Abstract: A frame for a gas turbine engine is provided comprising a central hub having a circumferentially extending flowpath surface enclosing an interior cavity and an annular outer casing connected to the hub by a plurality of struts extending radially from the hub to the casing, wherein the flowpath surface has a plurality of inlets disposed in flow communication with the interior cavity and a plurality of outlets disposed in flow communication with the interior cavity. A flowpath member for a turbine frame hub is also provided having a plurality of inlets and outlets formed therein.

Abstract: A method for installing an expandable stiffener includes providing an assembly including a first sidewall and a second sidewall connected at a leading and trailing edge such that a cavity is defined therebetween, forming an opening extending through the first sidewall and the second sidewall, inserting a first expandable sleeve through the assembly opening such that the sleeve extends between the first and second strut sidewalls, and coupling the sleeve to the first and second sidewalls.

Abstract: A heat shield for a gas turbine engine hub which facilitates reducing thermal stress in an exhaust frame of a gas turbine engine. The exhaust frame includes the hub mounted within the engine with a plurality of supports. The supports extend radially outward from the hub through a primary flow cavity and facilitate flow to a secondary flow cavity. The heat shield defines the secondary flow cavity such that the secondary flow cavity is radially inward and axially adjacent the hub. The heat shield includes a plurality of thermal stress relieving corrugations.

Abstract: A water, pump includes a driven portion, a shaft connected to the driven portion, an impeller connected to the shaft, and a body supporting the driven portion for relative rotation therewith. The water pump is characterized in that the driven portion and the shaft are formed integrally by resin molding, and an outer surface of the bearing is fixed to the driven portion.

Abstract: An annular turbine frame has ring disposed coaxially about an axial centerline axis and includes a plurality of circumferentially spaced apart ports. A plurality of circumferentially spaced apart struts are joined radially to the ring by devises on the ring. Each strut has radially opposite first and second ends, and a through channel extending therebetween. Each of the channels is aligned with a corresponding one of the ports. Each of the ports has a port counterbore though a radially outer portion of the port forming a shoulder in the port. A seal is disposed within the port counterbore between the shoulder and the strut.

Abstract: A low pressure fuel system for a gaseous fuel internal combustion engine in which the source of gaseous fuel is at a pressure lower than the intake manifold pressure of the internal combustion engine. The gaseous fuel is inducted into the interstage duct of a multi-compressor combustion air turbocharger associated with the internal combustion engine. The combined flow of air and gaseous fuel is further compressed in the second compressor stage of the turbocharger.

Abstract: An annular turbine frame includes a first ring such as a radially outer casing disposed coaxially about an axial centerline axis and having a plurality of circumferentially spaced apart first ports. A plurality of circumferentially spaced apart hollow struts are joined radially to the first ring by a corresponding plurality of collars. Each strut has radially opposite first and second ends, and a through channel extending therebetween. Each of the collars is disposed between a respective one of the strut first ends and the first ring in alignment with a respective one of the first ports for removably joining the struts to the first ring. Each of the collars includes a base disposed against the first ring and has a plurality of mounting holes for receiving mounting bolts therethrough to removably join the base to the first ring. The base has a central aperture aligned with the first port. Each collar mounting hole has a hole counterbore through a radially outer portion of the collar mounting hole.

Abstract: A flow metering turbine comprises a tubular body through which flows the fluid to be measured. The tubular body houses an upstream spider and a downstream spider each formed by a hub and fixed vanes, bearing the hub in the tubular body. The mutually facing ends of the hubs have a cavity on the axis of the tubular body for receiving a support bearing and thrust bearing. A screw member formed by a hub bearing vanes and a shaft is located between the spiders, the ends of the shaft being located in the support bearings of the spiders and against the thrust bearings. At least one fluid duct runs through each spider, opening into the cavity in line with the support bearing and thrust bearing.

Abstract: A bearing gallery thermal movement isolation device permits the inner bearing support ring of the bearing gallery to float freely relative to the outer bearing gallery housing under thermal expansion and contraction during engine operation without transmitting thermally induced movement or forces to the oil supply and scavenge lines, or to the cooling air supply line. An oil transfer tube isolation connector is disposed on an inward end of the transfer tube and on the bearing gallery. The connector includes a radially extending sleeve on the inner bearing support ring; and a sliding O-ring engaging the sleeve and transfer tube. An oil scavenge canal is defined between the O-ring and a threaded connection between the transfer tube and the oil supply boss of the bearing gallery.

Abstract: An annular support for supporting radial bearings and accommodating radial expansion and lateral displacement, and damping vibration of the bearing with respect to a static support structure includes an annular casing to support a bearing therein and a cantilevered support which has a first and second rings, axially spaced apart and connected by a plurality of flexible beams. The first ring is connected to the annular casing which is spaced radially, inwardly from the cantilevered support and the second ring is connected to the static support structure so that the flexibility of the beams permits the annular casing to move laterally in small distance while the annular support is supported to the static support structure. The flexibility is adjusted by selection of a combination of number, width and thickness of the beams. A service line is able to have an access between two adjacent beams to the annular casing to provide lubricating fluids.

Abstract: A structural member is provided for an exhaust-gas connection of a turbomachine, in particular a steam turbine, and a turbomachine bearing disposed in the exhaust-gas connection. The structural member is cast in one piece and has a connection part and/or a bearing part for accommodating the bearing as well as a supporting arm configuration with at least one supporting arm. A pipe conduit which is cast into the structural member leads through a connection part, a supporting arm and a bearing part. A set of at least two such structural members form an exhaust-gas connection and a frame for the bearing of the turbomachine.

Abstract: A stator apparatus for mounting upstream of an intake to a rotating machine which blows pressurized air, or other media, from discharge orifices at a pressure and velocity to minimize velocity defects or turbulence in the wake of the stator prior to the plane of rotation of a rotating member of the machine. The rotating member then encounters a substantially uniform velocity medium at the plane of incidence, which substantially reduces uneven loading on the rotating member, thereby reducing noise and reducing high-cycle failure of that rotating element. The distribution and size of the orifices is determinable by placing the stator apparatus in a wind tunnel, or on the intake of a apparatus simulating the intake of the rotating machine, measuring the turbulence or velocity defects in the stator wake, and modifying the distribution and size of the orifices until the turbulence is minimized.

Abstract: An open bowl for a vertical turbine pump, includes a bowl body having an inner wall and an outer wall, both walls being of substantially constant optimum thickness, surrounding a vertical axis and connected by diffuser vanes which define hydraulically optimized diffuser passages through the bowl body extending from a bottom end to a top end, the diffuser vanes being radially hollow and providing open paths through the inner and outer walls to a cavity surrounded by the inner wall; a flange at the top end of the outer wall for attachment of a discharge conduit for the pumped fluid; provision on the bottom end of the outer wall for attaching to a flange of a suction bell; further provision on an inner surface at the top of the inner wall for providing sealing engagement with an upper end of a separable substantially cylindrical bearing housing; and provision at the bottom end of the inner wall for attaching to a flange of the bearing housing.

Abstract: A bearing support structure for a gas turbine engine comprises an annular array of stator vanes and a radially inner bearing support portion which are interconnected by an annular array of radially extending U-shaped cross-section parts. The U-shaped cross-section parts are interconnected at their radially outer extents and are arranged so that adjacent parts are open in generally opposite axial directions. Such a bearing support structure can carry service pipes with good accessibility and be produced by casting, thereby reducing its cost.

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: In a conduit constituting the outlet from turbo machinery such as a turbine or compressor, stall gas having high static pressure and low velocity is collected. This stall gas is then routed through struts--preferably teardrop shaped--to more central low static pressure and high velocity gas flow areas. At these areas, the gas is discharged, preferably through multiple manifold openings. Mixing of the collected high static pressure, low velocity stall gas with the low static pressure, high velocity main stream gas occurs. Turbine noise, vibration, and back pressure are decreased with resulting improvements of efficiency. Variations are illustrated including adaptation of gas flow transfer utilizing turning vanes, fairings, rectangular duct turns, and struts for placement in turbine turbo machine outlets having high turbulence or variable swirl.

Abstract: A fan unit for a building's air handling system comprising a support structure including a front wall with an air inlet opening formed therein and a bladed fan wheel rotatably mounted on the support structure about its central axis and having an axial air intake on a front side thereof confronting the inlet opening. The fan wheel has an annular air outlet extending about its circumference. A fixed centerbody directs air flow into and within the fan wheel and extends along the central axis from a relatively narrow front end located in the air inlet opening to a wider rear end located within the fan wheel. This centerbody has an annular exterior surface which curves outwardly in a section thereof adjacent the wider rear end. The centerbody extends through the axial air intake of the fan wheel. Support struts rigidly support the centerbody in a fixed position. Preferably the centerbody is filled with sound attenuating material.

Abstract: A low profile joint is provided for a strut tube extending radially through a strut extending between an outer casing and an inner hub in a gas turbine engine frame. The strut tube has a longitudinal axis and a closed distal end. A sideseat is spaced from the distal end and is disposed substantially perpendicularly to the longitudinal axis to define a flow orifice. A secondary tube has a ballnose at a distal end thereof disposed in abutting contact with the sideseat for channeling fluid therebetween. A fastener joins together the strut and secondary tubes in compression between the ballnose and sideseat to maintain sealed contact therebetween for channeling fluid between the strut and secondary tubes.

Abstract: The arrangement of a gas turbine engine suitable for high bypass ratio aircraft engines in which gases circulate in a primary air channel (7) and a secondary channel (8) concentric to said primary air channel, is characterized in that structural vanes (22) connecting the channel delimitation casings (2, 10, 14, 5) with each other, alternate with aerodynamic vanes (20) for guiding the gases on a common circumference of the engine bypass air channel (8), and in that the structural channels branch out between the two channels. The resulting advantages are simplicity of construction associated with a reduction in the space required for housing the channels and good resistance without notable increase of the total mass.

Abstract: A floating interturbine duct assembly for a high temperature power turbine, including means for automatically adjusting to accept thermal expansion movement between dissimilar materials.

Abstract: A seal is provided between an inner flowpath and inner band of a turbine frame for confining cooling air channeled therebetween. The seal includes a frustoconical seal support and a radially outer seal ring integrally joined to a smaller diameter distal end of the support. A radially inner ring is fixedly joined to the inner band coaxially with the outer ring and is spaced radially inwardly thereof to define a gap therebetween sized for limiting leakage of cooling air from a chamber defined between the seal and inner flowpath.

Abstract: A centrifugal pump comprises a pump housing having a flange connected thereto. An inlet housing has an inlet opening. The inlet housing is connected to the flange remote from the inlet opening. The inlet housing includes an inlet funnel. The inlet funnel has a perforated sidewall. The inlet funnel extends from adjacent to the flange to adjacent to the inlet opening.

Abstract: An exhaust housing having an eductor is provided. The eductor includes an outer annular casing circumscribing an inner annular casing to define a flow path therebetween for receiving the exhaust gas from the turbine section of an engine. A plurality of struts are integral with both casings. The struts have passages that extend from the exterior of the outer casing to the interior of the inner casing. A non-oil lubricated bearing is mounted within the interior of the inner casing for journaling a rotating shaft. During operation, the kinetic energy of the high velocity exhaust gas flowing between the casings and into a tailpipe induces cooling airflow from the exterior of the exhaust section, through the passages, across the bearing, and then out to the tailpipe.

Abstract: In an axial flow gas turbine, the outlet blading followed by an exhaust casing (5) whose boundary walls essentially comprise a ring-shaped inner part (6) at the hub and a ring-shaped outer part (7) which delimit a diffusor (9). The outlet-end bearing arrangement (4, 11) of the turbomachine is arranged in the hollow space within the inner part. The bearing casing (11) can be repositioned by adjustment elements (12) arranged on the inner part (6) of the exhaust casing and is supported on the foundation via at least one sprung support (15).

Abstract: A turbine casing includes circumferential walls delimiting an annular stream for the flow of gases. The radial arms traversing the stream are completed by a channeling part on the downstream side which is bolted to the arms. The walls are formed of butt-joined tiles assembled together and joined to collars situated on the arms and the channeling parts by riveted ridge tiles. The invention results in a reduction of resistance to the flow of gases, as well as absorption without the production of excessive stresses of the original thermic dilations in the walls.

Abstract: A rotary fluid machine suitable for transferring energy between a fluid and a rotor assembly is disclosed. The rotor assembly contains a shaft carrying one or more impellers which are located between axially spaced radial bearings in a beam-type arrangement. The rotary fluid machine is of the beam type--i.e. it has one end of the shaft extending beyond one end wall of the housing and one end of the shaft terminating within the housing. Two passages are formed in the housing to allow fluid to flow in and out of the machine. One passage is formed in the housing parallel to and coaxial with the rotational axis of the rotor assembly. Fluid moving between the passage parallel to and coaxial with the rotational axis does not have to be redirected thus reducing fluid turbulence and improving machine efficiency.

Abstract: A turbine frame includes first and second coaxially disposed rings having a plurality of circumferentially spaced apart struts extending therebetween. A plurality of clevises join respective first ends of the struts to the first ring for removably joining the struts thereto. Each of the clevises includes a base removably fixedly joined to the first ring, and a pair of legs extending away from the base and spaced apart to define a U-shaped clevis slot receiving the strut first end. The first strut end is removably fixedly joined to the clevis legs by a pair of expansion bolts. The clevis base includes a central aperture aligned with a first port in the first ring for providing access therethrough. And, the strut first end abuts the first ring for carrying compressive loads therebetween and providing a seal therewith.

Abstract: A turbine frame includes first and second coaxially disposed rings having a plurality of circumferentially spaced apart struts extending therebetween. A plurality of clevises join respective first ends of the struts to the first ring for removably joining the struts thereto. Each of the clevises includes a base removably fixedly joined to the first ring, and a pair of legs extending away from the base and spaced apart to define a U-shaped clevis slot receiving the strut first end. The strut first end is removably fixedly joined to the clevis legs by a pair of expansion bolts. The clevis base includes a central aperture aligned with a first port in the first ring for providing access therethrough.

Abstract: An annular support (22) accommodates differential thermal growth between first and second support rings (24, 26). The support (22) prevents relative axial, circumferential lateral and bending movement between the rings (24, 26), while allowing uniform differential radial expansion and contraction.

Abstract: An axial flow turbomachine's engine core (16) and radially outwardly disposed fan case (18) are joined together with a radially extending segmented fan case strut (10). The strut (10) is segmented into a radially inner portion (20) and a radially outer portion (20) at a midspanly disposed strut joint (14). The strut joint (14) has an axially extending tapered tongue (26) which slidably engages with a mating axially extending groove (46). A radially extending flange (36) disposed proximate to the trailing edge (35) of the inner portion (20) is bolted to the radially extending flange (56) disposed proximate to the trailing edge (55) of the outward portion (40) when the tongue (26) is fully engaged with the groove (46) to releasably secure the strut joint (14). Another embodiment shows a pair of interlocked axially extending channels (60) each having a U-shaped cross-section replacing the interlocked tongue and groove (26,46) of the first embodiment.

Abstract: A gas turbine engine incorporates a bearing support assembly which mounts an inner annular bearing arrangement in radially spaced relation inwardly from a stationary outer casing. The bearing arrangement, in turn, mounts a turbine rotor within the outer casing for rotation about a central axis relative to the outer casing. A row of stationary stator vanes are fixedly attached to an extend radially inwardly from the outer casing toward the central axis.

Abstract: A turbine support for reacting structural loads from a rotor bearing cage to a case of a gas turbine engine. The turbine support includes a homogeneous main casting and a rotor bearing cage. The main casting has concentrically arranged inner, intermediate and outer walls. The bearing cage is radially inboard and a rigid appendage of the inner wall. The inner and intermediate walls define therebetween a longitudinal segment of the annular hot gas flow path of the engine. The outer wall is bolted to the engine case. The inner wall is connected to the intermediate wall by a plurality of generally radially oriented, angularly separated inner load bearing struts of the main casting. The outer wall is connected to the intermediate wall by a plurality of radially oriented, angularly separated outer load bearing struts of the main casting.

Abstract: An improved lightweight frame for gas turbine engine is disclosed. The frame includes a hub and a radially spaced casing with two rows of circumferentially spaced tie rods extending between the hub and the casing. In a preferred embodiment, jam nuts are provided on the tie rods for accommodating compressive loads therein. The tie rods are pretensioned so that during operation in a gas turbine engine, for example, wherein the tie rods are heated by combustion gases, thermal expansion of the tie rods and resulting compressive stress will be accommodated by the pretension so that in a preferred embodiment the tie rods may operate nearly stress free at normal operation. The two rows of tie rods and jam nut pairs allow the frame to accommodate effectively blade-out loads channeled to the frame 30.

Abstract: A turbine assembly includes an annular fairing and strut subassembly which provides mechanical strength to the turbine assembly and support for the rotor aft bearing. A readily demountable annular outlet guide vane assembly is mounted to the aft of the fairing and strut assembly for deswirling the exhaust gasses which exit the turbine assembly. The aft mounting of the outlet guide vanes allows for an axially shorter and lighter turbine engine design which removes greater inlet swirl than prior designs, with equal or less pressure loss.

Abstract: A lightweight rigid turbine engine frame incorporates a one piece annular cast outer casing formed with a circumferential polygonal reinforcing section. The outer casing is separated and spaced from an inner ring by a plurality of radially extending spacer struts. The spacer struts are clamped in compression between the inner ring and outer casing by tensioning members such as bolts. A thermally free floating heat shield is mounted to the bolts in a manner which minimizes thermal stresses by avoiding all undesirable constraint of the heat shield by the engine frame.

Abstract: The support structure for the bearing compartment for a gas turbine engine includes eight radial tie bolts connected with the clevis wherein the outer diameter clevis is connected to the mount ring with an accessible bolt for easy assembly and disassembly. The tie bolts, while preloaded in tension, can accept compressive loads during severe loading operation conditions. The turbine exhaust case housing the tie bolts and bearing compartment are designed to facilitate cooling and maintainability at reduced costs.

Abstract: A resilient shaft mounting for a pump includes one or more sets of leaf plates bearing inwardly from an inner surface of a tube and pressing a resilient bushing on a rotatable shaft. Three plates can each be disposed by their ends to press inwardly against a bushing formed by a water lubricated rubber tube operating as an anti-frictional contact element. The plates are larger than the internal diameter of the tube, and are welded together at their ends. Upon placing the plates in the tube, the plates deform inwardly against the tube to accomplish a tight yet resilient mounting.

Abstract: A bypass turbofan jet engine subassembly. A row of structural fan stators and a row of structural compressor guide vanes have their outer ends attached to the engine outer duct. The structural stator inner ends are attached by an inner support cone to the outer race of the fan rolling element bearing and the structural guide vane inner ends are attached by another inner support cone to the outer race of the compressor rolling element bearing. The fan and compressor outer races are interconnected by a tie bar. The subassembly eliminates the engine fan and compressor frames.

Abstract: An annular fairing forming a bolt guard associated with the heads of screws of an attachment carries, inside thereof and in line with each screw, first cylindrical sockets each of which comprises notch-shaped cut-outs at its inner end which cooperate with a pair of first lugs formed at the end of a respective second socket disposed within the first socket and further comprising a pair of inwardly curved second lugs cooperating with the head of the screw in such a way as to prervent rotation of the screw.

Abstract: A stator assembly for a gas turbine engine having a support structure and a stiffening ring 46 extending about the support structure 34 is disclosed. Various construction details which increase the rigidity of the support structure and enable the stiffening ring to accept axial and radial loads are developed. In one embodiment the stiffening ring 46 is the seal ring 52 for a seal end 74. In one particular embodiment, the thermal expansion characteristic of the support structure is greater than the thermal expansion characteristic of the stiffening ring to insure that the stiffening ring is in tension under normal operative conditions of the engine.

Abstract: A band clamp apparatus having two 180.degree. segments which are bolted together at flanges on the horizontal centerline. A substantial portion of each segment has a scalloped band contour for weight reduction. An internal groove in the band clamp which has parallel facing walls which engage the mated flanges of the casings of the engine/exhaust system. Local radial restraints are provided on the engine/exhaust system casings to achieve radial constraint and circumferential positioning of the band clamp apparatus.

Abstract: An improved structural strut for use in the fan section of a high bypass ratio gas turbine engine is described. The strut includes two I-beam shaped structural supports which are substantially perpendicular to each other, and extend along the major and minor axes of the strut, from the strut base to the strut tip. Face sheets, preferably made of composite material, are attached to both of the I-beam supports for acoustic damping effects.

Abstract: A fairing for mounting onto a gas turbine frame to isolate the frame from the hot gases passing the flowpath. The fairing includes mating forward and aft annular sections with each section having an outer wall and an inner wall defining the flowpath therebetween. A plurality of circumferentially-spaced hollow fairing struts radially extends between the inner and outer walls. The two sections are manufactured such that there are no misalignments or steps between the lineup of the two sections. The sections are placed over the frame struts and are coupled together.

Abstract: A flow meter includes a flow channel having walls and defining a direction of flow. Stators are provided, having walls, disposed at least partially within the flow channel. A rotor is included for rotating with respect to the stator. A one piece retainer is provided for assisting in limiting axial rotor movement comprising a first pair of spaced apart wall portions for engaging the flow channel walls wherein each wall portion in the first pair of wall portions is located on a side of an axis opposite from the other. A second wall portion is located on the axis for engaging the stator wall wherein compression of each of the first pair of wall portions toward the axis results in a component of force being applied to the second wall portion along the axis.

Abstract: This invention relates to a channel for supplying water to a vertical-axis Kaplan water turbine, wherein the vertical side walls thereof are oriented in convergent manner in order that, at turbine level, they join an end face of rounded form, of which the radius of curvature is slightly greater than the radius of the guide blades located above the turbine and the sleeve of the turbine shaft and/or an inclined fixed wall downstream of the turbine are provided, for preventing the development of suction eddies downstream of the sleeve of the turbine shaft.

Abstract: A supporting structure comprises a shell and a plurality of support members which are independent of each other, inserted in the shell and arranged so that the flexural rigidity is smaller in the water flow than in a perpendecular to the water flow. The supporting structure supports one place of an axial-flow bulb turbine which is to be supported at two places spaced in the water flow direction from each other. The support structure is more flexible in the water flow direction than in the perpendicular direction to the water flow, so that small bending stresses are induced in the support structure and the axial stresses induced in the support structure by the weight and the buoyancy acting on the turbine and the bending stresses induced in the support structure by axial deformation of the turbine are kept below an allowable stress of material constituting the support structure.

Abstract: A pump having a main shaft which is rotatably supported in a support housing via support bearings. The support bearings are provided with passages which are connected via discharge openings with the space around the pump. As a result, no pressure can build up between the support bearings and a bearing disposed at the lower end of the shaft. Medium which during operation of the pump gets by the seals and the support bearings can flow off out of the pump through these passages and the discharge openings.

Abstract: A turbine flowmeter comprises a flowmeter housing through which a fluid to be measured flows, a turbine rotor rotatably provided within the flowmeter housing and comprising a rotor hub and a plurality of blades which are unitarily provided to the rotor hub, a bearing mechanism for mechanically supporting the rotor hub in a rotatable manner by making mechanical contact with the rotor hub, a stationary member which is provided in the flowmeter housing in an opposing manner to the rotor hub, and a dynamic pressure bearing part for to building up a dynamic pressure bearing by the fluid between the rotor hub and the stationary member.

Abstract: A gas turbine engine bearing support structure comprises a central hub which carries a bearing and which is supported by a plurality of spokes from a ring member. The majority of the spokes are radially extending so that each is perpendicular to an imaginary tangent at its point of intersection with the ring member. However, two of the spokes are not perpendicular but are inclined so that compressive loading on the spokes results in partial rotation of the central hub, thereby leading to compressive loads in the non-inclined spokes being partially relieved by localised bending.

Abstract: According to a preferred embodiment of the present invention, a stage of turbine exhaust exit guide vanes is supported at their outer ends by attachment to the outer turbine exhaust case in a manner permitting upstream and downstream rocking of the vanes, while the inner vane ends engage the upstream end of a sheet metal fairing which defines the radially inner surface of the exhaust gas flow path. The fairing is cantilever supported at its downstream end and is spaced radially outwardly from the inner turbine exhaust case. The inner vane ends are free to move radially relative to the fairing which provides only axial support therefor. Hollow struts disposed immediately downstream of the guide vanes extend between the inner and outer exhaust cases and pass through openings in the fairing which is preferably corrugated in the axial direction to reduce vibration.