EP3199759A1 - Turbine blade for a thermal turbo engine - Google Patents

Abstract

The invention relates to a turbine blade (10, 110, 210, 310) for a thermal turbomachine, comprising an airfoil (14), which can be flowed around by a hot gas, which has a suction side wall (22) and a pressure side side wall (20) in the main flow direction Hot gas is seen from a common leading edge to a common trailing edge (24) and along a longitudinal axis (12) substantially perpendicular to the main flow direction viewed from a first end of the airfoil (14) to a second end of the airfoil (14) opposite thereto. extend with a length, wherein in the blade inner side at least one cooling channel (28) is provided which is bounded by a plurality of inner surfaces (21, 23) and which has an access (34) through which a cooling medium (K) from outside the turbine blade (10 , 110, 210, 310) can be flowed into the cooling channel (28), wherein the turbine blade (10, 110, 210, 310) pulls ang (34) comprises a cover (36) having at least one opening (38). In order to make them efficiently coolable, it is proposed that the cover element (36, 136, 236, 336) comprises means which impart a twist to the cooling medium (K) which can flow into the cooling channel (28).

Description

The invention relates to a turbine blade for a thermal turbomachine, comprising an airfoil which can be flowed around by a hot gas and which has a suction-side sidewall and a pressure-side sidewall, the main flow direction of the hot gas being viewed from a common leading edge to a trailing edge and along a direction to the main flow direction Substantially perpendicular longitudinal axis extending from a first end of the airfoil to this opposite the second end of the airfoil, wherein in the airfoil interior at least one cooling channel is provided, which is bounded by a plurality of inner surfaces, of which at least one of the first side wall inner surface at least partially the inside of one of the two Is side walls, and having an access through which a cooling medium can be flowed from outside the turbine blade in the cooling passage, wherein the turbine blade at the entrance with a cover member mitinde st comprises an opening.

A corresponding turbine blade is for example from the WO 2009/153108 A2 known. In the known turbine vane, a throttle plate is provided at the entrance of the cooling air duct, which reduces the amount of cooling medium flowing into the interior of the turbine blade. In the known cover plate two holes are provided whose position appears optional.

Due to the optional positioning of the holes, however, flow losses and lower cooling performance can occur, which is undesirable. So far, however, this problem has not been considered, which is why the present invention should remedy this.

The object of the invention is therefore to provide a turbine blade whose cover plate enables improved cooling.

This object is achieved by a turbine blade according to claim 1, wherein advantageous embodiments are specified in the dependent claims.

According to the invention, it is provided that the covering element comprises means which impart a twist to the cooling medium which can be flowed into the cooling channel. The invention is based on the finding that by introducing an additional velocity component in the circumferential direction, a heat transfer increase based on a purely parralel to the longitudinal axis of the cooling channel flowing cooling medium is made possible, so that the cooling medium can efficiently cool the wall surrounding the cooling channel. This is referred to below as cyclone cooling.

In order to produce sufficient cooling already in the inflow region of the cooling channel, it is proposed that the metal sheets, which are generally formed as cover elements at an access of the cooling channel, have means for generating a twist of the cooling medium which can flow in the cooling channel.

According to a first advantageous embodiment, the cover element comprises a swirl generator, preferably in the form of a drum, as a means for generating a swirl, in which - based on a central axis of the swirl generator - at least one, preferably a plurality of tangentially oriented Einstrompassagen along the circumference of the swirl generator are provided distributed. Due to the tangentially oriented Einstrompassagen then flows from the outside (or from inside) into the swirl generator a cooling medium (or off), which cause a helical flow in the interior (or outside) of the swirl generator. The helical flow then flows in concentric circles around the neutral chord of the cooling channel, so that in said

Cooling channel, which adjoins the swirl generator, which can spread the swirling flow with an additional Geschindigkeitskomponente in the circumferential direction for heat transfer increase.

According to an alternative embodiment, the cover element can have, as a means for generating the swirl, guide elements which impress a flow component oriented in the circumferential direction to the cooling medium flowing through the openings. This also makes it possible to ensure a swirling flow inside the cooling channel.

More preferably, the cover may extend partially into the cooling channel. In this case, the cover member may preferably comprise a tubular portion in which impingement cooling holes are provided. According to this preferred embodiment variant, the wall surrounding the cooling duct can be cooled down upstream and can be cooled downstream by the swirling cooling, which can also be referred to as cyclone cooling.

Conveniently, the turbine blade may be formed both as a guide blade and as a blade. Formed as a blade, the cover is attached to an underside of the usually fir-tree or dovetail-shaped blade root.

Figur 1

eine erfindungsgemäße Turbinenschaufel, ausgestaltet als Leitschaufel in einer teilgeschnittenen perspektivischen Darstellung,

Figur 2

einen schematischen Längsschnitt durch eine Turbinenschaufel mit einem Kühlkanal und einem daran angeordneten Abdeckelement gemäß eines zweiten Ausführungsbeispiels,

Figur 3

einen Querschnitt durch einen Drallerzeuger gemäß Figur 2,

Figur 4

den schematischen Längsschnitt gemäß Figur 2 mit einem dritten Ausführungsbeispiel eines erfindungsgemäßen Abdeckelements,

Figur 5

den schematischen Längsschnitt gemäß Figur 2 mit einem vierten Ausführungsbeispiel eines erfindungsgemäßen Abdeckelements und

Figur 6

einen Querschnitt durch einen weiteren Drallerzeuger.

The above-described characteristics, features and advantages of the invention and the manner in which they are achieved are explained in more detail below with the description of the exemplary embodiments with reference to the attached figures. Here, the figures are shown only schematically, which in particular no limitation of the feasibility of the invention is the result. Show it:

FIG. 1

a turbine blade according to the invention, designed as a vane in a partially cutaway perspective view,

FIG. 2

FIG. 2 shows a schematic longitudinal section through a turbine blade with a cooling channel and a cover element arranged thereon according to a second exemplary embodiment, FIG.

FIG. 3

a cross section through a swirl generator according to FIG. 2 .

FIG. 4

the schematic longitudinal section according to FIG. 2 with a third embodiment of a cover element according to the invention,

FIG. 5

the schematic longitudinal section according to FIG. 2 with a fourth embodiment of a cover according to the invention and

FIG. 6

a cross section through another swirl generator.

In all figures, identical features are provided with the same reference numerals.

FIG. 1 shows a perspective view of a longitudinal section through a turbine blade 10. The turbine blade 10 comprises along a virtual longitudinal axis 12 successively a mounting portion 18, a platform 16 and an aerodynamically curved airfoil 14. The airfoil 14 includes two side walls 20, 22, of which the first pressure side (20) and the second suction side (22) is arranged. The side walls 20, 22 extend from a common in FIG. 1 Not shown leading edge to a common trailing edge 24. The blade 14 is - as the position of the cutting plane makes it clear - hollow. This cavity is also referred to as cooling channel 28 and has at least one access 34. The access 34 is located at the one of the two ends 32 of the airfoil 14th

Of the two ends of the airfoil, there is only one end in FIG. 1 shown.

When the turbine blade 10 is configured as a guide blade, as shown, the blade blade 14 usually has a transversely extending platform 16 at both of its ends 32. For blades with so-called shrouds this is also true. Solely freestanding turbine blades have a platform only at one of their two blade ends, wherein in a turbine free-standing vane rather untypical and freestanding rather blades are common. Common are freestanding blades. Relative to the installation position in an example axially through-flowable gas turbine is usually spoken of an inner platform and an outer platform, based on the machine axis of the gas turbine. Then also the longitudinal axis 12 is perpendicular to the machine axis. In the embodiment shown here, the platform 16 is arranged radially outward.

Although the access 34 is completely covered by a cover element 36 attached to the airfoil 14, it is only partially closed, since a plurality of openings 38 are provided in the cover element 36. The cover member 36 is secured to the remainder of the turbine bucket, the cast bucket body, in a conventional manner, such as by a welded joint.

When operating a gas turbine equipped with the illustrated turbine blade 10, the hot gas of the gas turbine flows from the leading edge to the trailing edge 24. In order for the airfoil 14 to withstand the hot temperatures, the airfoil 14 is internally cooled. For this purpose, the turbine blade 10 is supplied via the openings 38 cooling air, which along the cooling channel 28, the side walls 20, 22 flows cooling. from Cooling channel 28 from the cooling air flows through not shown further cooling channels to arranged at the trailing edge 24 outlet openings 40, at which the cooling air leaves the turbine blade 10.
In the exemplary embodiment shown, the outlet openings 40 are designed as so-called "cut-back openings". However, this is irrelevant to the invention. They could also alternatively be arranged as central outlet openings at the trailing edge 24.

According to a first embodiment of the invention, although the four openings 38 are designed as bores, their longitudinal axes do not extend perpendicular to the flat surface 37 of the cover 36. Rather, the bore axes of the openings 38 are inclined so that they each have a tangential component for the incoming Provide cooling medium K, so that in the cooling channel 28 can form a flow that is swirling: flowing in the cooling channel 28 cooling medium K flows quasi on one or more helical lines around the neutral chord of the cooling channel, which lies in the centroid of the cross section of the cooling channel.

Thus, as a means for generating a twist, the openings 38 are inclined relative to the Abdeckelementsenkrechten that they impose the incoming cooling medium K the swirl. Furthermore, in addition to or as an alternative to the inclined openings 38, guide elements may be provided on the surface of the cover element facing the cooling channel 28, which, for example, are inclined with respect to a surface perpendicular.

FIG. 2 shows the access-side region of the cooling channel 28 of an alternative turbine blade 110 in a further schematic representation. In analogy to the out FIG. 1 known turbine blade 10, the cooling channel 28 is bounded by inner surfaces 21, 23 which are part of the side walls 20 and 22 respectively. The access 34 of the cooling channel 28 is through a cover member 136 according to a second embodiment covered. The cover element 136 is configured in the shape of a cylinder hat and thereby has a collar-shaped ring 137, on whose inner diameter a swirl generator 139 is provided. The swirl generator 139 is in the form of a drum and in this embodiment does not extend into the cooling channel 28, but protrudes outwards. At the outer end of the swirl generator 139, a lid 140 is provided. In the collar-shaped ring 137 openings 138 are also provided.

FIG. 3 shows the cross section through the swirler 139 along the section line III-III. The swirl generator 139 is configured hollow inside and has an outer diameter d _a , which is comparatively large compared to its inner diameter d _i . As a result, the swirl generator 139 is made comparatively thick-walled. Through the wall of the swirl generator 139, two inflow passages 143, which are aligned tangentially with respect to a central axis 44 of the swirler 139, extend. Each inflow passage 143 may also be designed as a row of holes or as a slot.

In operation, the turbine blade 110 is supplied with the cooling medium K from outside. This flows laterally into the swirl generator 139 through the inflow passages 143. Due to the comparatively thick-walled design, the cooling medium K guided through the inflow passages 143 is directed into the interior of the swirl generator 139. This flows therein with a directed around the central axis 44 twist. Subsequently, the cooling medium flows into the cooling channel 28, where it continues to be swirling, where it cools the inner surfaces 21, 23 of the side walls 20, 22 and thus the blade 14.

• ein mittlere Kanalhöhe B_K als arithmetischer Mittelwert des minimalen und maximalen, zur Mittelachse senkrechten Abstands der beiden einander gegenüberliegenden Innenflächen 21, 23,
• eine axiale Länge H_S des Drallerzeuger 139, erfasst als axialer Abstand zwischen seinem Deckel 140 und dem kragenförmigen Ring 137,
• die Wandstärke WS des Abdeckelements 136,
• ein erster Abstand b₁ als projizierter (senkrechter) Abstand der Außenwand des Drallerzeugers 139 von den Innenflächen 21, 23,
• ein erster Durchmesser d₁ als Durchmesser derjenigen, im kragenförmigen Ring 137 angeordneten Öffnungen 138, die in Bezug auf die Mittelachse 44 - am weitesten außen angeordnet sind,
• ein zweiter Durchmesser d_x1 als Durchmesser derjenigen, im kragenförmigen Ring 137 angeordneten Öffnungen 138, die weiter innen - in Bezug auf die Mittelachse 44 - angeordnet sind,
• ein zweiter Abstand t₁ als Abstand zwischen der zu kühlenden Innenfläche 21, 23 und der Mitte der zuäußerst angeordneten Öffnung 138,
• ein dritter Abstand t_x1 als Abstand zwischen der zuäußerst angeordneten Öffnung 138 und der nächstinneren Öffnung 138,
• ein dritter Durchmesser d_a als äußerer Durchmesser des Drallerzeugers 139,
• ein vierter Durchmesser d_i als innerer Durchmesser des Drallerzeugers 139,
• eine Exzentrizität e als Abstand zwischen der Mittelachse 44 des Drallerzeugers 139 und der betreffenden Einströmpassage 143 und
• eine Einströmfläche A_In als Summe der Einströmquerschnitte aller Einströmpassagen 143.

As shown in FIGS. 2 and 3 are the arrangement according to the second embodiment of the cover 136 to take the following parameters:

• a mean channel height B _K as the arithmetic mean of the minimum and maximum distance, perpendicular to the central axis, of the two opposite inner surfaces 21, 23,
• an axial length H _{S of} the swirl generator 139, detected as an axial distance between its cover 140 and the collar-shaped ring 137,
• the wall thickness WS of the cover element 136,
• a first distance b ₁ as a projected (vertical) distance of the outer wall of the swirl generator 139 from the inner surfaces 21, 23,
• a first diameter d ₁ as the diameter of that in the collar-shaped ring 137 arranged openings 138, which are arranged with respect to the central axis 44 - outermost,
• a second diameter d _x1 as a diameter of those arranged in the collar-shaped ring 137 openings 138 which are further inwardly - with respect to the central axis 44 - are arranged
• a second distance t ₁ as the distance between the inner surface 21, 23 to be cooled and the center of the uppermost opening 138,
• a third distance t _x1 as a distance between the uppermost opening 138 and the next inner opening 138,
• a third diameter d _a as the outer diameter of the swirler 139,
• a fourth diameter d _i as the inner diameter of the swirler 139,
• an eccentricity e as a distance between the central axis 44 of the swirl generator 139 and the respective inflow passage 143 and
• an inflow area A _In as a sum of the inflow cross sections of all inflow passages 143.

Since usually the strength of the side walls 20, 22 predetermined due to structural mechanical requirements and also the curvature of the side walls 20, 22 through the aerodynamic Requirements for the airfoil 14 are predetermined, results for the mean channel height B _K a predetermined value.

Thus, the value for the average channel height B _K, for example, between 1 cm and 4 cm and for the wall thickness WS of the cover 136, for example, between 0.5 mm and 2 mm.

Investigations have shown that a turbine blade 10 with a pure cyclone cooling with mediocre cooling effect can be provided if the parameters have the following values or correspond to the following conditions: Tab. 1 General requirement for a turbine blade with cyclone cooling General requirements for cyclone cooling B _K set WS set A _in depending on the cooling mass flow d _i depending on the cooling mass flow e = 0.5 · d _i d _a ≤ 1 · B _K d ₁ ≤ (b ₂ - WS) t ₁ ≥ 0.5 · d ₁ d _xi ≤ (b ₂ - WS) t _xi ≥ 0.5 · dxi H _s depending on A _in b ₁ ≤ 0.15 · B _K

Of course, variants of cover elements 36 are also conceivable in which openings 138 are missing in the collar-shaped ring 137. This applies in particular to variants in which the first distance b _{1 is selected} to be zero. Likewise, the apertures 138 may be employed as well as the apertures 38 of the first embodiment to further aid in the cyclonic action of the vortex generator 139.

For a comparatively weakly cyclone-cooled turbine blade 110, their parameters should correspond to the values or conditions given in Table 2: Tab. 2 Example of a turbine blade with a weak cyclone cooling Weak cyclone cooling B _K set WS set A _in depending on the cooling mass flow d _i depending on the cooling mass flow e = 0.5 · d _i d _a ≤ 0.5 · B _K d ₁ = 1 mm t ₁ ≥ 0.5 · d ₁ + 1 · WS d _xi = 0 (only one row of openings) t _xi = 0 (only one row of openings) H _S = 5 · WS b ₁ = 0.15 · B _K

For a comparatively strongly cyclone-cooled turbine blade 110, the parameters should correspond to the values or conditions given in Table 3: Tab. 3 Example of a turbine blade with a strong cyclone cooling Strong cyclone cooling B _K set WS set A _in depending on the cooling mass flow d _i depending on the cooling mass flow e = 0.5 · d _i d _a ≤ 0.7 · B _K d ₁ ≤ 0.10 · B _K t ₁ ≥ 0.5 · d ₁ + 1 · WS d _xi <0.05 · B _K t _xi ≥ 1 · d _xi H _S = 8 · WS b ₁ = 0.25 · B _K

FIG. 4 shows a third turbine blade 210 with a third embodiment of a cover 236. However, only the differences from the second embodiment will be explained below.

The cover element 236 is designed in such a way that, in addition to cyclone cooling, it additionally effects a partial impingement cooling of the cooling channel or of the inner surfaces 21, 23 allows. For this purpose, the cover element 236 is formed as a shortened impingement cooling insert with a tubular section 245 compared to the length of the cooling channel. Impact cooling openings 247 are provided in the tubular section 245, wherein the tubular section 245 is preferably not circular in cross-section, but rather resembles the cross-sectional contour of the mostly trapezoidal cooling channel 28. Thus, the tubular portion 245 has an inflow-side end 34 with an opposing bottom 249. The swirl generator 139 is attached to the floor 249 via a support wall 251. In order to obtain a flat cover member 36, the tubular portion 245 and the swirl generator 139 overlap. In the bottom 249 and the swirl-supporting openings 38 are arranged.

Thus, during operation, the airfoil 14 is impingement-cooled in a first section D and cyclone-cooled in a second section M.

A fourth exemplary embodiment of a cover element 336 in the form of a combined impact-cooling insert with a swirl generator 339 is shown in FIG FIG. 5 illustrated in which the swirl generator 339 and the tubular portion 245 for the impingement cooling with respect to the longitudinal axis of the cooling channel 28, not as in FIG. 4 overlapping, but are arranged axially offset from each other.

Finally shows FIG. 6 an alternative swirl generator 339. The swirl generator 339 according to this embodiment comprises eight rectilinear inflow passages 343 arranged with respect to the center axis 44 and the third diameter d _a like a secant. Each inflow passage 343 may be configured as a single bore, as a series of holes or as a slot.

Due to the staggered arrangement of the swirl generator 339 in the reverse direction - in relation to the second embodiment - flows through. In that sense, the of the inner, fourth diameter d _i defined surface of the swirl generator 339 the inflow surface A _In for the cooling medium K.

• ein mittlere Kanalhöhe B_K als arithmetischer Mittelwert des minimalen und maximalen, zur Mittelachse senkrechten Abstands der beiden einander gegenüberliegenden Innenflächen 21, 23,
• eine axiale Länge H_s des Drallerzeuger 139,
• die Wandstärke WS des Abdeckelements 36,
• eine Exzentrizität e als Abstand zwischen der Mittelachse 44 des Drallerzeugers 339 und der betreffenden Einströmpassage 143 bzw. Ausströmpassage 343,
• ein dritter Durchmesser d_a als äußerer Durchmesser des Drallerzeugers 139,
• ein vierter Durchmesser d_i als innerer Durchmesser des Drallerzeugers 139,
• eine Einströmfläche A_In als Summe der Einströmquerschnitte aller Einströmpassagen 143 (nur für das dritte Ausführungsbeispiel) bzw. als Einströmquerschnitt des vierten Durchmessers d_i (nur für das vierte Ausführungsbeispiel),
• ein Durchmesser d der Prallkühlöffnungen 247,
• Prallkühllänge H des rohrförmigen Abschnitts 245, erfasst zwischen dem Zugang 34 und seinem Boden 249,
• ein vierter Abstand h₁ als Abstand zwischen dem Boden 249 und der daran nächstliegenden Reihe an Prallkühlöffnungen 247,
• ein fünfter Abstand h_xi als Abstand zwischen zwei Reihen von Prallkühlöffnungen 247 sowie
• ein sechster Abstand z als Abstand zwischen der Innenfläche 21, 23 und dem rohrförmigen Abschnitt 245,
• ein siebter Abstand b als projizierter (senkrechter) Abstand der Prallkühleinsatzes zur Tragwand 251,
• eine Länge h_s2 als axiale Länge der Tragwand 251 (nur für das dritte Ausführungsbeispiel) und
• eine Länge h_s3 als axiale Länge der Tragwand 351 (nur für das vierte Ausführungsbeispiel).

According to the representations of the FIGS. 4 and 5 the arrangements according to the second and third embodiment of the cover 236, 336, the following parameters are shown:

• a mean channel height B _K as the arithmetic mean of the minimum and maximum distance, perpendicular to the central axis, of the two opposite inner surfaces 21, 23,
• an axial length H _{s of} the swirler 139,
• the wall thickness WS of the cover element 36,
• an eccentricity e as a distance between the central axis 44 of the swirl generator 339 and the relevant inflow passage 143 or outflow passage 343,
• a third diameter d _a as the outer diameter of the swirler 139,
• a fourth diameter d _i as the inner diameter of the swirler 139,
• an inflow area A _In as a sum of the inflow cross sections of all inflow passages 143 (only for the third embodiment) or as an inflow cross section of the fourth diameter d _i (only for the fourth embodiment),
• a diameter d of the impingement cooling holes 247,
• Impact cooling length H of the tubular portion 245, captured between the access 34 and its bottom 249,
• a fourth distance h ₁ as the distance between the bottom 249 and the next row of impingement cooling openings 247,
• a fifth distance h _xi as the distance between two rows of impingement cooling holes 247 as well
• a sixth distance z as a distance between the inner surface 21, 23 and the tubular portion 245,
• a seventh distance b as a projected (vertical) distance of the impingement cooling insert to the support wall 251,
• a length h _s2 as the axial length of the support wall 251 (only for the third embodiment) and
• a length h _s3 as the axial length of the support wall 351 (only for the fourth embodiment).

Investigations have shown that a turbine blade 210, 310 can be provided with an impingement and cyclone cooling, if the parameters have the following values or correspond to the following conditions: Tab. 4 General requirement for turbine blades with cyclone and impingement cooling For the impingement cooling section D For the cyclone cooling section M WS set B _K set d 0.8 mm <d <1.6 mm A _in depending on the cooling mass flow H ≥ 2 · d H _S depending on A _in h ₁ > 1 · d b 0.15 · B _K ≤ b ₁ ≤ 0.25 · B _K h _xi ≥ 1 · d e = 0.5 · d _i z z / d <4.5 d _i depending on the cooling mass flow d _a ≤ 0.7 · B _K h _s2 0 _{≤h s2} ≤ (HH _s ) h _s3 0 ≤ h _s3 ≤ 2 · H

Investigations have shown that a turbine blade 210, 310 can be provided with comparatively weak impingement and cyclone cooling if the parameters have the following values or correspond to the following conditions: Tab. 5 Example of a turbine blade with a weak cyclone and impingement cooling For the impingement cooling section D For the cyclone cooling section M WS set B _K set d = 1.0 mm A _in depending on the cooling mass flow H = 3 d H _S depending on A _in h ₁ ≥ 1 · d b = 0.25 · B _K h _xi ≥ 0 (only one row) e = 0.5 · d _i z z / d <4.5 d _i depending on the cooling mass flow d _a ≤ 0.5 · B _K h _s2 = 0 h _s3 = 0

Investigations have shown that a turbine blade 210, 310 can be provided with comparatively strong impingement and cyclone cooling if the parameters have the following values or correspond to the following conditions: Tab. 6 Example of a turbine blade with a weak cyclone and impingement cooling For the impingement cooling section D For the cyclone cooling section M WS set B _K set d = 0.8 mm A _in depending on the cooling mass flow H = 10 d H _S depending on A _in h ₁ ≥ 1 d b = 0.15 · B _K h _xi ≥ 1 d e = 0.5 · d _i z z / d <1.5 d _i depending on the cooling mass flow d _a ≤ 0.7 · B _K h _s2 = HH _S h _s3 = 1.5 · H

Although some terms are used in the specification or claims in the singular or in conjunction with a number word, the scope of the invention for these terms should not be limited to the singular or the respective number word. Further, the words "a" and "an" are not to be understood as number words but as indefinite articles.

The embodiments serve to illustrate the invention and do not limit the invention to the combinations of features specified therein, not even with respect to functional features. In addition, suitable features of each embodiment may also be explicitly considered isolated, removed from one embodiment, incorporated into another embodiment to complement it and combined with any of the claims, as far as that combination can solve the objects underlying the invention. Other developments and embodiments of the invention will become apparent to those skilled in the art with reference to the dependent claims, which may also be combined with the embodiments illustrated below.

Claims (6)

Turbine blade (10, 110, 210, 310) for a thermal turbomachine,
with an airfoil (14) which can be flowed around by a hot gas,
which comprises a suction-side side wall (22) and a pressure-side side wall (20), viewed in the main flow direction of the hot gas from a common leading edge to a common trailing edge (24) and along a longitudinal axis (12) substantially perpendicular to the main flow direction a first end of the airfoil (14) extending to a second end of the airfoil (14) opposite thereto that has a length,
wherein in the blade inner side at least one cooling channel (28) is provided, which is bounded by a plurality of inner surfaces (21, 23) and which has an access (34) through which a cooling medium (K) from outside the turbine blade (10, 110, 210, 310) can be flowed into the cooling channel (28), wherein the turbine blade (10, 110, 210, 310) at the access (34) comprises a cover element (36) with at least one opening (38),
characterized in that
the cover element (36, 136, 236, 336) comprises means which impart a twist to the cooling medium (K) which can flow into the cooling channel (28). Turbine blade (10, 110, 210, 310) according to claim 1,
in which the cover element (36, 136, 236, 336) comprises a swirl generator (39, 139, 336) in the form of a drum as means for generating a swirl, in which - with respect to its central axis (44) - at least one tangentially oriented inflow passage (143) is provided. Turbine blade (10, 110, 210, 310) according to claim 2,
in which the cover element (136) is at least partially in the form of a hat-hat. Turbine blade (10, 110, 210, 310) according to claim 1 or 2,
in which the cover element has guide elements as a means for generating a twist. Turbine blade (10, 110, 210, 310) according to one of claims 1 to 4,
wherein the cover member (236, 336) extends partially into the cooling passage (28). Turbine blade (10, 110, 210, 310) according to claim 5,
wherein the cover member (236, 336) comprises a tubular portion (245) in which impingement cooling holes (247) are provided.

Images