Abstract: Disclosed is a deflector disc of a disc tube membrane module, including a deflector disc body, radial water distribution ribs, an inner support ring and an outer support ring. Bulges are arranged on the front and back sides of the deflector disc body; first and second ends of the radial water distribution rib are respectively fixedly connected with an inner edge of the deflector disc body and an outer edge of the inner support ring, an annular boss is arranged on the front side of the inner support ring, a seal ring groove is respectively arranged at corresponding positions of the front and back sides of the inner support ring, multiple yielding water collecting grooves are annularly and uniformly distributed on the inner surface of the inner support ring; an inner edge of the outer support ring is fixedly connected with an outer edge of the deflector disc body.

Abstract: A filter assembly includes a support fame, a filter media, and a conditioning device. The filter media is coupled to the support frame. The filter media has a dirty side that receives an air stream and a clean side that outputs the air stream after having been filtered by the filter media. The conditioning device is coupled to the support frame. The conditioning device is positioned downstream of the clean side of the filter media with respect to the air stream and directly contacts the clean side of the filter media.

Abstract: Various embodiments of an airfoil and machines with airfoils are disclosed. The airfoils include a thicker leading airfoil portion and a thinner trailing airfoil portion. In one embodiment, the leading airfoil portion is formed by bending a body of the airfoil back toward itself. In another embodiment, the leading airfoil portion has a solid geometry and includes two elliptic surfaces. To prevent detachment of airflow, the leading airfoil portion includes at least two arc portions or surfaces that act to direct the airflow down to the trailing airfoil portion in a manner that stabilizes vortexes that may form in the region of changing thickness.

Abstract: A rectification structural body includes an inlet port into which air from an air cleaner flows, an outlet port from which air flows out toward an airflow sensor, and a chamber provided between the inlet port and the outlet port. The inlet port and the outlet port are provided in such directions and at such positions that an air flow is bent in the chamber. The chamber includes two cases of a first case and a second case, the chamber being divided into the two cases.

Abstract: Fluid flow enhancing devices disclosed herein are adapted to enhance flow of fluid through subsurface watershed conduits, for example, culverts, drainpipe and the like. Such fluid flow enhancing devices advantageously enhance watershed runoff functionality in subsurface watershed conduits by altering watershed flow from a parabolic flow pattern to a rotational flow pattern while still accommodating fish passage requirements. This change in flow pattern beneficially provides turbulence that disrupts and flushes debris out of the subsurface watershed conduits. This disruption and flushing establishes a passive cleaning functionality within the subsurface watershed conduits that serves to clean the subsurface watershed conduits after suitable upstream water delivery event (e.g., heavy rain, controlled water release, etc.).

Abstract: A fluid flow resistor includes: a body having entry and exit fluid flow ports, and an internal fluid flow path fluidly extending between the entry and exit fluid flow ports; the internal fluid flow path having a first spiral fluid flow path in a first spiral direction, and a second spiral fluid flow path in a second spiral direction opposite the first spiral direction; each of the first spiral flow path and the second spiral flow path having a plurality of discrete flow chambers fluidly connected in series via interconnecting fluid flow restriction passages; the first and second spiral flow paths having a connecting fluid flow path therebetween; the fluid flow resistor being configured to resistively permit fluid flow from the entry fluid flow port to the exit fluid flow port via the first spiral flow path, the connecting fluid flow path, and the second spiral flow path, in succession.

Abstract: A flow control device is described comprising a generally cylindrical cage 12 including a series of perforations 14 defining, in part, convoluted flow paths between inner and outer peripheries of the device 10, and fences 18 restricting axial flow along at least one of the inner and outer periphery of the cage 12, wherein at least one of the fences 18 is shaped to include a first section 18a at a first axial position, a second section 18b at an axial position spaced from the first section 18a, and interconnecting sections 18c interconnecting the first and second sections 18a, 18b.

Abstract: A sequencing manifold for the purpose of supplying control and supply services of pre-determined temporal sequences to fluid processing assemblies is provided. The functioning of this sequencing manifold requires that translation be applied to the sequencing ports. Actuator mechanisms may supply such translation as either continuous motion or as a series of stepwise motions. Actuator mechanism can be obtained that rely on only mechanical means without the need for a source of electricity. With such actuators, it becomes feasible to conduct the operations of fluid processing assemblies in remote and primitive locations that lack a source of electricity. One skilled in the mechanical arts can provide various actuator mechanisms to meet these requirements.

Abstract: The present disclosure relates to a method for measuring flow velocity or volume flow of a medium using a magneto inductive flow measuring device and to an arrangement having a magneto inductive flow measuring device, as well as to a filling plant with an arrangement, wherein the medium has a low conductivity. A high accuracy of measurement is achieved by provision of a first narrowing of a medium-containing pipeline and/or a second narrowing of a medium-containing measuring tube, wherein the pipeline leads the medium to a measuring tube of the flow measuring device.

Abstract: An engine intake duct includes an upstream side linear portion, a bend portion, a downstream side linear portion, and a fin that rises from an inner surface of the bend portion on an inner side in a bend direction. A fin tip portion is located in the bend portion, and a fin rear end portion is located in the bend portion or the downstream side linear portion, and the fin includes a tip side inclined surface, a rear end side inclined surface, and a rear end surface that is a steep wall extending from a rear end of the rear end side inclined surface to the fin rear end portion. At least a part of a top of the tip side inclined surface of the fin is formed along an extension line of an inner surface of the upstream side linear portion toward the bend portion.

Abstract: Fluid flow enhancing devices disclosed herein are adapted to enhance flow of fluid through subsurface watershed conduits, for example, culverts, drainpipe and the like. Such fluid flow enhancing devices advantageously enhance watershed runoff functionality in subsurface watershed conduits by altering watershed flow from a parabolic flow pattern to a rotational flow pattern while still accommodating fish passage requirements. This change in flow pattern beneficially provides turbulence that disrupts and flushes debris out of the subsurface watershed conduits. This disruption and flushing establishes a passive cleaning functionality within the subsurface watershed conduits that serves to clean the subsurface watershed conduits after suitable upstream water delivery event (e.g., heavy rain, controlled water release, etc.).

Abstract: A fluid processor for use in a downhole pumping operation includes a fluid processing stag, a nozzle stage and a gas compressor stage. The nozzle chamber is configured as a convergent-divergent nozzle and the variable metering member is configured for axial displacement within the convergent section to adjust the open cross-sectional area of the nozzle. A method for producing fluid hydrocarbons from a subterranean wellbore with a pumping system includes the steps of measuring a first gas-to-liquid ratio of the fluid hydrocarbons and operating a motor within the pumping system to operate at a first rotational speed. The method continues with the steps of measuring a second gas-to-liquid ration of the fluid hydrocarbons with the sensor module, where the second gas-to-liquid ratio is greater than the first gas-to-liquid ratio, and operating the motor at a second rotational speed that is faster than the first rotational speed.

Abstract: A engine system is provided with: a plurality of cylinder groups which burn a gas mixture and discharge an exhaust gas; a plurality of high-pressure stage superchargers each having high-pressure stage turbines driven by the exhaust gas from the corresponding cylinder group and high-pressure stage compressors rotated by driving of the high-pressure stage turbines and configured to compress a gas supplied to the corresponding cylinder group; and a plurality of low-pressure stage superchargers having a low-pressure stage turbine driven by an exhaust gas discharged from the high-pressure stage turbine of the high-pressure supercharger which is any one of the plurality of high-pressure stage superchargers, and a low-pressure stage compressor rotated by driving of the low-pressure stage turbine and configured to compress a gas supplied to the high-pressure stage compressor of the high-pressure stage supercharger other than the one high-pressure stage supercharger.

Abstract: A centrifugal compressor for a turbocharger includes an inlet-adjustment mechanism operable to move between an open position and a closed position. The inlet-adjustment mechanism includes a plurality of blades disposed about the compressor air inlet and located within an annular space within the air inlet wall. The blades are pivotable about respective pivot points such that the blades extend radially inward from the annular space into the air inlet when the blades are in the closed position so as to form an orifice of reduced diameter relative to a nominal diameter of the inlet. Downstream surfaces of the blades include vortex reducers that are structured and arranged to reduce a strength of an unsteady vortex generated from the radially inner edges of the blades.

Abstract: A diffuser component for a gas turbine is provided, where a fluid flow in the direction of a combustion chamber of the gas turbine can be slowed down by the diffuser component, and a flow cross-section of the diffuser component, which is defined by a diffuser wall is widened to do so. The diffuser wall is at least locally braced, in that at least one stiffening element with a lattice-type structure is provided on the diffuser wall.

Abstract: A system provides warm, humidified gas to a patient via a patient interface. Horizontal connections can be used between the humidification chamber and conduit. To reduce the likelihood of condensate flowing back to the humidification chamber, or dead space or gases recirculation regions occurring within the gases flow path, a raised portion is positioned inside of the flow path to improve flow characteristics and to provide a barrier for condensate back flow. The raised portion also reduces the amount of condensate that is formed in the system and provides better flow characteristics for sensing purposes.

Abstract: The invention relates to an irradiation chamber (300) for a liquid purification apparatus using ultraviolet light irradiation against the reproduction of pathogenic microorganisms, comprising an inlet portion (302), an outlet portion (303), and a main portion (301) having an elongated shape, the irradiation chamber (300) having an internal surface defining an cavity, the irradiation chamber (300) being provided with ultraviolet light emitting means configured to irradiate liquid in the irradiation chamber (300) with ultraviolet light, the main portion (301) having a shape enlarged compared to the inlet portion (302). The internal surface of the irradiation chamber (300) defining the cavity is a three dimensional rounded surface, having no edge which forms a recess. The invention also relates to a liquid purification apparatus and to a beverage dispenser.

Abstract: A curved portion at an inner circumferential face on a bend direction inside of a bend has a circular arc shape. By configuring the curved portion with a circular arc shape, a recess, serving as an example of a cross-sectional area enlargement portion that enlarges the cross-sectional area of a flow path of a pipe body running along a direction of an axial line 13, is formed in the inner circumferential face on the bend direction inside of the bend.

Abstract: Interlaced tubing elements form a spiral shaped heat exchange element. The tubing elements are tilted while being helically wound, forming a substantially overall cylinder or cone spiral structure having a central longitudinal axis. Tubing elements are tilted with respect to the central longitudinal axis, and may be continuously tilted or variably tilted. A heat exchange element is formed by a continuous tubing element that spirals around a central longitudinal axis, or by several interlaced tubing elements that are spaced adjacent to each other in a conic spiral shape. The tubing elements may have a plurality of fins on at least one of the outer surfaces or first and/or second side walls.

Abstract: A photoresist bottle capable of improving poor coating coverage is disclosed, which comprising: a sealed photoresist bottle body having a connector, a hard groove-shaped projection fixed on the bottom of the bottle body, an inner liner having an opening at the bottom, which is hermetically connected to the groove sidewall of the projection and is used to fill with the photoresist, a nitrogen gas tube inserting into the interspace between the bottle body and the soft liner through the connector, and a photoresist conduit inserting into the soft liner through the connector. Wherein, the top of the inner liner is hermetically connected to the upper lateral wall of the photoresist conduit, the lower end of the photoresist conduit reaches within the groove of the projection. When the soft liner is pressured, since unable to touch the photoresist outlets at the lower end of the photoresist conduit, a blocking can be avoided. Thereby, air bubbles and coating problems are prevented.

Abstract: A coupling means (8;8?;8?,14) serves for connecting a suction channel (27) of an electrosurgical instrument (1) to a vacuum source via a suction tubing (11) and/or for guiding an electrical cable (12), that supplies electrical energy from an electrosurgical generator to the electrosurgical instrument (1). The electrosurgical instrument (1) comprises a hollow elongated main body (2) having a first end (7) for securing a first means (3) for application of the electrical energy to a surgical site and an opposite second end (9), which hollow elongated main body (2) has a switch means (5) to be operated by means of an associated actuator (4) to control application of the electrical energy to the surgical site.

Abstract: A gas turbine engine includes an engine static structure housing that includes a compressor section and a turbine section. A combustor section is arranged axially between the compressor section and the turbine section. A core nacelle encloses the engine static structure to provide a core compartment. An oil tank is arranged in the core compartment and is axially aligned with the compressor section. A heat exchanger is secured to the oil tank and arranged in the core compartment.

Abstract: An indoor unit of an air-conditioning apparatus includes vanes, vane shafts and, which are disposed at the ends of the vanes, vane bearings and, which hold the vane shafts and, and motors, each of which is mounted on a corresponding one of the vane shafts and each of which causes a corresponding one of the vanes to rotate. Each of the vane shafts is provided with a rib, and each of the vane bearings, which hold the corresponding vane shafts, is provided with a hook portion. When one of the vane shafts moves by a reference movement amount in a direction toward the corresponding vane shaft, the corresponding rib and the corresponding hook portion engage with each other, so that movement of the vane shaft is restricted.

Abstract: A solar receiver (100) having a radiation capturing element (3) about which is formed a channel (8) through which a working fluid flows such that thermal energy of the radiation capturing element (8) is absorbed by the working fluid, the channel (8) being shaped to provide a uniform cross sectional area along a length thereof between an inlet thereto and an outlet therefrom.

Abstract: A port plate assembly of a hydraulic unit includes a port plate and a journal bearing. The port plate includes a fixed-speed interface side having a fixed-speed interface surface, and a variable-speed interface side having a variable-speed interface surface. A plurality of kidney-shaped apertures is defined at a kidney pitch diameter about a central bore of the port plate between the fixed-speed interface surface and the variable-speed interface surface. The port plate also includes control cylinder interface formed at a control cylinder radial offset from a central axis of the central bore, where a ratio of the control cylinder radial offset to the kidney pitch diameter is between 1.629 and 1.639. The journal bearing is installed in the central bore of the port plate, where the journal bearing provides an interface for a fixed-speed shaft and a variable-speed shaft of the hydraulic unit.

Abstract: A floor-positioned air-conditioning apparatus including a housing including a fan and a heat exchanger; a forward blowing control member rotatably arranged at a forward air outlet formed in a housing front surface at a position near a housing top surface; and an upward blowing control member rotatably arranged at an upward air outlet formed near the housing front surface are included. The forward blowing control member closes the forward air outlet and the upward blowing control member closes the upward air outlet during operation stop. The forward blowing control member closes the forward air outlet and the upward blowing control member is rotated and opens the upward air outlet during cooling operation. The upward blowing control member closes the upward air outlet and the forward blowing control member is rotated and opens the forward air outlet during heating operation.

Abstract: A mixer (19), for an exhaust system (7) for mixing and/or evaporating a liquid (13) in an exhaust gas flow (8), especially for an SCR system (9), includes a plurality of guide blades (21) arranged in a star-shaped pattern. Simplified manufacturability of the mixer (19) is achieved if the guide blades (21) are connected each with a centrally arranged core (23) radially on the inside and if the guide blades (21). The guide blades (21) and the core (23) are formed by an integral cast part (24).

Abstract: A fan for a motor vehicle includes an impeller formed by multiple blades (3) extending radially from a hub (4), and a base supporting the impeller. The impeller is rotated about an axis of rotation by an actuator means and is positioned inside a hollow cylindrical cavity having the same axis and formed by an axial wall (25) attached to the base. The base includes an upstream front wall (22) extending externally in a radial plane with reference to the axis, and an outer wall (23) extending axially from the front wall (22). The front wall (22) has a protrusion (24) bordering the impeller, with the protrusion extending axially upstream with respect to the plane of the front wall (22). The upstream end of the protrusion is situated further upstream than the upstream end of the blades (3) of the impeller.

Abstract: A turbine housing includes a first shell member and a third shell member, which are formed from metal sheets and forming a housing body, and a tongue member, which is fixed to inner circumferential surfaces of the shell members and discrete from the shell members. The tongue member defines an inlet port and a scroll compartment in the housing body.

Abstract: The present invention relates to a fan cylinder bracing system for a cooling tower having a fan deck that extends along a longitudinal axis. The bracing system has a first ring having a first diameter wherein the first ring is located at a first position along the longitudinal axis. It also has a second ring having a second diameter wherein the second ring is located at a second position along the longitudinal axis. Finally, the cylinder bracing system has a first brace connected to the first ring and said second ring, wherein said first brace transfers loads from the first ring to the second ring.

Abstract: In a multi-blade centrifugal fan in which an impeller is provided in a scroll casing in a freely rotatable manner, the scroll casing is provided with an axially expanded portion that forms an air channel at a bottom surface thereof which is expanded in a rotation-axis direction at a radially outer side of an annular flange portion which supports the impeller; and is provided, in a region of an outlet between a tongue portion and a spiral-end portion of the scroll casing in the axially expanded portion, with a protrusion that protrudes radially outward from a radially inner side surface by a predetermined amount so as to directly face an airflow in a circumferential direction.

Abstract: A unitary, skid-type sound attenuator assembly for simultaneously managing sound from multiple sources. The assembly may include a dedicated muffler for each sound source. In turn, each of these mufflers includes an outlet for directing sound toward a location such as between the various mufflers of the assembly so as to provide an added level of noise cancellation. Additionally, the assembly may include an attenuator at such a common central location for further noise reduction. The attenuator may also serve a filtering function, for example where the sound sources are engines and the assembly is utilized for managing exhaust therefrom such as in an oilfield environment.

Abstract: Some embodiments of the present invention provide components for a serpentine fluid reactor which is optimized for one or more objective functions of interest such as pressure drop, erosion rate, fouling, coke deposition and operating costs. The components are designed by computer modeling the components individually and collectively in which the cross section of flow path is substantially circular under industrial conditions to validate the model design and its operation. Then iteratively the component designs are deformed and the operation of the deformed part(s) is modeled and compared to values obtained with other deformed models until the value of the objective function is optimized (e.g. at an extreme) or the change in the objective function is approaching zero.

Abstract: A flow control grid includes a plurality of channel assemblies connected to one another. Each of the plurality of channel assemblies defines a flow straightening section and a flow turning section. The flow turning section has an arcuate segment and a first substantially flat segment. The first substantially flat segment is positioned in the flow straightening section. The arcuate segment extends outwardly from the flow straightening section.

Abstract: A flow meter for measuring the flow of fluid through a pipe. The flow meter has an elongate member attached to an interior surface of the pipe. The elongate member has a leading end, a trailing end, a longitudinal axis, a first side, and a second side. The first side extends from the leading end to the trailing end and defines a cylindrical cross-sectional shape with a radius of curvature corresponding to the radius of curvature of the pipe and extending along an arc of less than 180 degrees. The second side extends from the leading end to the trailing end and is exposed to the interior of the pipe. The second side forms a constriction in a cross-sectional area of the pipe. Pressure sensors determine a pressure differential caused by the elongate member which is used to determine the volume of fluid flowing through the pipe.

Abstract: The present invention provides a transfer line exchanger which is optimized for one or more objective functions of interest such as pressure drop, erosion rate, fouling, coke deposition and operating costs. The transfer line exchanger is designed by computer modeling a transfer line exchanger in which the cross section of flow path is substantially circular and modeling the operation of the transfer line under industrial conditions to validate the model design and its operation. Then iteratively the model design is deformed and the operation of the deformed part is modeled and compared to values obtained with other deformed models until the value of the objective function is optimized (e.g. at an extreme) or the change in the objective function is approaching zero.

Abstract: Various methods and systems are provided for flowing fluid through a passageway block. In one embodiment, a passageway block comprises a first passage and a second passage, each of the first passage and the second passage including inlets and outlets to the passageway block, none of the inlets and outlets being concentric with one another; but within the passageway block, for at least a portion, a third passage concentrically surrounds the second passage.

Abstract: A duct for connection between an exhaust manifold and a high-pressure turbine inlet include a cylindrical duct body defining a longitudinal axis. A frustoconical outlet nozzle connected at one end of the duct body and extending at about eighty-five degrees from the longitudinal axis. The duct further includes an inlet bell connected at the other end of the duct body and extending at about fifty degrees from the longitudinal axis.

Abstract: The present invention is related to a fan device with fluidic air function, wherein the fan device is configured with an air guide frame which provides each air molecule with higher space freedom and surface area existing in the space by more frequent collision and a longer fluidic path. Thus, after propelling from the fan and colliding with the air guide frame by following the swirly blades, the air flow becomes more comfortable and feels like a nature breeze when it touches human skin, and the present invention is applicable in all types of electric fan or any structure blowing the air.

Abstract: A tubular pipe adapted for transporting oil and water may be treated upon its interior surface to reduce frictional pressure of a multiphase oil/water mixture flowing through the pipe. The tubular pipe may have an interior wall and a central cavity. In some instances, the interior surface is provided with a first textured region being adapted for reducing the adhesive forces of transported oil along the interior wall. A second region upon the interior wall may be adapted for reducing the adhesive forces of water along the interior wall of the tubular pipe. In some applications, riblets may be provided upon the interior pipe wall to further reduce the frictional forces of fluid flowing through the central cavity of the pipe.

Abstract: A guide vane of a turbo-compressor has variable turbine geometry, in particular for a motor vehicle. The guide vane has a profile with a lower side, an upper side and a front edge. The guide vane is characterized by a nose which extends along the front edge of the vane, from the front edge of the vane to the upper side of the vane and forms a low pressure on the upper side of the vane when waste gas impacts the guide vane. A guide vane configuration, a turbo-compressor, a motor vehicle and a method for operating this type of turbo-compressor are further disclosed.

Abstract: Some embodiments of the present invention provide components for a serpentine fluid reactor which is optimized for one or more objective functions of interest such as pressure drop, erosion rate, fouling, coke deposition and operating costs. The components are designed by computer modeling the components individually and collectively in which the cross section of flow path is substantially circular under industrial conditions to validate the model design and its operation. Then iteratively the component designs are deformed and the operation of the deformed part(s) is modeled and compared to values obtained with other deformed models until the value of the objective function is optimized (e.g. at an extreme) or the change in the objective function is approaching zero.

Abstract: A fuel nozzle having a flow pathway including a smooth, sharp, or mitered bend prior to a nozzle tip is provided. The fuel nozzle injects fuel into a combustion chamber with an even flow distribution of the fuel and substantially reduces undesirable acoustic resonance encountered in a fuel nozzle body in a combustion system.

Abstract: A method for forming a manifold for use with a heat exchanger is disclosed. The method may involve forming a plurality of vanes. Opposing surfaces of each of the vanes may define a pair of adjacent flow channels for receiving portions of first and second fluids to be flowed through the flow channels. Each of the flow channels may have a changing aspect ratio along its length.

Abstract: An eddy-current-minimizing flow plug has open flow channels formed between the plug's inlet and outlet. Each open flow channel includes (i) a first portion that originates at the inlet face and converges to a location within the plug that is downstream of the inlet, and (ii) a second portion that originates within the plug and diverges to the outlet. The diverging second portion is approximately twice the length of the converging first portion. The plug is devoid of planar surface regions at its inlet and outlet, and in fluid flow planes of the plug that are perpendicular to the given direction of a fluid flowing therethrough.

Abstract: The present invention relates to an improved grill grate wherein an automated cooking oil system is incorporated into the design of said grill grate. The invention includes a grill grate that has a plurality of outlet holes that align the top surface of the grill grate. The invention also includes a cooking oil pumping system that is in connection with the grill grate.

Abstract: A hollow, cylindrical water hammer arrestor includes an axial passage; two externally threaded extensions disposed at both ends respectively, each of the externally threaded extensions having a diameter less than that of the axial passage; a plurality of first rings disposed in the axial passage, each of the first rings having a plurality of teeth formed on an inner surface; and a plurality of second rings disposed in the axial passage, each of the second rings having a smooth inner surface. The first and second rings are alternately disposed from one end of the axial passage to the other end in the axial passage.

Abstract: Disclosed is a device for causing turbulent flow in a tank assembly that includes, inter alia, a base portion and a vane element that extends in an axial direction from the base portion. The vane element has a curved surface formed at a distal end thereof which is adapted and configured to redirect fluid traversing the device axially in a non-axial direction. Still further, a plurality of shoulder elements extend radially outward from the axis of the vane element and are adapted and configured for limiting that axial insertion of the device into a fitting associated with the tank assembly. In an embodiment of the present invention, the vane element includes lateral edges which are adapted and configured for press-fit engagement with an inside diameter of the fitting associate with the tank assembly.

Abstract: A system for conveying fluid includes a conduit segment and a pump disposed downstream of and fluidicly coupled to the conduit segment. The conduit segment has an interior volume for conveying the fluid in a predetermined direction of flow and a plurality of elongate vanes disposed within the interior volume.

Abstract: A pipe, such as a liner for repairing a failing culvert, comprises a continuous wall defining an inner wall surface and an exterior wall surface. The pipe further defines a central fluid passageway extending from an inlet end to an outlet end. The inner wall surface of the pipe defines a waveform-like geometry near the inlet end, said waveform-like geometry including an initial curvature beginning at the inlet end of the pipe and continuing until reaching a predetermined location where an inner diameter of the pipe is minimized, the curvature then continuing with the inner diameter increasing again to a second predetermined location, before the inner diameter again decreases to a third predetermined location and then remains substantially constant along the remaining length of the pipe, thus creating an annular recess in the inner wall surface of the pipe.