed between the feature and a portion of the panel section, which is to be protected from failure, such that the laser shock peened region diverts cracks that propagate from the feature away from the portion of the panel section. The laser shock peened region preferably extends through the component and is may be formed by simultaneously laser shock peening first and second laser shock peened surface areas to form the laser shock peened region.

Abstract: A unitary composite stator vane for a gas turbine engine comprising an aerodynamically configured airfoil section, a foot extending substantially perpendicularly from one end of the airfoil section, and a smoothly contoured transition section interconnecting the airfoil section with the foot. The stator vane is comprised of a composite material including a plurality of compression molded, heat cured plies. The plies include a plurality of centrally located internal plies of reinforcement material of continuous yarns of para-aramid fibers. On each side of the internal plies are plies of resin impregnated graphite fiber material. The graphite fibers are protected by an external steel wire mesh ply covering the leading edges of the vanes. Substantially all of the internal para-aramid reinforcement fibers are discontinuous proximate the transition section between the airfoil section and foot.

Abstract: A thermal load relief ring is disposed between the mating surfaces of adjacent cases of a gas turbine engine and secured thereto by a dowel pin or bolt to assure the concentricity of the cases. The bolt and dowel pin are configured to assure the concentric fit of the components. These configurations allow the cases to be fabricated from different materials to allow a lighter and less expensive case.

Abstract: A fuel pump for supplying diesel fuel to an engine includes a pump housing, a motor mounted within the housing, a shaft extending from the motor, an impeller slidably attached to the shaft which has a prime number of vanes spaced unevenly about its circumference, a chamber body, and a chamber cover with a bleed orifice. The chamber body and cover form a chamber for the impeller and are held together by the housing. The chamber body and cover have pump channels of constant depth and are made of phenolic with fiberglass fill. The impeller is made of phenolic with fiberglass fill and granular fill.

Abstract: A turbocharger includes a turbine and compressor housing attached by a circumferential clamp with circumferentially staggered contact points between the clamp and the housings to reduce heat transfer from the turbine housing to the compressor housing. The mass of the turbine housing is reduced and the mass of the compressor housing is increased to reduce the transfer of heat from the turbine housing to the compressor housing from the thermal flux of the turbine side heat energy. The compressor housing mass is increased by incorporating a heat-transfer interface between the compressor housing and the oil reservoir cover, which oil reservoir extends circumferentially around the axis of the turbocharger rotor shaft. Concentricity between the components of the turbocharger is achieved by creating the radial junction between the turbine and compressor backwalls on the smallest feasible diameter to minimize the effects of thermally induced distortion on component concentricity.

Abstract: A composite stator vane for a gas turbine engine comprising a plurality of compression molded, heat cured plies, the plies including a plurality of centrally located internal plies of reinforcement material of unidirectional yarns of para-aramid fibers, a plurality of plies of resin impregnated graphite fiber material on each side of the centrally located plies of reinforcement material, and an external steel wire mesh ply on the leading edge of the vane.

Abstract: This invention relates to a single crystal casting to be used under high stress, high temperature conditions up to about 2030.degree. F., characterized by an increased resistance to creep under such conditions. The casting is made from a nickel-based superalloy consisting essentially of the following elements in percent by weight: from 6.2 to 6.8 percent rhenium, from 1.8 to 2.5 percent chromium, from 1.5 to 2.5 percent cobalt, from 8 to 9 percent tantalum, from 3.5 to 6 percent tungsten, from 5.5 to 6.1 percent aluminum, from 0.1 to 0.5 percent titanium, from 0.01 to 0.1 percent columbium, from 0.25 to 0.60 percent molybdenum, from 0 to 0.05 percent hafnium, from 0 to 0.04 percent carbon, from 0 to 0.01 percent boron, from 0 to 0.01 percent yttrium, from 0 to 0.01 percent cerium, from 0 to 0.01 percent lanthanum, from 0 to 0.04 percent manganese, from 0 to 0.05 percent silicon, form 0 to 0.01 percent zirconium, from 0 to 0.001 percent sulfur, from 0 to 0.

Abstract: The present invention relates to a steam turbine comprising a rotor shaft integrating high and low pressure portions provided with blades at the final stage thereof having a length not less than 30 inches, wherein a steam temperature at first stage blades is 530.degree. C., a ratio (L/D) of a length (L) defined between bearings of the rotor shaft to a diameter (D) measured between the terminal ends of final stage blades is 1.4 to 2.3. This rotor shaft is composed of heat resisting steel containing by weight 0.15 to 0.4% C, not more than 0.1% Si, 0.05 to 0.25% Mn, 1.5 to 2.5% Ni, 0.8 to 2.5% Cr, 0.8 to 2.5% Mo and 0.15 to 0.35% V and, further, the heat resisting steel may contain at least one of Nb, Ta, W, Ti, Al, Zr, B, Ca, and rare earth elements.

Abstract: Disclosed is an air motor having an engine pack (with a rotor provided with front and rear retainers, a stator, and vanes) which can be assembled and replaced even by an unskilled person. An air supply joint is engaged with guide projections formed on the inner peripheral surface of a housing, with its forward end portion held in contact with the rear retainer; the forward end portion being fastened by a nut member which is threadedly engaged with the housing. On the rear face of the forward end portion are formed a plurality of first projections produced of a rigid synthetic resin, and on the front face of the nut member corresponding to the first projection are formed a plurality of second projections, so that a firm relation of engagement is established by an elastic force of restoration of the first projection; that is, the nut member will not accidentally become loose owing to the locking effect of the first and second projections.