Turbine blade with pedestals and coolant flow passages in a cavity

Abstract

A turbine blade (10) comprising an inner skin (11) having a plurality of inlet through-holes (12), an outer skin (13) having a plurality of outlet through-holes (14), wherein the inner skin and the outer skin define a cavity (6) therebetween, a plurality of pedestals (15) located in the cavity and bridging the inner skin and the outer skin, wherein the plurality of pedestals (15) is arranged to define a plurality of passages (16) and a plurality of vortex generation zones (17) in the cavity, wherein each passage is positioned to direct coolant flow from an inlet through-hole (12) towards at least one vortex generation zone, and each vortex generation zone is substantially centred on an outlet through-hole (14).

Description

[0001] TURBINE BLADE

[0002] BACKGROUND

[0003] The present invention relates to a turbine blade, and in particular a turbine blade for a gas turbine engine such as a jet engine.

[0004] In a gas turbine engine, several stages of turbines are provided after a combustor. In general, in order to minimise the specific fuel consumption of the engine, the temperature of the gas entering the turbine (also known as the turbine entry temperature, TET) is set to be high as possible. In modem gas turbine engines, the TET may be as high as 1850K, which is higher than the limit at which the materials from which the turbine blades are typically made can operate (and indeed is typically higher than the melting point of the material from which the blades are made).

[0005] Thus, in order to allow the turbine to operate, a coolant is provided to the turbine blade. Typically, a system of internal passageways in the engine feeds coolant gas (i.e. air which enters the engine) from the compressor (where the temperature is significantly lower) to the interior of the turbine blades. This coolant gas is used in two ways. First, the coolant gas may remove heat from the blades by convection (from the surface of the blade to the coolant in the interior cavity of the blade), and may also be ejected from the interior of the blade so as to provide a shielding film around the external blade surfaces.

[0006] In some known arrangements, and as illustrated in figures 1 and 2, the interior cavity of the turbine blade may be provided with a plurality of pedestals, which provide heat transfer from the external surface of the blade to the coolant flowing around the pedestals, and also act to control the blowing rate of coolant into the mainstream flow (i.e. the flow around the blade), by restricting the passage of the coolant in the cavity and causing turbulence in the flow around the pedestals.

[0007] However, a large number of pedestals may be required in order to effectively control the blowing rate, which may be expensive and difficult to manufacture. Further, the small size ofholes which are needed in order to effectively control the blowing rate may mean that particles suspended in the coolant flow may block the holes, reducing cooling efficiency. Further, the coolant flow entering the interior cavity is directed at the inner surface of the hot outer wall of the turbine blade, which may cause suspended particles to adhere to the surface, which again may reduce cooling efficiency.

[0008] It is an aim of the present invention to at least partially address the problems noted above.

[0009] SUMMARY OF THE INVENTION

[0010] According to a first aspect, there is provided a turbine blade comprising an inner skin having a plurality of inlet through-holes, an outer skin having a plurality of outlet through-holes, wherein the inner skin and the outer skin define a cavity therebetween, and a plurality of pedestals located in the cavity and bridging the inner skin and the outer skin, wherein the plurality of pedestals is arranged to define a plurality of passages and a plurality of vortex generation zones in the cavity, wherein each passage is positioned to direct coolant flow from an inlet through-hole towards at least one vortex generation zone, and each vortex generation zone is substantially centred on an outlet through-hole.

[0011] Optionally, said vortex generation zones are each bounded by a respective wall of at least two different pedestals.

[0012] Optionally, said vortex generation zones are each bounded by a respective wall of four different pedestals.

[0013] Optionally, at least one of said pedestals includes a first wall bounding a first vortex generation zone, and a second wall bounding a second vortex generation zone.

[0014] Optionally, at least one of said passages is bounded by a respective wall of at least two different pedestals.Optionally, said at least one passage is bounded by a respective wall of two adjacent pedestals.

[0015] Optionally, said respective walls extend parallel to each other.

[0016] Optionally, said respective walls are positioned adjacent a respective inlet through-hole.

[0017] Optionally, at least one of said passages is configured to direct flow tangentially with respect to at least one vortex generation zone.

[0018] Optionally, at least one of said passages is configured to direct coolant flow towards a plurality of said vortex generation zones.

[0019] Optionally, at least one of said passages reduces in flow path area with increasing distance from a respective inlet through-hole.

[0020] Optionally, at least one of said pedestals is configured to split an oncoming coolant flow such that the coolant flow is directed to two adjacent vortex generation zones.

[0021] Optionally, said at least one pedestal includes two adjacent surfaces configured to split the oncoming coolant flow.

[0022] Optionally, at least one of said vortex generation zones is circular in cross-section.

[0023] Optionally, at least one of said vortex zones is quadrilateral in cross-section.

[0024] Optionally, said vortex generation zones are distributed in a spanwise direction in the cavity.

[0025] Optionally, said vortex generation zones are distributed in a chordwise direction in the cavity.

[0026] Optionally, at least one of said pedestals is curvilinear triangles in cross-section.Optionally, said curvilinear triangle has two concave curved sides and one straight side.

[0027] Optionally, said curvilinear triangle has three concave curved sides.

[0028] Optionally, at least one of said pedestals includes a first rectangular portion and a second rectangular portion in cross-section, the first and second rectangular portions adjoining each other with a right angle or an acute angle therebetween.

[0029] Optionally, at least one of said pedestals is L-shaped in cross-section.

[0030] The turbine blade optionally further comprises an outlet configured to exhaust suspended particles from the coolant flow, the outlet being positioned in a radially outer wall of the blade.

[0031] Optionally, the inlet through-holes are configured to receive a coolant flow from a coolant flow supply.

[0032] Optionally, the outlet through-holes are configured to eject coolant to provide a film over an outer surface of the outer skin.

[0033] According to a second aspect, there is provided a gas turbine engine comprising the blade as described above.

[0034] BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will now be described, by way of non-limitative example only, with reference to the accompanying drawings, in which:

[0036] Figure 1 shows a partial cutaway view of a known turbine blade;

[0037] Figure 2 shows a partial cutaway view of a further known turbine blade;

[0038] Figure 3 shows a partially cutaway perspective view of a turbine blade according to the present invention;Figure 4 shows a plan view of the arrangement of figure 3;

[0039] Figure 5 shows an enlarged view of the arrangement of figure 4;

[0040] Figure 6 shows a partial view of the arrangement of figures 3 and 4;

[0041] Figure 7 shows a partial view of a further arrangement of turbine blade according to the present invention;

[0042] Figure 8 shows a plan view cutaway section of a further arrangement of turbine blade according to the present invention;

[0043] Figure 9 shows a plan view cutaway section of a further arrangement of turbine blade according to the present invention;

[0044] Figure 10 shows a plan view cutaway section of a further arrangement of turbine blade according to the present invention;

[0045] Figure 11 shows particle tracks in the flow between two adjacent vortices in the arrangement of figure 3; and

[0046] Figure 12 shows particle tracks in the flow between two adjacent vortices in the arrangement of figure 9.

[0047] DETAILED DESCRIPTION

[0048] Figures 1 and 2 depict known arrangements of turbine blade of the type described above as background to the present invention.

[0049] Figure 1 depicts a known turbine blade with an inner skin 1, a plurality of inlet through-holes 2, an outer skin 3, and a plurality of outlet through-holes 4. A cavity 6 is formed between the inner skin 1 and the outer skin 3. The inlet through-holes 2 receive a coolant flow from a coolant flow supply. The coolant may be supplied from the interior of the blade, for example from a further cavity located inward of the inner skin 1 (and thus inward of cavity 6 formed between the inner skin 1 and the outer skin 3.

[0050] A plurality of pedestals 5 are located in the cavity 6. These pedestals may provide heat transfer from the hot gas flowing around the outer skin 3 to the coolant flowing around the pedestals. The pedestals may also restrict the coolant flow in the cavity, thus controlling the blowing rate of coolant through the outlet through-holes 4. However, the arrangement ofpedestals 5 is such that no vortex is formed centred on the outlet through-holes 4, because the pedestals are not positioned so as to direct the flow to form such a vortex.

[0051] Figure 2 depicts a partial sectional view of a further arrangement of known turbine blade, showing only the outer skin 3, the outlet through-holes 4 and the pedestals 5. The pedestals 5 are square in cross section, and are distributed so as to restrict the passage of the coolant throughout the cavity. However, the arrangement of pedestals 5 is such that no vortex is formed centred on the outlet through-holes 4, because the pedestals are not positioned so as to direct the flow to form such a vortex.

[0052] An arrangement of turbine blade according to the present invention is shown in figure 3.

[0053] The turbine blade 10 includes an inner skin 11 and an outer skin 12. The inner skin 11 and the outer skin 12 define a cavity therebetween. The blade is therefore a dual skin blade.

[0054] It will be understood that further features may be provided in the blade interior, and thus the inner skin may not be the innermost structure in the interior of the blade. For example, the inner skin 11 and the outer skin 12 may form a cavity therebetween, with a cavity acting as an outer cavity, and a further cavity may be defined inward of the inner skin 11 (similarly to the arrangement of cavities shown in figure 1).

[0055] The inner skin 11 includes a plurality of inlet through-holes 12, which may also be known as impingement holes. The inlet through-holes 12 may be configured to receive a coolant flow from a coolant flow supply. The coolant flow may be supplied from elsewhere in the turbine blade. For example, in some arrangements, the coolant may be supplied through the root of the blade (e.g. through an opening to a passage in the root of the blade, supplied through the hub of the turbine), and / or may be supplied to the inlet through-holes from (for example) a further cavity located inward of the cavity defined between the inner and outer skin.

[0056] The outer skin 13 includes a plurality of outlet through-holes 14, which may also be known as film holes. The outlet through-holes 14 may be configured to eject coolant to provide a film over an outer surface of the outer skin. That is, coolant flow may exit the cavity through theoutlet through-holes 14, and subsequently form a film around the blade, which may protect the blade from the hot gas surrounding it, which as described above may be at a temperature higher than the blade material can otherwise operate.

[0057] The blade further comprises a plurality of pedestals 15. The term “pedestal” is used to denote the members disposed in the cavity. The pedestals can also be considered as being heat transfer members and / or coolant flow restriction members and / or coolant flow redirectopm members.

[0058] The pedestals 15, as described above in relation to known arrangements extend between the inner skin 11 and the outer skin 12. That is, the pedestals 15 extend across the cavity in the thickness direction of the turbine blade. The pedestals 15 may be joined to the inner skin 11 and extend towards (and may also abut but not be joined to) the the outer skin 12.

[0059] Alternatively, the pedestals 15 may be formed as part of the outer skin 12 and extend towards (and may also abut but not be j oined to) the the inner skin 11. It will be understood that the pedestals 15 need not be joined to both the inner and the outer skin. The pedestals 15 may be integrally formed with the skin to which they are attached, or may be separately formed and subsequently attached to the skin.

[0060] The pedestals 15 may provide heat transfer from the outer skin 13 to the coolant flowing around the pedestals 15. It will be understood that the pedestals may be present in a portion of the cavity which is between the inner skin and the portion of the outer skin which corresponds to the suction surface of the turbine blade (i.e. the cutaway area in figure 3) and / or a portion of the cavity which is between the inner skin and the portion of the outer skin which corresponds to the pressure surface of the turbine blade.

[0061] Figures 4 and 5 depict the flow pattern of the coolant in the arrangement of figure 3, relative to the pedestals 15, and the passages 16 and vortex generation zones 17 defined by the pedestals. Although the shape of the pedestals 15 in figure 5 differs slightly from that depicted in figure 4, it will be understood that figure 5 is schematic, and depicts pedestals which share similar features to those shown in figures 3, 4 and 6 and function in a substantially similar manner.As shown in, for example, figures 4 and 5, the pedestals 15 are arranged so as to define a plurality of passages 16 and a plurality of vortex generation zones 17.

[0062] The passages 16 are positioned to direct coolant flow from the inlet through-holes towards the vortex generation zones. That is, the passages may provide a restricted flow area which guides the flow towards the vortex generation zones. This causes a vortex of coolant flow to be formed in the vortex generation zones. The passages 16 may in particular guide the coolant flow towards (i.e. increase the flow velocity in a direction of) the vortex generation zones 17 tangentially with respect to the vortex generation zones (and thus the vortices themselves). This may aid in strengthening the vortices.

[0063] The vortex generation zones 17 (and thus the vortices themselves) are centred on the outlet through-holes 14. In other words, the vortex generation zones 17 are areas in which a vortex is formed, bounded by one or more pedestals and with flow directed thereto by one or more pedestals. The interaction of the coolant flow with the pedestals may induce swirl in the flow, thus causing the formation of the vortex. The vortices themselves may restrict the coolant flow through the outlet through-holes 14, thus controlling the blowing rate of coolant through the outlet through-holes 14.

[0064] In other words, coolant flow enters the cavity through the inlet through-holes 12, is directed by the pedestals 15 to the vortex generation zones 17 (where it enters / forms the vortex), and exits the cavity through the outlet through-holes 14. The coolant flow is depicted by the arrows in figures 4 and 5. In particular, the arrows depict the movement of coolant flow from the passages to vortex generation zones (and the vortical movement of the coolant flow).

[0065] In some arrangements, the vortex generation zones may be bounded by a wall of at least two different pedestals. For example, in the arrangement shown in figure 4, the vortex generation zones 17 are bounded by a wall of four different pedestals. For example, vortex generation zone 17a is bounded by a wall of each of pedestals 15a, 15b, 15c and 15d. It will be understood that the term “bounded” means that the walls surround the respective vortexgeneration zone, but need not completely encircle the vortex generation zone. That is, the walls may partially surround the vortex generation zone and have gaps therebetween.

[0066] In some arrangements, a pedestal may bound more than one vortex generation zone. For example, in the arrangement of figure 4, pedestal 15c bounds both vortex generation zone 17a and vortex generation zone 17b. In other words, one wall of pedestal 15c bounds vortex generation zone 17a, and another wall of pedestal 15c bounds vortex generation zone 17b.

[0067] In some arrangements, the passages are also bounded by a wall of more than one pedestal. For example, in the arrangement of figure 4, passage 16 is bounded by a wall of pedestal 15b, and a wall of pedestal 15e. In this arrangement, the walls are of two adjacent pedestals.

[0068] These walls may also extend parallel to each other, as in the arrangement of figure 4. Further, in these arrangements, the walls of pedestals 15b and 15e are positioned adjacent the inlet through-hole 12b. This may allow flow to be directed from the inlet through-hole 12b along the passage and towards the respective vortex generation zone or zones.

[0069] In some arrangements, the passages are configured to direct coolant flow towards a plurality of vortex generation zones. For example, in the arrangement of figures 4 and 5, passage 16 directs flow towards both vortex generation zone 17a and vortex generation zone 17b. In this arrangement, the coolant flow is directed by a single passage to two adjacent vortex generation zones.

[0070] In some arrangements, oncoming flow which has passed through an inlet through-hole and a passage is split by a pedestal into two separate flows, each of which is directed to a separate vortex generation zone. For example, in the arrangement of figure 4, the flow from inlet hole 12b and passage 16 is split by pedestal 15c so as to be split between vortex generation zone 17a and vortex generation zone 17b. This splitting is done by adjacent surfaces of the pedestal, which meet at a point where the flow divides. It will be noted that in the arrangements of figures 4 and 5, adjacent vortices rotate in opposite directions. This may be a consequence of the flow from an inlet through- hole and passage being split either side of a pedestal, thus inducing vorticity (i.e. swirl) in opposite directions for each portion of the flow.In some arrangements, the vortex generation zones may be circular in cross-section. For example, in figure 4, the surfaces of the pedestals which bound the vortex generation zones are curved, such that they define vortex generation zones which are circular in cross-section. It will be appreciated that a vortex zone which is circular in cross-section corresponds to the vortex zone being cylindrical in three dimensions.

[0071] The pedestals 15 may be arranged so as to form a pattern, which may be a repeating pattern. Figure 4 is an example of such an arrangement. The pattern of pedestals (and thus the pattern of passages and vortex generation zones) may extend in one or more directions in the cavity The vortex generation zones may thus be distributed in a chordwise direction in the cavity, in a spanwise direction in the cavity, or in both a span-wise and chord-wise direction in the cavity (thus providing a chequerboard pattern of vortex zones). In other words, there is a plane of symmetry defined by the centre of the inlet through-holes and the location of the pedestals where the flow is split, with each vortex generation zone being symmetric to its neighbours in four directions.

[0072] In the arrangement of figure 4, the pedestals are curvilinear triangles in cross-section. That is, the pedestals in cross-section (in a plane substantially parallel to the blade surface) (are three sided shapes having one straight (i.e. linear) side, and two curved (i.e. arcuate) sides. Such a shape may provide the flow splitting properties described above as well as the shape of the vortex generation zones described above.

[0073] Figure 6 depicts a partial section of the blade shown in figures 3 and 4. It will be understood that this view shows only the outer skin 13, the outlet through-holes 14 and the pedestals 15. Again, the shape of the pedestals and the positional relationship between the vortex generation zones and the through-holes 14 can be seen, with the outlet through-holes 14 being centred in the vortex generation zones.

[0074] Figures 7-10 depict further arrangements with differing shapes of pedestals. It will be understood that all of the features described above in relation to figures 3-6 may apply equally to the arrangements of figures 7-10 (and vice versa), unless stated otherwise.Figure 7 depicts a further arrangement of outer skin 13, outlet through-holes 14 and pedestals 15, in the same orientation as the view of figure 6. It will be understood that the positional relationship between the inlet holes is not depicted in figure 7, but will be described below in relation to figure 8, which depicts schematically the coolant flow in the arrangement of figure 7.

[0075] In the arrangements of figures 7 and 8, unlike the arrangements of figures 3-6, the pedestals 15 are not curvilinear triangles. Rather, the pedestals include a first rectangular portion and a second rectangular portion in cross-section, the first and second rectangular portions adjoining each other with a right angle or an acute angle therebetween. In the case of figures 7 and 8, the pedestals are L-shaped in cross-section (i.e. have the portions described above, with a right angle therebetween). However, it will be understood that other arrangements are possible in which the angle between the portions is less than a right angle, which may be considered to be an “arrowhead” shape in cross-section.

[0076] The flow patterns in the arrangement of figure 7 are shown in figure 8. Unlike the arrangement of figures 3-6, the vortex generation zones are quadrilateral in cross-section. This is due to the straight sides of the pedestals 15. It will be appreciated that a vortex zone which is circular in quadrilateral in cross-section corresponds to the vortex zone being cuboidal in three dimensions. In such arrangements, the vortex itself may nonetheless be cylindrical (i.e. circular in cross-section), but bounded by parts which are quadrilateral in cross-section.

[0077] Further, in the arrangement of figures 7 and 8, unlike the arrangement of figures 3-6, the passages are not formed between two parallel surfaces. Rather, they are formed in the space between the inside of the L-shaped pedestals. It will be noted from figure 8 that the width of the passages (and thus the coolant flow path area) reduces with increasing distance from the inlet through-holes 12. That is, a portion of the flow path area in the passages is smaller at a location further from the inlet through-holes than the flow path area adjacent the inlet through-holes. This may aid in accelerating flow towards the vortex generation zones 17.In the arrangement of figure 9, the pedestals 15 take the form of curvilinear triangles.

[0078] However, unlike the earlier arrangements, these curvilinear triangles include three curved (i.e. concave arcuate) sides. As shown in figure 9, the passages are circular in cross-section rather than linear slots. Again, similarly to the arrangement of figures 7 and 8, this may provide a reduction in flow area away from the inlet holes (and thus towards the vortex generation zones), which may result in flow being accelerated towards the vortex generation zones 17.

[0079] A further arrangement of pedestals is depicted in figure 10. In this arrangement, the pedestals 15 are circular in cross-section. In this arrangement, the passages are formed by a small region defined between adjacent circular pedestals 15.

[0080] The arrangements of the present invention may provide the advantages that fewer pedestals are required than in the known arrangements depicted in figures 1 and 2 (as can be seen in the contrast between figure 2 and figures 6 or 7, for example). This may reduce manufacturing complexity and / or cost.

[0081] Further, the formation of vortices centred on the outlet through-holes may provide improved control over the blowing ratio of coolant exiting into the film surrounding the blade. This may in turn provide improved control over cooling.

[0082] Further still, the use of vortices may allow the size of the inlet and / or outlet through-holes to be increased compared to known arrangements (such as those in figures 1 and 2) where the blowing ratio is controlled by the size of the holes. This may reduce the likelihood of the holes becoming blocked by particles suspended in the coolant flow. Likewise, larger outlet through-holes may mean that a larger proportion of the blade surface has holes, which may in turn improve the film cooling of the blade. Larger inlet through-holes may also lower the flow velocity through the inlet through-holes, which may in turn reduce the extent to which particles suspended in the coolant flow adhere to the inside surface of the inner skin.

[0083] Although in some known arragements, some vorticity may be induced in the flow due to the presence of pedestals in the cavity through which the coolant flows, such a small amount of induced vorticity (which is typically randomly distributed) does not result in a vortex zonecentred on the outlet through-holes, nor does it provide the advantages of the present invention set out above. This difference can be understood by considering the swirl in the coolant flow. The coolant flow in the arrangements of the present invention has significantly higher swirl than that in known arrangements. The swirl can be quantified by considering the swirl number, which is a dimensionless quantity defined as follows:

[0084] 5 = —

[0085]

[0086] GXR

[0087] Where G0is the inflow angular momentum, Gxis the momentum through the film hole, and R is a characteristic size (e.g. the hole radius). The arrangements of the present invention typically have a swirl number of approximately 12-20, whereas the known arrangements described above in the background to the invention would typically have a swirl number which is an order of magnitude less than those of the present invention (and may have a swirl number of 2 at the most) .

[0088] In the arrangements of the present invention, the flow in adjacent vortex generation zones may cross over between vortex generation zones, by virtue of the zones being in fluid communication with each other. An example of this is shown in figure 11, which depicts particle tracks for particles suspended in the coolant flow (and thus also provides a visualisation of the flow itself) for two adjacent vortex generation zones 17. The presence of the vortex may prevent particles from approaching the exit through-hole. Thus, when there are suspended particles (e.g. of dust or dirt) in the coolant flow, the particles may migrate between adjacent vortex generation zones. For example, in the arrangement hsown in figure 11, particles may enter vortex generation zone 17a as shown by arrow A, migrate to vortex generation zone 17b, and exit vortex generation zone 17b as shown by arrow B.

[0089] It will be understood that particles may move between a chain of more than two vortex generation zones in this way. This particle migration may be generally towards the radially outer portion of the blade, due to the centripetal acceleration caused by the rotation of the blade. Thus, particles may migrate towards the radially outer section of the blade. In some arrangements, these particles where they may be exhausted through a scavenge outlet (which may be an opening configured to exaust the particles). Such a scavenge outlet may be in the radially outer portion of the blade, such as the region labelled “S” in figure 11.A similar principle to that described above in relation to figure 11 is depicted in figure 12, which schematically shows particle tracks in an arrangement similar to that shown in figure 9. The coolant flow is depicted (in a similar manner to figure 9) by solid arrows C. The movement of particles suspended in the coolant flow is depicted by dashed arrows P. The direction of the centripetal acceleration caused by the rotation of the blade is shown by arrow A. It will be noted that (as shown by dashed arrows P) the particles migrate between adjacent vortex generation zones. In other words, the particles do not follow the coolant flow, but instead slip from the coolant flow and stay in the outer periphery of the vortex generation zones (and of the vortices themselves).

[0090] Due to the inertial force on the particles caused by their rotation in the vortex around the outlet through-hole, which throws the particles outwards, outweighing the radial drag force pulling the particles towards the outlet through-hole, there is a radius in each vortex zone that the particles are not able to move closer to the centre of the vortex (i.e. the outlet through-hole). This radius is depicted by dashed circles D in figure 12. Although this radius varies with particle size (and larger particles may stay at a larger radius from the centre of the vortex), the relative dimensions of the vortex generation zones and the outlet through-holes may be chosen such that particles which are of a size which could block the holes do not approach the holes closely enough to become entrained in the flow out of the hole (and thus block the hole). In other words, the particles are centrifuged outwards and migrate between vortex generation zones, rather than moving towards the centres of the vortex generation zones.

[0091] Although various arrangements of pedestals are described above and illustrated in the drawings, it will be understood that arrangements are possible in which different shapes of pedestals are combined in a single cavity. Likewise, in any of the above arrangements, some, but not all, of the pedestals (and thus some, but not all, of the passages and / or vortex generation zones) may have the features described above.

[0092] Although in the above, the turbine blade as disclosed herein is described in the context of a jet engine (e.g. an aircraft engine), it will be understood that such turbine blades can also be usedin other applications, such as ground-based gas turbines (e.g. as used in electricity generation).

[0093] It should be understood by those skilled in the art that while the present invention has been described with reference to exemplary embodiments, it is not limited to the disclosed exemplary embodiments. Various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof. Features from any example or embodiment of the present disclosure can be combined with features from any other example or embodiment of the present disclosure.

Claims

CLAIMS1. A turbine blade comprising:an inner skin having a plurality of inlet through-holes;an outer skin having a plurality of outlet through-holes, wherein the inner skin and the outer skin define a cavity therebetween; anda plurality of pedestals located in the cavity and bridging the inner skin and the outer skin;wherein the plurality of pedestals is arranged to define a plurality of passages and a plurality of vortex generation zones in the cavity, wherein each passage is positioned to direct coolant flow from an inlet through-hole towards at least one vortex generation zone, and each vortex generation zone is substantially centred on an outlet through-hole.

2. The turbine blade of claim 1, wherein said vortex generation zones are each bounded by a respective wall of at least two different pedestals.

3. The turbine blade of claim 2, wherein said vortex generation zones are each bounded by a respective wall of four different pedestals.

4. The turbine blade of claim 1, 2 or 3, wherein at least one of said pedestals includes a first wall bounding a first vortex generation zone, and a second wall bounding a second vortex generation zone.

5. The turbine blade of any preceding claim, wherein at least one of said passages is bounded by a respective wall of at least two different pedestals.

6. The turbine blade of any preceding claim, wherein said at least one passage is bounded by a respective wall of two adjacent pedestals.

7. The turbine blade of claim 5 or 6, wherein said respective walls extend parallel to each other.

8. The turbine blade of any of claims 5-7, wherein said respective walls are positioned adjacent a respective inlet through-hole.

9. The turbine blade of any preceding claim, wherein at least one of said passages is configured to direct flow tangentially with respect to at least one vortex generation zone.

10. The turbine blade of any preceding claim, wherein at least one of said passages is configured to direct coolant flow towards a plurality of said vortex generation zones.

11. The turbine blade of any preceding claim, wherein at least one of said passages reduces in flow path area with increasing distance from a respective inlet through-hole.

12. The turbine blade of any preceding claim, wherein at least one of said pedestals is configured to split an oncoming coolant flow such that the coolant flow is directed to two adjacent vortex generation zones.

13. The turbine blade of claim 12, wherein said at least one pedestal includes two adjacent surfaces configured to split the oncoming coolant flow.

14. The turbine blade of any preceding claim, wherein at least one of said vortex generation zones is circular in cross-section.

15. The turbine blade of any preceding claim, wherein at least one of said vortex zones is quadrilateral in cross-section.

16. The turbine blade of any preceding claim, wherein said vortex generation zones are distributed in a spanwise direction in the cavity.

17. The turbine blade of any preceding claim, wherein said vortex generation zones are distributed in a chordwise direction in the cavity.

18. The turbine blade of any preceding claim, wherein at least one of said pedestals is curvilinear triangles in cross-section.

19. The turbine blade of claim 18, wherein said curvilinear triangle has two concave curved sides and one straight side.

20. The turbine blade of claim 18, wherein said curvilinear triangle has three concave curved sides.

21. The turbine blade of any preceding claim, wherein at least one of said pedestals includes a first rectangular portion and a second rectangular portion in cross-section, the first and second rectangular portions adjoining each other with a right angle or an acute angle therebetween.

22. The turbine blade of any preceding claim, wherein at least one of said pedestals is L-shaped in cross-section.

23. The turbine blade of any preceding claim, further comprising an outlet configured to exhaust suspended particles from the coolant flow, the outlet being positioned in a radially outer wall of the blade.

24. The turbine blade of any preceding claim, wherein the inlet through-holes are configured to receive a coolant flow from a coolant flow supply.

25. The turbine blade of any preceding claim, wherein the outlet through-holes are configured to eject coolant to provide a film over an outer surface of the outer skin.

26. A gas turbine engine comprising the blade of any preceding claim.

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