US20140064942A1 - Turbine rotor blade platform cooling - Google Patents
Turbine rotor blade platform cooling Download PDFInfo
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- US20140064942A1 US20140064942A1 US13/600,756 US201213600756A US2014064942A1 US 20140064942 A1 US20140064942 A1 US 20140064942A1 US 201213600756 A US201213600756 A US 201213600756A US 2014064942 A1 US2014064942 A1 US 2014064942A1
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- rib
- cooling
- edge
- cooling chamber
- channel width
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
- F01D5/12—Blades
- F01D5/14—Form or construction
- F01D5/18—Hollow blades, i.e. blades with cooling or heating channels or cavities; Heating, heat-insulating or cooling means on blades
- F01D5/186—Film cooling
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
- F01D5/12—Blades
- F01D5/14—Form or construction
- F01D5/18—Hollow blades, i.e. blades with cooling or heating channels or cavities; Heating, heat-insulating or cooling means on blades
- F01D5/187—Convection cooling
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
- F05D2240/00—Components
- F05D2240/80—Platforms for stationary or moving blades
- F05D2240/81—Cooled platforms
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T50/00—Aeronautics or air transport
- Y02T50/60—Efficient propulsion technologies, e.g. for aircraft
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Turbine Rotor Nozzle Sealing (AREA)
Abstract
A cooling arrangement in a platform in a rotor blade or a sidewall in a stator blade in a turbine of a combustion turbine engine is described. The cooling arrangement may include: a cooling chamber configured to pass coolant from an inlet to an outlet; and a rib positioned within the cooling chamber. The rib may partially divide the cooling chamber so to form a switchback. The rib may be canted with respect to the cooling chamber such that the switchback has an ever narrowing channel.
Description
- The present application relates generally to combustion turbine engines, which, as used herein and unless specifically stated otherwise, includes all types of combustion turbine engines, such as those used in power generation and aircraft engines. More specifically, but not by way of limitation, the present application relates to apparatus, systems and/or methods for cooling the platform region of turbine rotor blades and the sidewall region of turbine stator blades.
- A gas turbine engine typically includes a compressor, a combustor, and a turbine. The compressor and turbine generally include rows of airfoils or blades that are axially stacked in stages. Each stage typically includes a row of circumferentially spaced stator blades, which are fixed, and a set of circumferentially spaced rotor blades, which rotate about a central axis or shaft. In operation, the rotor blades in the compressor are rotated about the shaft to compress a flow of air. The compressed air is then used within the combustor to combust a supply of fuel. The resulting flow of hot gases from the combustion process is expanded through the turbine, which causes the rotor blades to rotate the shaft to which they are attached. In this manner, energy contained in the fuel is converted into the mechanical energy of the rotating shaft, which then, for example, may be used to rotate the coils of a generator to generate electricity.
- Referring to
FIGS. 1 and 2 ,turbine rotor blades 100 generally include an airfoil portion orairfoil 102 and a root portion orroot 104. Theairfoil 102 may be described as having aconvex suction face 105 and aconcave pressure face 106. Theairfoil 102 further may be described as having a leadingedge 107, which is the forward edge, and atrailing edge 108, which is the aft edge. Theroot 104 may be described as having structure (which, as shown, typically includes a dovetail 109) for affixing theblade 100 to the rotor shaft, aplatform 110 from which theairfoil 102 extends, and ashank 112, which includes the structure between thedovetail 109 and theplatform 110. - As illustrated, the
platform 110 may be substantially planar. More specifically, theplatform 110 may have aplanar topside 113, which, as shown inFIG. 1 , may include an axially and circumferentially extending flat surface. As shown inFIG. 2 , theplatform 110 may have aplanar underside 114, which may also include an axially and circumferentially extending flat surface. Thetopside 113 and thebottom side 114 of theplatform 110 may be formed such that each is substantially parallel to the other. As depicted, it will be appreciated that theplatform 110 typically has a thin radial profile, i.e., there is a relatively short radial distance between thetopside 113 and thebottom side 114 of theplatform 110. - In general, the
platform 110 is employed onturbine rotor blades 100 to form the inner flow path boundary of the hot gas path section of the gas turbine. Theplatform 110 further provides structural support for theairfoil 102. In operation, the rotational velocity of the turbine induces mechanical loading that creates highly stressed regions along theplatform 110 that, when coupled with high temperatures, ultimately cause the formation of operational defects, such as oxidation, creep, low-cycle fatigue cracking, and others. These defects, of course, negatively impact the useful life of therotor blade 100. It will be appreciated that these harsh operating conditions, i.e., exposure to extreme temperatures of the hot gas path and mechanical loading associated with the rotating blades, create considerable challenges in designing durable, long-lastingrotor blade platforms 110 that both perform well and are cost-effective to manufacture. - One common solution to make the
platform region 110 more durable is to cool it with a flow of compressed air or other coolant during operation, and a variety of these type of platform designs are known. However, as one of ordinary skill in the art will appreciate, theplatform region 110 presents certain design challenges that make it difficult to cool in this manner. In significant part, this is due to the awkward geometry of this region, in that, as described, theplatform 110 is a periphery component that resides away from the central core of the rotor blade and typically is designed to have a structurally sound, but thin radial thickness. - To circulate coolant,
rotor blades 100 typically include one or more hollow cooling passages 116 (seeFIGS. 3 , 4, 5, and 9) that, at minimum, extend radially through the core of theblade 100, including through theroot 104 and theairfoil 102. As described in more detail below, to increase the exchange of heat,such cooling passages 116 may be formed having a serpentine path that winds through the central regions of theblade 100, though other configurations are possible. In operation, a coolant may enter the central cooling passages via one ormore inlets 117 formed in the inboard portion of theroot 104. The coolant may circulate through theblade 100 and exit through outlets (not shown) formed on the airfoil and/or via one or more outlets (not shown) formed in theroot 104. The coolant may be pressurized, and, for example, may include pressurized air, pressurized air mixed with water, steam, and the like. In many cases, the coolant is compressed air that is diverted from the compressor of the engine, though other sources are possible. As discussed in more detail below, these cooling passages typically include a high-pressure coolant region and a low-pressure coolant region. The high-pressure coolant region typically corresponds to an upstream portion of the cooling passage that has a higher coolant pressure, whereas the low-pressure coolant region corresponds to a downstream portion having a relatively lower coolant pressure. - In some cases, the coolant may be directed from the
cooling passages 116 into acavity 119 formed between theshanks 112 andplatforms 110 ofadjacent rotor blades 100. From there, the coolant may be used to cool theplatform region 110 of the blade, a conventional design of which is presented inFIG. 3 . This type of design typically extracts air from one of thecooling passages 116 and uses the air to pressurize thecavity 119 formed between theshanks 112/platforms 110. Once pressurized, thiscavity 119 then supplies coolant to cooling channels that extend through theplatform 110. After traversing theplatform 110, the cooling air may exit the cavity through film cooling holes formed in thetopside 113 of theplatform 110. - It will be appreciated, however, that this type of conventional design has several disadvantages. First, the cooling circuit is not self-contained in one part, as the cooling circuit is only formed after two neighboring
rotor blades 100 are assembled. This adds a great degree of difficulty and complexity to installation and pre-installation flow testing. A second disadvantage is that the integrity of thecavity 119 formed betweenadjacent rotor blades 100 is dependent on how well the perimeter of thecavity 119 is sealed. Inadequate sealing may result in inadequate platform cooling and/or wasted cooling air. A third disadvantage is the inherent risk that hot gas path gases may be ingested into thecavity 119 or the platform itself 110. This may occur if thecavity 119 is not maintained at a sufficiently high pressure during operation. If the pressure of thecavity 119 falls below the pressure within the hot gas path, hot gases will be ingested into theshank cavity 119 or theplatform 110 itself, which typically damages these components as they were not designed to endure exposure to the hot gas-path conditions. -
FIGS. 4 and 5 illustrate another type of conventional design for platform cooling. In this case, the cooling circuit is contained within therotor blade 100 and does not involve theshank cavity 119, as depicted. Cooling air is extracted from one of thecooling passages 116 that extend through the core of theblade 110 and directed aft throughcooling channels 120 formed within the platform 110 (i.e., “platform cooling channels 120”). As shown by the several arrows, the cooling air flows through theplatform cooling channels 120 and exits through outlets in theaft edge 121 of theplatform 110 or from outlets disposed along thesuction side edge 122. (Note that in describing or referring to the edges or faces of therectangular platform 110, each may be delineated based upon its location in relation to thesuction face 105 andpressure face 106 of theairfoil 102 and/or the forward and aft directions of the engine once theblade 100 is installed. As such, as one of ordinary skill in the art will appreciate, the platform may include anaft edge 121, asuction side edge 122, aforward edge 124, and apressure side edge 126, as indicated inFIGS. 3 and 4 . In addition, thesuction side edge 122 and thepressure side edge 126 also are commonly referred to as “slashfaces” and the narrow cavity formed therebetween once neighboringrotor blades 100 are installed may be referred to as a “slashface cavity”.) - It will be appreciated that the conventional designs of
FIGS. 4 and 5 have an advantage over the design ofFIG. 3 in that they are not affected by variations in assembly or installation conditions. However, conventional designs of this nature have several limitations or drawbacks. First, as illustrated, only a single circuit is provided on each side of theairfoil 102 and, thus, there is the disadvantage of having limited control of the amount of cooling air used at different locations in theplatform 110. Second, conventional designs of this type have a coverage area that is generally limited. While the serpentine path ofFIG. 5 is an improvement in terms of coverage overFIG. 4 , there are still dead areas within theplatform 110 that remain uncooled. Third, to obtain better coverage with intricately formedplatform cooling channels 120, manufacturing costs increase dramatically, particularly if the cooling channels having shapes that require a casting process to form. Fourth, these conventional designs typically dump coolant into the hot gas path after usage and before the coolant is completely exhausted, which negatively affects the efficiency of the engine. Fifth, conventional designs of this nature generally have little flexibility. That is, thechannels 120 are formed as an integral part of theplatform 110 and provide little or no opportunity to change their function or configuration as operating conditions vary. In addition, these types of conventional designs are difficult to repair or refurbish. - In certain cases, platform cooling passages are configured with a switchback configuration. Example of such a design is shown in
FIG. 6 . As shown, the switchback design may include acooling chamber 130 that includes aninlet 132 and anoutlet 134, and arib 135 that divides thechamber 130 such that coolant is forced to travel a circuitous route before reaching theoutlet 134. In this manner, the coolant is exposed to the entirety of thecooling chamber 130 so that it may convectively cool the surrounding region. One shortcoming of this type of switchback is that the coolant absorbs heat as it moves through the switchback so that the downstream section receives less cooling than upstream sections, which causes uneven cooling through the platform and the development of component damaging hotspots. It will further be appreciated that the aforementioned issues with rotor blade platform cooling are applicable to sidewall regions within turbine stator blades. - As a result, conventional designs of rotor blade platform and stator blade sidewall cooling configurations are lacking in one or more important areas. There remains a need for improved apparatus, systems, and/or methods that effectively and efficiently cool these blade regions, while also being cost-effective to construct, flexible in application, and durable.
- In one exemplary embodiment, the present application describes a cooling arrangement in a platform in a rotor blade in a turbine of a combustion turbine engine. The cooling arrangement may include: a cooling chamber configured to pass coolant from an inlet to an outlet; and a rib positioned within the cooling chamber. The rib may partially divide the cooling chamber so to form a switchback. The rib may be canted with respect to the cooling chamber such that the switchback comprises an ever narrowing channel.
- The present application further describes a cooling arrangement in a sidewall in a stator blade in a turbine of a combustion turbine engine. The cooling arrangement may include: a cooling chamber configured to pass coolant from an inlet to an outlet; and a rib positioned within the cooling chamber. The rib may partially divide the cooling chamber so to form a switchback. The rib may be canted with respect to the cooling chamber such that the switchback comprises an ever narrowing channel.
- These and other features of the present application will become apparent upon review of the following detailed description of the preferred embodiments when taken in conjunction with the drawings and the appended claims.
- These and other features of this invention will be more completely understood and appreciated by careful study of the following more detailed description of exemplary embodiments of the invention taken in conjunction with the accompanying drawings, in which:
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FIG. 1 illustrates a perspective view of an exemplary turbine rotor blade in which embodiments of the present invention may be employed; -
FIG. 2 illustrates an underside view of a turbine rotor blade in which embodiments of the present invention may be used; -
FIG. 3 illustrates a sectional view of neighboring turbine rotor blades having a cooling system according to conventional design; -
FIG. 4 illustrates a top view of a turbine rotor blade having a platform with interior cooling channels according to conventional design; -
FIG. 5 illustrates a top view of a turbine rotor blade having a platform with interior cooling channels according to an alternative conventional design; -
FIG. 6 illustrates a top with partial cross-sectional view of a turbine rotor blade having a platform with interior cooling channel having a switchback configuration according to a conventional design; -
FIG. 7 illustrates a top with partial cross-sectional view of a platform of a turbine rotor blade having a cooling configuration according to an exemplary embodiment of the present invention; -
FIG. 8 is a side cross-sectional view along line 8-8 ofFIG. 7 ; -
FIG. 9 illustrates a top with partial cross-sectional view of a platform of a turbine rotor blade having a cooling configuration according to an alternative embodiment of the present invention; -
FIG. 10 illustrates a top with partial cross-sectional view of a platform of a turbine rotor blade having a cooling configuration according to an alternative embodiment of the present invention; -
FIG. 11 illustrates a top with partial cross-sectional view of a platform of a turbine rotor blade having a cooling configuration according to an alternative embodiment of the present invention; -
FIG. 12 illustrates a graph depicting “Flow Parameters” against “Total Flow Distance Through Switchback” according to experimental data on embodiments of the present invention; -
FIG. 13 illustrates a side view of a turbine stator blade showing the positioning of cooling configuration according to an alternative embodiment of the present invention; and -
FIG. 14 illustrates a top with partial cross-sectional view of a sidewall of a turbine stator blade having a cooling configuration according to an alternative embodiment of the present invention. - As discussed above, various conventional designs of
internal cooling passages 116 are somewhat effective at cooling certain regions within arotor blade 100. However, as one of ordinary skill in the art will appreciate, the platform region proves more challenging. This is due, at least in part, to the platform's awkward geometry—i.e., its narrow radial height and the manner in which it juts away from the core or main body of therotor blade 100. Nevertheless, given its exposures to the extreme temperatures of hot gas path and high mechanical loading, the cooling requirements of theplatform 110 are considerable. As described above, conventional platform cooling designs are ineffective because they fail to address the particular challenges of the region, are inefficient with their usage of coolant, and/or are costly to fabricate. It will be further appreciated that the sidewalls of stator blades present similar issues and deficiencies with conventional approaches, which will be discussed in more detail in relation toFIGS. 12 and 13 , - Several particular descriptive terms may be used to describe exemplary embodiments of the present application. The meaning for these terms shall include the following definitions. The terms “downstream” and “upstream” are terms that indicate a direction relative to the flow of working fluid through the turbine or, as the case may be, coolant through a cooling passage. Accordingly, the term “downstream” means the direction of the flow, and the term “upstream” means in the opposite direction of the flow. The term “radial” refers to movement or position perpendicular to an axis. It is often required to describe parts that are at differing radial positions with regard to this axis. In these cases, if a first component resides closer to the axis than a second component, it may be stated herein that the first component is either “inboard” or “radially inward” of the second component. If, on the other hand, the first component resides further from the axis than the second component, it may be stated herein that the first component is “outboard” or “radially outward” of the second component. The term “axial” refers to movement or position parallel to an axis. And, the term “circumferential” refers to movement or position around an axis. Unless otherwise stated, when the terms “radial”, “axial”, or “circumferential” are used, they are used in reference to the central axis of the turbine engine.
- Referring now to
FIGS. 7 through 11 , several views of exemplary embodiments of the present invention are provided. In particular,rotor blades 100 having aplatform cooling configuration 130 according to preferred embodiments of the present invention are illustrated. As shown, therotor blade 100 includes aplatform 110 residing at the interface between anairfoil 102 and aroot 104. A coolingchamber 130 may be formed within theplatform 110. For example, as illustrated inFIG. 7 , the coolingchamber 130 may be positioned near theforward edge 124 of theplatform 110. The coolingchamber 130 may include aninlet 132 and anoutlet 134. Theinlet 132 may be supplied with coolant through a variety of ways, such as through an internal coolant passageway through therotor blade 110 or via theshank cavity 119. During operation, a coolant may be directed through thecooling chamber 130, traveling from aninlet 132 to anoutlet 134. Arib 135 may be positioned within thecooling chamber 130. Therib 135 may be configured to partially divide thecooling chamber 130 so that a serpentine or switchback path (hereinafter “switchback 131”) is formed. As discussed in more detail below, therib 135 may be canted with respect to thecooling chamber 130. According to embodiments of the present invention, therib 135 may be canted at an angle so that theswitchback 131 has an ever narrowing channel. - In certain preferred embodiments, the ever narrowing channel of the present invention is one that narrows at a constant rate as it extends from the
inlet 132 to theoutlet 134 of thecooling chamber 130. In other preferred embodiments, the ever narrowing channel, as used herein, is defined as a channel that narrows at a constant rate along both of the flanks of therib 135. More specifically, theswitchback 131 may be described as having a pass positioned on each flank of therib 135. These passes may be referred to as: an upstream pass 138 (because it coincides with the side of therib 135 on which theinlet 132 is located); and a downstream pass 139 (because it coincides with the side of therib 135 on which theoutlet 134 is located). Additionally, it will be appreciated that between theupstream pass 138 and thedownstream pass 139, theswitchback 131 may be described as having a turn-section 142. The turn-section 142 may define a turn of approximately 180°. - The cooling
chamber 130 may have a planar configuration that is aligned with and contained within theplatform 110 or a specific region of theplatform 110. As used herein, an “outboard profile” of thecooling chamber 130 refers to the profile as seen from a position outboard of theplatform 110, which, it will be appreciated, is the perspective shown inFIGS. 7 and 9 through 11. It will be appreciated that in certain embodiments thecooling chamber 130 may be offset from a curved surface, such as aplatform 110 having a topside 113 that includes an area of more pronounced curvature. In certain embodiments, the outboard profile of thecooling chamber 130 may be that of a quadrilateral, i.e., have four linear sides. Therib 135, as shown, may be linear in configuration. In certain embodiments, the outboard profile of thecooling chamber 130 is a parallelogram. More specifically, the outboard profile of thecooling chamber 130 may be that of a square, a rhombus, or a rectangle. - As shown most clearly in
FIG. 8 , theplatform 110 includes aplanar topside 113. (Note that “planar,” as used herein, means approximately or substantially in the shape of a plane. For example, one of ordinary skill in the art will appreciate that a platform is configured to have an outboard surface that is slight curved and convex, with the curvature corresponding to the circumference of the turbine at the radial location of the rotor blades. As used herein, this type of platform shape is deemed planar, as the radius of curvature is sufficiently great to give the platform a flat appearance.) The coolingchamber 130 may include aplanar ceiling 168 that is just inboard of thetopside 113 of theplatform 110, as well as aplanar floor 169 radially offset from theceiling 168. The radial height of thecooling chamber 130 may be described as the radial offset between theceiling 168 and thefloor 169. As illustrated, in preferred embodiments, the radial height of thecooling chamber 130 is substantially constant. Therib 135 extends from thefloor 169 to theceiling 168 of thecooling chamber 130. - The quadrilateral profile of the
cooling chamber 130 may be described as including a first pair and a second pair of opposing sides or edges, each pair including two edges of the quadrilateral that oppose each other across the coolingchamber 130. The first pair of opposing edges includes afirst edge 151 and asecond edge 152, and the second pair of opposing edges includes athird edge 153 and afourth edge 154. - In certain preferred embodiments, the
inlet 132 and theoutlet 134 are positioned along thefirst edge 151 of thecooling chamber 130, and, between theinlet 132 and theoutlet 134, afirst end 157 of therib 135 may be disposed that separates theinlet 132 from theoutlet 134. From thefirst end 157, therib 135 extends toward thesecond edge 152 of thecooling chamber 130, but terminates at a location short of thesecond edge 152. That termination point will be referred to herein as thesecond end 158 of therib 135. That is, thesecond end 158 of therib 135 is offset a distance from thesecond edge 152, thereby forming the turn-section 142 that redirects the flow of coolant toward theoutlet 134. Therib 135, as stated, is canted with respect to thecooling chamber 130. As illustrated inFIG. 7 , the cant of therib 135 may be relative to the longitudinal axis of thecooling chamber 130. In a preferred embodiment, therib 135 is canted such that a channel width of theupstream pass 138 decreases at a linear rate as theupstream pass 138 extends from theinlet 132 to thesecond end 158 of therib 135. Further, therib 135 may be canted such that a channel width of thedownstream pass 139 decreases at a linear rate as thedownstream pass 139 extends from thesecond end 158 of therib 135 to theoutlet 134. The channel width of the downstream end of theupstream pass 138 may be just greater than a channel width of an upstream end of thedownstream pass 139. It will be appreciated that, in a preferred embodiment, therib 135 is canted toward thethird edge 153 such that, as therib 135 extends from thefirst edge 151 toward thesecond edge 152, the distance between therib 135 and thethird edge 153 decreases while a distance between therib 135 and thefourth edge 154 increases. - The angle or cant of the
rib 135 may be described by the relationship it maintains with respect to the longitudinal axis of thecooling chamber 130. It will be recognized that, in the case when the third 153 andfourth edges 154 are parallel, a reference line that extends through the midpoints between thethird edge 153 andfourth edge 154 is the longitudinal axis of thecooling chamber 130, which is illustrated as longitudinalaxis reference line 159 inFIG. 7 . In certain preferred embodiments, theangle 176 therib 135 defines with the longitudinalaxis reference line 159 of thecooling chamber 130 is between 0° and 60°. More preferably, theangle 176 defined between therib 135 and the longitudinalaxis reference line 159 of thecooling chamber 130 is between 0° and 30°. - As shown in
FIG. 7 , the coolant path defined by theswitchback 131 may be described as including: a) aninlet channel width 160, which represents the channel width of theswitchback 131 at theinlet 132, b) apre-turn channel width 161, which represents the channel width of theswitchback 131 between thesecond end 158 of therib 135 and thethird edge 153, c) apost-turn channel width 162, which represent the channel width of theswitchback 131 between thesecond end 158 of therib 135 and thefourth edge 154, and d) anoutlet channel width 163, which represents the channel width of theswitchback 131 path at theoutlet 134. The ever narrowing channel includes a configuration in which theinlet channel width 160 is greater than thepre-turn channel width 161, thepre-turn channel width 161 is greater than thepost-turn channel width 162, and thepost-turn width 162 is greater than theoutlet channel width 163. As further shown inFIG. 7 , between thepre-turn channel width 161 and thepost-turn channel width 162, theswitchback 131 includes the turn-section 142, within which a turn-section channel width 164 represents a channel width of theswitchback 131 between thesecond end 158 of therib 135 and thesecond edge 152 of thecooling chamber 130. According to an embodiment of the present application, the ever narrowing channel of theswitchback 131 includes a configuration in which the turn-section channel width 164 is less than thepre-turn channel width 161 and greater than thepost-turn channel width 162. The ever narrowing channel along both of the flanks of therib 135 may further be described as including: the channel width of theswitchback 131 decreasing at a constant linear rate between theinlet channel width 160 and thepre-turn channel width 161, and the channel width of theswitchback 131 decreasing at a constant linear rate between thepost-turn channel width 162 and theoutlet channel width 163. - As described, the cooling passages within turbine blades may be supplied with coolant in a variety of ways. Typically, cooling passages either receive coolant via internal passages that connect to a coolant source through the root of the blade or may be supplied with coolant through a connection with the shank cavity. Unless otherwise stated herein, the present application should not be limited to any specific method or configuration for delivering coolant to the
inlet 132 or removing coolant from theoutlet 134 of thecooling chamber 130. - It will be appreciated that turbine blades that are cooled via the internal circulation of a coolant typically include an
interior cooling passage 116 that extends radially outward from the root, through the platform region, and into the airfoil, as described above in relation to several conventional cooling designs. It will be further appreciated that certain preferred embodiments of the present invention may be used in conjunction with conventional coolant passages to enhance or enable efficient active platform cooling, and that aspects of the present invention may be discussed in connection with one common design, such as aninterior cooling passage 116 having a winding or serpentine configuration, though the aspect is not so limited in its application. As depicted in the figures, the serpentine path of theinterior cooling passage 116 is typically configured to allow a one-way flow of coolant and includes features that promote the exchange of heat between the coolant and thesurrounding airfoil 102. In operation, a pressurized coolant, which typically is compressed air bled from the compressor (though other types of coolant, such as steam, also may be used with embodiments of the present invention), is supplied to theinterior cooling passage 116 through a connection formed through theroot 104. The pressure drives the coolant through theinterior cooling passage 116, and the coolant convects heat from the surrounding walls. - As the coolant moves through the
cooling passage 116, it will be appreciated that it loses pressure, with the coolant in the upstream portions of theinterior cooling passage 116 having a higher pressure than coolant in downstream portions. As discussed in more detail below, this pressure differential may be used to drive coolant across or through cooling passages formed in the platform. It will be appreciated that the present invention may be used inrotor blades 100 having internal cooling passages of different configurations and is not limited to interior cooling passages having a serpentine form. Accordingly, as used herein, the term “interior cooling passage” or “cooling passage” is meant to include any passage or hollow channel through which coolant may be circulated in the rotor blade. As provided herein, theinterior cooling passage 116 of the present invention extends to at least to the approximate radial height of theplatform 116, and may include at least one region of relatively higher coolant pressure (which, hereinafter, is referred to as a “region of high pressure” and, in some cases, may be an upstream section within a serpentine passage) and at least one region of relatively lower coolant pressure (which, hereinafter, is referred to as a “region of low pressure” and, relative to the region of high pressure, may be a downstream section within a serpentine passage). - As illustrated in
FIGS. 9 and 10 , a high-pressure connector 171 may be configured to connect theinlet 132 to a high-pressure coolant region of theinterior cooling passage 116, and a low-pressure connector 172 may be configured to connect theoutlet 134 to a low-pressure coolant region of theinterior cooling passage 116. In operation, the pressure differential between the high-pressure region and the low-pressure region drives the coolant through thecooling chamber 130. That is, the high-pressure connector 171 extracts a portion of the coolant from theinterior cooling passage 116, which is used within thecooling chamber 130 to remove heat from theplatform 110 and then is returned via the low-pressure connector 172 to theinterior cooling passage 116 where is may be used further to cool the rotor blade. - In other cases, as illustrated in
FIG. 11 , theinlet 132 may be supplied with coolant via a connector to an interior cooling channel 116 (such as the high-pressure connector 171) while theoutlet 134 fluidly communicates with a plurality of film cooling ports orsurface ports 175 that are formed on the surface of theplatform 110. In one preferred embodiment, as illustrated, thesurface ports 175 are positioned along thepressure side slashface 126. In other embodiments, thesurface ports 175 may be positioned on thesuction side slashface 122. - The present application thereby describes a two pass serpentine or switchback coolant path for use in the platform of a turbine rotor blade that includes an angled or canted rib that promotes more evenly distributed cooling. Referring to
FIG. 12 , it will be appreciated that the canted rib creates a decreasing cross sectional coolant flow area as the flow distance through the coolant path increases. Specifically,FIG. 12 provides a graphical representation of “Flow Parameters” versus “Total Flow Distance Through Switchback”. As shown, the “Cross Sectional Flow Area” linearly decreases due to the canted rib. The decreasing coolant flow area causes the velocity of the coolant to increase, which causes the “Heat Transfer Coefficient” of the coolant to increase. This increase counters the loss in cooling effectiveness that stems from a rise in the “Coolant Temperature” that occurs as the coolant absorbs heat moving along the coolant path. This results in an approximately constant “Heat Transfer Coefficient” as the coolant moves from one end of the coolant path to the other, which promotes more even cooling through the platform, which discourages or prevents the development of hotspots that quicken degradation of the component. - More specifically, by angling the rib between the two passes of the switchback, the cross sectional area is constantly decreasing as the coolant flows through the path. Since the mass flow rate of the coolant is constant, the decreasing area must in turn create a greater velocity. Since duct flow heat transfer coefficients are greatly influenced by fluid velocity, this creates an increasing HTC as the fluid travels through the serpentine. It will be appreciated that, because the coolant is increasing in temperature as it travels along the switchback and picks up heat from the rotor blade, the coolant becomes less able to cool the downstream portions of a typical coolant path. However, the present application describes a way in which this loss of coolant effectiveness due to temperature rise may be offset (via the increase in heat transfer coefficient due to the increased velocity) so that a relatively constant heat transfer rate is maintained through the length of the coolant path, as opposed to a decreasing one. As one of ordinary skill in the art will appreciate, for lower flow applications where convection heat transfer coefficients are low, embodiments of the present application allow for greater heat transfer with the same amount of flow. This may allow the usage of a switchback core in certain low flow applications where before it could not due to flow limitations. In other applications, the flow rate can be reduced when changing from a constant cross sectional area core versus the proposed design since the flow is used more efficiently, which, in regard to turbine engines, translates into increases in engine efficiency. Another benefit is that, in some cases, turbulators can be eliminated, which produce undesirable high frictional losses in serpentine cores. In addition, the total area of the entire two pass switchback may be unchanged, with the only modification being the canting of the rib, which allows greater cooling without increasing the size of the coolant passages or amount of coolant.
- In an alternative, the above-described design features may be applied in similar fashion to the sidewall region of a stator rotor blade.
FIG. 13 illustrates a side view of a turbine stator blade showing the positioning of cooling configuration according to an alternative embodiment of the present invention; and -
FIG. 14 illustrates a top with partial cross-sectional view of a sidewall of aturbine stator blade 180 having a cooling configuration according to an alternative embodiment of the present invention. Thestator blade 180 may include an airfoil 182 that juts inboard from an attachment with the surrounding stationary structure of the turbine section of the combustion engine. At an inboard edge of the airfoil 182, stator blade 182 may include asidewall 184 that defines the inner radial edge of the working fluid flow path through the turbine. It will be appreciated that thesidewall 184 is similar in shape to theplatform 110 of therotor blade 100. Thesidewall 184 may include acooling chamber 130 having substantially the same features as discussed above. It will be appreciated that, as shown, the coolingchamber 130 of thesidewall 184 may have aninlet connector 185 that fluidly communicates with aninlet 132 of thecooling chamber 130, as well as anoutlet connector 186 that fluidly communicates with anoutlet 134 of thecooling chamber 130. The coolingchamber 130 of thesidewall 184 may have arib 135 that is angled or canted as discussed above, which may result in an ever-narrowing upstream 138 anddownstream pass 139. - As one of ordinary skill in the art will appreciate, the many varying features and configurations described above in relation to the several exemplary embodiments may be further selectively applied to form the other possible embodiments of the present invention. For the sake of brevity and taking into account the abilities of one of ordinary skill in the art, all of the possible iterations is not provided or discussed in detail, though all combinations and possible embodiments embraced by the several claims below or otherwise are intended to be part of the instant application. In addition, from the above description of several exemplary embodiments of the invention, those skilled in the art will perceive improvements, changes, and modifications. Such improvements, changes, and modifications within the skill of the art are also intended to be covered by the appended claims. Further, it should be apparent that the foregoing relates only to the described embodiments of the present application and that numerous changes and modifications may be made herein without departing from the spirit and scope of the application as defined by the following claims and the equivalents thereof.
Claims (21)
1. A cooling arrangement in one of a sidewall of a stator blade and a platform in a rotor blade in a turbine of a combustion turbine engine, the cooling arrangement comprising:
a cooling chamber configured to pass coolant from an inlet to an outlet; and
a rib positioned within the cooling chamber, the rib partially dividing the cooling chamber so to form a switchback;
wherein the rib is canted with respect to the cooling chamber such that the switchback comprises an ever narrowing channel.
2. The cooling arrangement according to claim 1 , wherein ever narrowing channel comprises a channel that narrows at a constant rate as the channel extends from the inlet to the outlet of the cooling chamber.
3. The cooling arrangement according to claim 1 , wherein the ever narrowing channel comprises a channel that narrows at a constant rate along both flanks of the rib.
4. The cooling arrangement according to claim 3 , wherein the switchback comprises a pass positioned on each flank of the rib: an upstream pass disposed on a flank of the rib that coincides with the inlet; and a downstream pass disposed on a flank of the rib that coincides with the outlet; and
wherein, between the upstream pass and the downstream pass, the switchback comprises a turn section that defines a turn of approximately 180°.
5. The cooling arrangement according to claim 4 , wherein the cooling chamber comprises a first edge and a second edge, wherein the second edge opposes the first edge across the cooling chamber;
wherein the rib extends linearly between a first end, which is positioned on the first edge of the cooling chamber between the inlet and outlet, and a second end, which is offset a distance from the second edge of the cooling chamber.
6. The cooling arrangement according to claim 5 , wherein:
the rib is canted such that: a channel width of the upstream pass decreases at a linear rate as the upstream pass extends from the inlet to the second end of the rib; and a channel width of the downstream pass decreases at a linear rate as the downstream pass extends from the second end of the rib to the outlet; and
a channel width of a downstream end of the upstream pass is just greater than a channel width of an upstream end of the downstream pass.
7. The cooling arrangement according to claim 1 , wherein the cooling chamber comprises a planar configuration and an outboard profile of a quadrilateral; and
wherein the rib is linear.
8. The cooling arrangement according to claim 7 , wherein the quadrilateral comprises a first pair and a second pair of opposing edges, each pair comprising two of the sides of the quadrilateral that oppose each other across the cooling chamber;
wherein the first pair of opposing edges includes a first edge and a second edge, and the second pair of opposing edges includes a third edge and a fourth edge; and
wherein the inlet and the outlet are disposed on the first edge, and, between the inlet and the outlet, a first end of the rib is positioned on the first edge.
9. The cooling arrangement according to claim 8 , wherein, from the first end, the rib extends toward the second edge, the rib terminating at a second end;
wherein the second end of the rib is offset a distance from the second edge.
wherein the third edge is parallel to the fourth edge; and
wherein the rib is canted with respect to a direction of a longitudinal axis of the cooling chamber that is defined by midpoints defined between the third and fourth edge.
10. The cooling arrangement according to claim 9 , wherein the rib is canted toward the third edge such that, as the rib extends from the first edge toward the second edge, a distance between the rib and the third edge decreases by a linear rate while a distance between the rib and the fourth edge increases by the linear rate.
11. The cooling arrangement according to claim 10 , wherein the angle defined between the rib and the direction of the longitudinal axis of the cooling chamber is between 0° and 30°.
12. The cooling arrangement according to claim 10 , wherein the angle defined between the rib and the longitudinal axis of the cooling chamber is between 0° and 60°;
wherein the switchback comprises: a) an inlet channel width, which represents the channel width of the switchback at the inlet; b) a pre-turn channel width, which represents the channel width of the switchback between the second end of the rib and the third edge; c) a post-turn channel width, which represent the channel width of the switchback between the second end of the rib and the fourth edge; and d) an outlet channel width, which represents the channel width of the switchback path at the outlet; and
wherein the ever narrowing channel comprises a configuration in which the inlet width is greater than the pre-turn width; the pre-turn width is greater than the post-turn width; and the post-turn width is greater than the outlet channel width.
13. The cooling arrangement according to claim 12 , wherein, between the pre-turn channel width and the post-turn channel width, the switchback comprises a turn-section within which a turn-section channel width represents a channel width of the switchback between the second end of the rib and the second edge of the cooling chamber;
wherein the ever narrowing channel comprises a configuration in which the turn-section channel width is less than the pre-turn channel width and greater than the post-turn channel width.
14. The cooling arrangement according to claim 12 , wherein the ever narrowing channel along both of the flanks of the rib comprises:
the channel width of the switchback decreasing at a constant linear rate between the inlet channel width and the pre-turn channel width; and
the channel width of the switchback decreasing at a constant linear rate between the post-turn channel width and the outlet channel width.
15. The cooling arrangement according to claim 9 , wherein the outboard profile of the cooling chamber comprises a parallelogram.
16. The cooling arrangement according to claim 9 , wherein the one of the platform and the sidewall comprises a planar configuration and wherein the cooling chamber comprises a planar configuration that is aligned with the planar configuration of the one of the platform and the sidewall and contained therein.
17. The cooling arrangement according to claim 9 , wherein the one of the platform and the sidewall comprises a planar topside;
wherein the cooling chamber comprises a planar ceiling that is just inboard of the topside and a planar floor radially offset from the ceiling, and
wherein a radial height of the cooling chamber comprises the radial offset between the ceiling and the floor; and
wherein the radial height of the cooling chamber is constant.
18. The cooling arrangement according to claim 9 , wherein the cooling arrangement is disposed in the platform of the rotor blade;
wherein the rotor blade includes an interior cooling passage formed therein that extends from a connection with a coolant source at the root to the approximate radial height of the platform, wherein, in operation, the interior cooling passage comprises a high-pressure coolant region and a low-pressure coolant region;
further comprising:
a high-pressure connector that connects the inlet to the high-pressure coolant region of the interior cooling passage;
a low-pressure connector that connects the outlet to the low-pressure coolant region of the interior cooling passage.
19. The cooling arrangement according to claim 9 , wherein the cooling arrangement is disposed in the platform of the rotor blade;
wherein the rotor blade includes an interior cooling passage formed therein that extends from a connection with a coolant source at the root to the approximate radial height of the platform;
further comprising:
a connector that connects the inlet to the interior cooling passage; and
a plurality of film cooling ports that fluidly communicate with the outlet.
20. A cooling arrangement in a platform of a rotor blade in a turbine of a combustion turbine engine, the cooling arrangement comprising:
a cooling chamber configured to pass coolant from an inlet to an outlet; and
a rib positioned within the cooling chamber, the rib partially dividing the cooling chamber so to form a switchback;
wherein the rib is canted with respect to the cooling chamber such that the switchback comprises an ever narrowing channel.
21. A cooling arrangement in a sidewall of a stator blade in a turbine of a combustion turbine engine, the cooling arrangement comprising:
a cooling chamber configured to pass coolant from an inlet to an outlet; and
a rib positioned within the cooling chamber, the rib partially dividing the cooling chamber so to form a switchback;
wherein the rib is canted with respect to the cooling chamber such that the switchback comprises an ever narrowing channel.
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US13/600,756 US20140064942A1 (en) | 2012-08-31 | 2012-08-31 | Turbine rotor blade platform cooling |
DE102013108984.4A DE102013108984A1 (en) | 2012-08-31 | 2013-08-20 | Cooling of a turbine blade platform |
JP2013171821A JP2014047782A (en) | 2012-08-31 | 2013-08-22 | Turbine rotor blade platform cooling |
CH01438/13A CH706961A2 (en) | 2012-08-31 | 2013-08-22 | Cooling a turbine blade. |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US13/600,756 US20140064942A1 (en) | 2012-08-31 | 2012-08-31 | Turbine rotor blade platform cooling |
Publications (1)
Publication Number | Publication Date |
---|---|
US20140064942A1 true US20140064942A1 (en) | 2014-03-06 |
Family
ID=50181865
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US13/600,756 Abandoned US20140064942A1 (en) | 2012-08-31 | 2012-08-31 | Turbine rotor blade platform cooling |
Country Status (4)
Country | Link |
---|---|
US (1) | US20140064942A1 (en) |
JP (1) | JP2014047782A (en) |
CH (1) | CH706961A2 (en) |
DE (1) | DE102013108984A1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2020046381A1 (en) * | 2018-08-31 | 2020-03-05 | Siemens Aktiengesellschaft | A method for manufacturing a heat transfer design for progressive heat transfer capability cooling channels |
WO2020046379A1 (en) * | 2018-08-31 | 2020-03-05 | Siemens Aktiengesellschaft | A heat transfer design for progressive heat transfer capability cooling channels |
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-
2012
- 2012-08-31 US US13/600,756 patent/US20140064942A1/en not_active Abandoned
-
2013
- 2013-08-20 DE DE102013108984.4A patent/DE102013108984A1/en not_active Withdrawn
- 2013-08-22 JP JP2013171821A patent/JP2014047782A/en active Pending
- 2013-08-22 CH CH01438/13A patent/CH706961A2/en not_active Application Discontinuation
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US4353679A (en) * | 1976-07-29 | 1982-10-12 | General Electric Company | Fluid-cooled element |
US4456428A (en) * | 1979-10-26 | 1984-06-26 | S.N.E.C.M.A. | Apparatus for cooling turbine blades |
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WO2020046381A1 (en) * | 2018-08-31 | 2020-03-05 | Siemens Aktiengesellschaft | A method for manufacturing a heat transfer design for progressive heat transfer capability cooling channels |
WO2020046379A1 (en) * | 2018-08-31 | 2020-03-05 | Siemens Aktiengesellschaft | A heat transfer design for progressive heat transfer capability cooling channels |
Also Published As
Publication number | Publication date |
---|---|
DE102013108984A1 (en) | 2014-03-20 |
CH706961A2 (en) | 2014-03-14 |
JP2014047782A (en) | 2014-03-17 |
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