Abstract: A component of a gas turbine engine, the component having: an internal cooling cavity extending through an interior of the component; a baffle insert configured to be inserted into the internal cooling cavity; a plurality of trip strips extending upwardly from an exterior surface of the baffle insert; and at least one rib extending upwardly from the exterior surface of the baffle insert, wherein the plurality of trip strips and the at least one rib are spaced from an interior surface of the internal cooling cavity.

Abstract: An article and method of forming an article are provided. The article includes a side wall at least partially defining an inner region and an outer region of the article, the side wall having a first end and a second end, an end wall formed proximal to the first end of the side wall, the end wall defining a tip portion of the article, and a cooling channel formed in the side wall, within the tip portion. The method of forming an article includes positioning a first sheet of material having a channel formed therein over a first end of a body, positioning at least one additional sheet of material over the first sheet of material, and securing the first sheet of material and the at least one additional sheet of material to the body to form a tip portion including a cooling channel formed therein.

Abstract: A gas turbomachine includes a compressor portion, a turbine portion operatively connected to the compressor portion, and a combustor assembly fluidically connected to each of the compressor portion and the turbine portion. A turbine casing includes a body having an outer surface and an inner surface. A clearance control system includes a plurality of fluidically connected fluid channels extending through the turbine casing. The plurality of fluidically connected fluid channels includes a first fluid channel configured to direct a fluid flow in a first axial direction, a circumferential fluid channel configured to direct the fluid flow in a circumferential direction, and a second fluid channel configured to direct the fluid flow in a second axial direction substantially opposite the first axial direction. The first fluid channel includes a first outlet passing through the inner surface, and the second fluid channel including a second outlet passing through the inner surface.

Abstract: An airfoil assembly for use in a gas turbine engine is disclosed. The airfoil assembly includes a root, a tip shroud, and an airfoil located between the root and tip shroud. The airfoil includes a spar and a heat shield arranged around the spar.

Abstract: An airfoil comprises one or more internal cooling circuits. The cooling circuit can further comprise a near wall cooling mesh, fluidly coupling a supply passage to a mesh plenum. The mesh plenum can be disposed adjacent to the external surface of the airfoil having a plurality of film holes extending between the mesh plenum and the external surface of the airfoil. The mesh plenum can further comprise a cross-sectional area sized to facilitate machining of the film holes without damage to the interior of the airfoil.

Abstract: A component for a gas turbine engine according to an exemplary aspect of the present disclosure includes, among other things, a body portion, a cooling circuit disposed within the body portion and including at least a first cavity and a microcircuit in fluid communication with the first cavity. A plunged hole intersects at least a portion of the microcircuit.

Abstract: A turbomachine blade is disclosed including an airfoil including a cooling fluid plenum extending therein and a trailing edge cooling opening extending from the cooling fluid plenum through a trailing edge of the airfoil. A platform may couple the airfoil to a shank, the platform including a trailing edge extending downstream relative to the shank. At least one cooling conduit delivers a cooling fluid radially inward from at least one of the cooling fluid plenum and the trailing edge cooling opening to a wheel space that is adjacent the shank and radially inward from the trailing edge of the platform. A related turbomachine is also disclosed.

Abstract: An airfoil has an airfoil structure that defines a cooling passage for directing a cooling medium through the airfoil structure. A swirl structure is operatively associated with the cooling passage and configured to impart a tangential velocity to the cooling medium flowing through the cooling passage. An airfoil has an airfoil structure that defines a first cooling passage and a second cooling passage for directing cooling medium through the airfoil structure, each cooling passage having a swirl structure that imparts tangential velocity on the cooling medium flowing through the associated cooling passage. A method of making an airfoil that includes forming an airfoil structure that defines a cooling passage for directing a cooling medium through the airfoil structure and forming a swirl structure that is operatively associated with the cooling passage and imparts tangential velocity to the cooling medium flowing through the cooling passage.

Abstract: The invention refers to a method for producing a near-surface cooling passage in a thermally highly stressed component, which includes: a) providing a component which has a surface on a hot side in a region which is to be cooled; b) letting a channel into the surface; c) inserting a cooling tube into the channel; d) filling the channel, with the cooling tube inserted, with a temperature-resistant filling material in such a way that the inserted cooling tube is embedded into the filling material, leaving free an inlet and an outlet; and e) covering the channel, with the cooling tube embedded, with an anti-oxidation, temperature-stable cover layer. The method is inexpensive and can be used in a flexible manner in the most diverse situations in order to save cooling medium or to reduce the thermal load.

Abstract: A vane is provided for use in a fluid flow of a turbine engine. The vane includes a thin-walled radially extending aerodynamic vane body having axially spaced leading and trailing edges, and a radially outer platform. The wall of the vane body includes an outer shell and an inner shell and defines an interior cavity therein for flowing a cooling medium. A radially extending load strut is arranged at the inner shell of the wall of the leading edge of the vane body.

Abstract: A manufacturing method includes providing a substrate having one or more grooves formed therein. One or more coatings having one or more grooves formed therein are disposed on the substrate and in fluid communication with the one or more grooves in the substrate. A cover coating is disposed on a portion of an outermost surface of the one or more coatings, having one or more cooling outlets formed therein and in fluid communication with the one or more grooves in the one or more coatings. The substrate, the one or more coatings and the cover coating define therein a cooling network for cooling a component. A component having a cooling network defined therein a substrate, one or more coatings disposed on at least a portion of the substrate, and a cover coating disposed over at least a portion of an outermost coating of the one or more coatings.

Abstract: A method and system for providing cooling of a turbine component that includes a region to be cooled is provided. A recess is defined within the region to be cooled, and includes an inner face. At least one support projection extends from the inner face. The at least one support projection includes a free end. A cover is coupled to the region to be cooled, such that an inner surface of the cover is coupled to the free end of the at least one support projection, such that at least one cooling fluid passage is defined within the region to be cooled.

Abstract: A bucket assembly and a method for treating a bucket assembly are disclosed. The bucket assembly includes a platform, the platform defining a platform cooling circuit, and an airfoil extending generally radially outward from the platform, the airfoil defining an airfoil cooling circuit. The bucket assembly additionally includes a lower body portion extending generally radially inward from the platform, the lower body portion defining a root and a cooling passage extending from the root, the cooling passage in fluid communication with the airfoil cooling circuit. The bucket assembly further includes a transfer passage defined between and in fluid communication with the airfoil cooling circuit and the platform cooling circuit such that a cooling medium may flow from the airfoil cooling circuit through the transfer passage to the platform cooling circuit.

Abstract: An airfoil includes an airfoil wall having an exterior airfoil surface and an interior surface. The interior surface provides an airfoil cavity. A baffle is arranged in the airfoil cavity and provides a baffle wall having first and second portions spaced from one another on first and second sides. A tube interconnects the first and second portions and is configured to convey fluid through the tube between the first and second sides. The airfoil is cooled by supplying cooling fluid to a baffle arranged within an airfoil. The cooling fluid is passed through baffle cooling holes to a gap between the baffle and airfoil to cool an interior surface of the airfoil. A portion of cooling fluid is conveyed from one gap location to another gap through a tube in the baffle. Another portion of the cooling fluid is passed through film cooling holes in the airfoil.

Abstract: A gas turbine includes a rotor having a rotor groove and a rotor bore extending through the rotor, the rotor bore having a diffuser-shaped rotor bore exit. A blade is attached to the rotor and includes a blade tip having at least one dust hole. An airfoil has a leading edge and a trailing edge extending along a longitudinal axis of the blade between a lower end of the airfoil and the blade tip. A blade root is disposed at the lower end of the airfoil and is configured to be removably disposed in the rotor groove. The blade root includes a blade inlet having a cross sectional area that exceeds a cross sectional area of the rotor bore in at least one direction. A hollow blade core is disposed in the airfoil and extends along the longitudinal axis of the blade between the blade root and the blade tip.

Abstract: A rotor blade includes an airfoil having a tip plate that extends across an outer radial end. A rim extends radially outward from the tip plate and surrounds at least a portion of the airfoil and includes a concave portion opposed to a convex portion. A plurality of dividers extend between the concave and convex portions to define a plurality of pockets between the concave and convex portions at the outer radial end. A plurality of cooling passages through the tip plate provide fluid communication through the tip plate to the plurality of pockets. A first fluid passage in at least one divider provides fluid communication between adjacent pockets across the at least one divider.

Abstract: A turbine rotor blade for a gas turbine engine is described. The turbine rotor blade includes an airfoil that includes a tip at an outer radial end. The tip includes a rail that defines a tip cavity; and the rail includes a circumscribing rail microchannel. The circumscribing rail microchannel is a microchannel that extends around at least a majority of the length of the inner rail surface.

Abstract: An airfoil comprises pressure and suction surfaces extending from a root section to a tip section of the airfoil. The airfoil also comprises a leading edge and trailing edge defining a chord length therebetween. A tip shelf is formed along the tip section between the pressure surface and a tip shelf wall, the tip shelf wall being spaced between the pressure surface and the suction surface. A squealer pocket is formed along the tip section between the tip shelf wall and a squealer tip wall extending from the suction surface. The tip shelf extends from within 10% of the cord length measured from the leading edge to within 10% of the chord length measured from the trailing edge. The squealer pocket extends from within 10% of the chord length measured from the leading edge to terminate less than 85% of the chord length measured from the trailing edge.

Abstract: A rotor blade for a turbine of a combustion turbine engine having an airfoil that includes a pressure and a suction sidewall defining an outer periphery and a tip portion defining an outer radial end. The tip portion includes a rail that defines a tip cavity. The airfoil includes an interior cooling passage configured to circulate coolant. The rotor blade further includes: a slotted portion of the rail; and at least one film cooling outlet disposed within at least one of the pressure sidewall and the suction sidewall of the airfoil. The film cooling outlet includes a position that is adjacent to the tip portion and in proximity to the slotted portion of the rail.

Abstract: A component wall in a turbine engine includes a substrate and at least one cooling passage that extends through the substrate for delivering cooling fluid from a chamber associated with an inner surface of the substrate to an outer surface of the substrate. Each cooling passage is divided into at least two branches that receive cooling fluid from an entrance portion of the cooling passage that is in communication with the chamber. The branches each include an intermediate portion that extends transversely from the entrance portion and that receives cooling fluid from the entrance portion, and an exit portion that extends transversely from the respective intermediate portion. The exit portions receive the cooling fluid from the intermediate portions and deliver the cooling fluid out of the respective branch through exit portion outlets.

Abstract: A turbine rotor blade used in a gas turbine engine, which includes an airfoil having a tip at an outer radial edge, is described. The airfoil includes a pressure sidewall and a suction sidewall that join together at a leading edge and a trailing edge of the airfoil, the pressure sidewall and the suction sidewall extending from a root to the tip. The tip includes a tip plate and, disposed along a periphery of the tip plate, a rail. The rail includes a microchannel connected to a coolant source.

Abstract: Multi-component vane segment and method for forming the same. Assembly includes: positioning a pre-formed airfoil component (12) and a preformed shroud heat resistant material (18) in a mold, wherein the airfoil component (12) and the shroud heat resistant material (18) each comprises an interlocking feature (24); preheating the mold; introducing molten structural material (46) into the mold; and solidifying the molten structural material such that it interlocks the pre-formed airfoil component (12) with respect to the preformed shroud heat resistant material (18) and is effective to provide structural support for the shroud heat resistant material (18). Surfaces between the airfoil component (12) and the structural material (46), between the airfoil component (12) and the shroud heat resistant material (18), and between the shroud heat resistant material (18) and the structural material (46) are free of metallurgical bonds.

Abstract: A turbine blade having a tip including a tip shelf through which pass one or more diffuser cooling holes, the diffuser cooling holes directing the flow of cooling gas along the tip shelf, spreading the flow of cooling gas more evenly along the tip shelf and enhancing the formation of a curtain of cooling air along the tip shelf, leading to lower blade tip temperatures, reduced diversion of cooling air, and greater turbine blade life.

Abstract: A system includes at least one gas turbine blade that includes at least one recess disposed in a surface of the at least one gas turbine blade. The system also includes a porous insert that includes multiple pores that enable a cooling fluid to flow through the porous insert. The system further includes a cover plate, wherein the porous insert is disposed within the at least one recess, and the cover plate is disposed over the porous insert to enclose the porous insert within the at least one recess.

Abstract: An example blade assembly includes, among other things a blade tip having a pressure side and a suction side, and a plurality of grooves within the blade tip. At least one of the grooves has a contour that is different than both a contour of the pressure side and a contour of the suction side.

Abstract: A flow discharge device, such as a compressor bleed outlet discharging into a bypass duct of a gas turbine engine, comprises an outlet panel 46 which is perforated by openings 48, 50 disposed in an array which tapers in the downstream direction with respect to the flow B in the bypass duct. The configuration of the array of openings 48, 50 creates a plume 60 of tapering form, which enables the bypass flow B to come together downstream of the plume 60 with minimal wake generation, to provide a shield of cooler air so as to avoid contact between the hot gas plume 60 and a wall of 27 of the bypass duct 22. The resulting aerofoil-shaped cross section of the plume 60 also reduces any blocking effect in the bypass duct 22, with consequent performance benefits for the engine fan.

Abstract: The present invention relates to a flow discharge device (30) for discharging a flow of gas (F) from a first gaseous fluid (A) into a second gaseous fluid (B) which is of a lower pressure than the first gaseous fluid. The discharge device comprises a valve (34) disposed between the first and second gaseous fluids and arranged to regulate the discharge flow (F) and a swirler means (50) disposed between the valve (34) and the second gaseous fluid. The swirler means (50) comprises a plurality of radially extending circumferentially spaced vanes (61, 63, 65). In use the swirler means (50) swirls the discharge flow (F). This acts to reduce the energy, and therefore the pressure of the discharge flow. This results in quieter operation.

Abstract: A system includes a gas turbine combustor, which includes a combustion liner disposed about a combustion region, a flow sleeve disposed about the combustion liner, an air passage between the combustion liner and the flow sleeve, and a structure between the combustion liner and the flow sleeve. The structure obstructs an airflow through the air passage. The gas turbine combustor also includes a wake reducer disposed adjacent the structure. The wake reducer directs a flow into a wake region downstream of the structure.

Abstract: An air cooled turbine blade including leading and trailing edges, and pressure and suction side walls extending between the leading and trailing edges. Leading and trailing edge cooling circuits extend spanwise adjacent to the leading and trailing edges, respectively. A forward flow mid-section serpentine cooling circuit extends spanwise and is located between the leading and trailing edge cooling circuits. An axial tip cooling circuit extends in the chordal direction and is located between a tip cap of the blade and the serpentine cooling circuit at an outer end of the serpentine cooling circuit. The axial tip cooling circuit has a forward end receiving cooling air from a final channel of the serpentine cooling circuit and discharges the cooling air adjacent to the trailing edge.

Abstract: Gas turbine blades which simplify the formation of cooling channels provided inside the turbine blades while simultaneously avoiding loss of turbine blade strength and rigidity due to forming of the cooling channels. Cooling channels provided in the interior of a gas turbine blade include a plurality of straight channel-like base-side elongated holes extending in a longitudinal direction at a base side of the turbine blade, a plurality of straight channel-like tip-side elongated holes extending in a longitudinal direction at a tip side of the turbine blade, and a plurality of communicating hollow portions interposed at connection portions between the two types of elongated holes to allow the two types of elongated holes to communicate with each other, and have larger cross-sectional areas than the channel cross-sectional areas of both elongated holes. The communicating hollow portions are formed to match the position of a platform portion of the turbine blade.

Abstract: A turbine blade includes a first side wall including a first tip edge, a second side wall opposite the first side wall and including a second tip edge, a tip wall between the first and second side walls, the tip wall recessed from the first tip edge of the first side wall and the second tip edge of the second side wall forming a coolant cavity, a tip recess cavity, a first parapet wall on the first side wall, and a second parapet wall on the second side wall, the coolant cavity defined by the tip wall, and the tip recess cavity defined by the tip wall, and the first and second parapet walls, a step formed between the first tip edge and the tip wall, a cooling hole through the first parapet wall, the step, and the tip wall, the cooling hole including an open and a closed channel section.

Abstract: A turbine bucket may generally include an airfoil formed from a metal-based material. The airfoil may include a base and a tip disposed opposite the base. The airfoil may also include a pressure side wall and a suction side wall extending between a leading edge and a trailing edge. Additionally, the turbine bucket may include a tip cap disposed between the pressure side wall and the suction side wall. The tip cap may be formed from a ceramic matrix composite material.

Abstract: A turbine bucket is provided and includes a shank interconnectable with a rotor and formed to accommodate coolant therein and an airfoil blade coupled to a radially outward portion of the shank and including a body formed to define a substantially radially extending cooling hole therein, which is disposed to be solely receptive of the coolant accommodated within the shank for removing heat from the body, the cooling hole being further defined as having a substantially non-circular cross-sectional shape at a predefined radial position of the body.

Abstract: A turbine rotor blade with a tip section having a pressure side and suction side tip rail that forms a squealer pocket. A number of chordwise extending ribs formed within the squealer pocket form vortex cooling channels that extend from the leading edge region and open along the pressure side tip peripheral wall. A row of tip cooling holes opens into each of the vortex cooling channels to discharge cooling air and form a vortex flow within the channels that provides both sealing and cooling for the blade tip.

Abstract: A squealer tip formed from a pressure side rib and a suction side rib extending radially outward from a tip of the turbine blade is disclosed. The pressure and suction side ribs may be positioned along the pressure side and the suction side of the turbine blade, respectively. The pressure and suction side ribs may include chamfered leading edges with film cooling holes having exhaust outlets positioned therein. The film cooling holes may be configured to be diffusion cooling holes with one or more tapered sections for reducing the velocity of cooling fluids and increasing the size of the convective surfaces.

Abstract: A turbine blade including an open cavity at its distal tip, the cavity being defined by a bottom wall and a side wall extending along the perimeter of the distal tip in an extension of the upper and lower walls of the blade, the side wall of the cavity including an opening in a vicinity of the leading edge of the blade opening into the cavity. A deflector extends at least in the middle portion of the cavity between the leading edge and the trailing edge.

Abstract: Cooling channels through the interior of a machine component that include: a first set of cooling channels, the first set of cooling channels including a plurality of parallel channels that reside in a first plane; a second set of cooling channels, the second set of cooling channels including a plurality of parallel channels that reside in a second plane. Along a longitudinal axis, the cooling channels of the first and second set of cooling channels may include an alternating diverging-converging configuration, the alternating diverging-converging configuration creating a series of broader chamber sections connected by a series of narrower throat sections. The first set of cooling channels and the second set of cooling channels may be configured such that, when viewed from the side, a crisscrossing pattern with a plurality of intersections is formed.

Abstract: A system, in one embodiment, includes a turbine blade having a radial blade tip. The system further includes a trailing edge trench that is formed in the radial blade tip and which extends towards a trailing edge of the turbine blade. The trailing edge trench further includes a first set of cooling passages, each of which includes a first slot formed along a first sidewall of the trailing edge trench, whereby the slot is coupled to a first respective hole extending through a floor of the trailing edge trench.

Abstract: A squealer tip preform having a coating including an abrasive is disclosed. The squealer tip may be separately formed from a generally elongated blade to which the squealer tip preform is configured to be attached. The squealer tip may be configured such that an outer surface of the squealer tip preform is generally aligned with an outer side surface of the turbine blade defining a cross-sectional profile of the turbine blade. Forming the squealer tip preform with an abrasive coating separate from the turbine blade greatly reduces costs and improves efficiency as compared with conventional systems.

Abstract: A blade cooling structure of a gas turbine, which can reduce the pressure loss of a cooling medium without decreasing the heat transfer coefficient, is provided. The blade cooling structure comprises a cooling passage (15) for flowing cooling air (A) from a proximal end portion (12) toward a blade portion (14) of a moving blade (11), a plurality of turbulators (21) arranged, on both wall surfaces of the cooling passage (15) opposing each other, in such a manner as to be inclined with respect to the flowing direction of the cooling air (A), and a plurality of dimples (22) formed in a downstream region (N) downstream of a center position (O) in the flowing direction of the cooling air (A) on the wall surface of the cooling passage (15) between the adjacent turbulators (21).

Abstract: An aspect of the invention is a turbine blade for a gas turbine, comprising a blade root, adjoining which one after the other are a platform region having a transversely running platform and then a blade profile curved in the longitudinal direction, comprising at least one cavity which is open on the root side and through which a coolant can flow and which extends through the blade root and the platform region into the blade profile. The cavity is surrounded by an inner wall, on the surface of which structural elements influencing the coolant are provided. In order to prolong the service life of such a turbine blade, the invention proposes that a section, lying at least in the blade profile and adjoining the platform region, of the surface of the inner wall be free of structural elements. Such a turbine blade can preferably be used in a stationary gas turbine.

Abstract: An airfoil includes a leading edge, a trailing edge, a suction surface, a pressure surface, and a tip shelf. The suction surface and the pressure surface both extend axially to connect the leading edge to the trailing edge. The suction surface and the pressure surface both extend radially from a root section of the airfoil a tip section of the airfoil. The tip shelf is formed along the tip section, and includes a triangular pocket.

Abstract: An airfoil is provided and includes a body formed to define a substantially radially extending cooling hole therein, which is configured to be receptive of a supply of a coolant for removing heat from the body, and a flag region therein, which is fluidly communicative with the cooling hole and thereby configured to be receptive of a portion of the supply of the coolant such that the coolant portion is directed to form a vortex within the flag region to increase heat removal from the body beyond that provided by the coolant flow through the cooling hole.

Abstract: A turbine rotor blade with a serpentine flow cooling circuit having three legs in which the first leg and the second leg are upward flowing channels each having a series of slanted ribs that define impingement chambers with impingement cooling holes to provide impingement cooling to the airfoil walls. The second leg is a downward flowing leg that contains no metering holes and is substantially unobstructed to the cooling air flow. The rotation of the blade produces a centrifugal force on the airflow passing through the channels with the metering and impingement holes to aid in the flow towards the blade tip. The return channels are unobstructed in order to minimize the pressure loss on the return channel of the serpentine circuit.

Abstract: A composite turbine blade and a method of manufacture thereof is disclosed. The composite turbine blade comprises a turbine blade portion comprising a first material and a first tip plate comprising a second material. The turbine blade portion has an exterior wall and an interior wall surrounding a hollow interior cavity, and a top surface extending from the exterior wall to the interior wall bounding an orifice that is fluidly connected to the hollow interior cavity. The first tip plate may be attached to the turbine blade along the top surface and extending from proximate the exterior wall of the turbine blade across the orifice to cover the orifice.

Abstract: A turbine bucket for a gas turbine engine is described herein. The turbine bucket may include an airfoil, a tip shroud positioned on a tip of the airfoil, and a number of cooling holes extending through the airfoil and the tip shroud. One or more of the cooling holes may include a length of narrowing diameter about the tip shroud and a length of expanding diameter about a surface of the tip shroud.

Abstract: A turbine rotor blade with a hollow open cavity formed between the airfoil walls, and radial flow near wall cooling channels formed within the walls that open on the tip surface to discharge the cooling air for sealing of the tip. The radial channels have a converging flow area to increase the cooling air flow velocity, and the radial cooling channels on the pressure side wall are slanted toward the pressure side so that the discharged cooling air will produce a smaller vena contractor and further reduce tip leakage flow.

Abstract: Gas turbine blades which simplify the formation of cooling channels provided inside the turbine blades while simultaneously avoiding loss of turbine blade strength and rigidity due to forming of the cooling channels. Cooling channels provided in the interior of a gas turbine blade include a plurality of straight channel-like base-side elongated holes extending in a longitudinal direction at a base side of the turbine blade, a plurality of straight channel-like tip-side elongated holes extending in a longitudinal direction at a tip side of the turbine blade, and a plurality of communicating hollow portions interposed at connection portions between the two types of elongated holes to allow the two types of elongated holes to communicate with each other, and have larger cross-sectional areas than the channel cross-sectional areas of both elongated holes. The communicating hollow portions are formed to match the position of a platform portion of the turbine blade.

Abstract: A turbine rotor blade with a cooling air channel formed in a mid-chord region, the channel includes a number of rows of semi-circular shaped ribs that extend across the channel and open toward the blade tip. Adjacent ribs form metering and impingement passages that discharge a jet of cooling air against the rib above it. The open ends of the ribs form vortex generating passages in which the impingement cooling air flows into to form a vortex flow pattern in the cooling air.

Abstract: A turbine rotor blade with a thin thermal skin bonded to a spar to form a near-wall cooled blade, the blade having a near-wall cooling circuit formed by plurality of multiple pass serpentine flow cooling circuits that have cooling channels formed within the airfoil walls and the platform, and with a row of cooling air exit slots that connect to the last leg of the serpentine flow cooling channels and open onto an upstream side of the tip edge so that cooling air is discharged to form a blockage for the blade tip. The airfoil walls include radial extending cooling channels that form the airfoil legs of the serpentine cooling circuits.