A deswirler for cooling system and a cooling system of a turbomachine

The present invention relates to a cooling system of a turbomachine and more particularly to a deswirler for a cooling system of a turbomachine. In present day gas turbines, also referred to as a

turbomachine, cooling techniques and systems for cooling different internal parts, such as blades and vanes, of the turbomachine are of utmost importance. An efficient cooling of the internal parts of the turbomachine not only ensures higher operating temperatures, thereby increasing the output of the turbomachine, but also increases the operational life of the internal parts of the turbomachine by at least

partially protecting the structural integrity of the internal parts so cooled. An effective and prevalent way of cooling is achieved by using a part of air, as cooling air, from a main inlet or a main flow i.e. the air flow that feeds a

compressor section of the turbomachine. The cooling air is routed from the main flow of the turbomachine and directed to different internal parts, such as blades and vanes, of the turbomachine via a cooling channel. The cooling air is required to exit the cooling channel and into or onto the internal parts of the turbomachine in a defined direction of flow. Thus controlling or regulating the flow of cooling air into the cooling channel is important for efficient cooling of the internal parts of the turbomachine.

One way of directing the cooling air into the cooling channel is by use of a deswirler for example in some cases a

deswirler provides axial flow in the turbomachine. One or more of such deswirlers may be located at different parts of a cooling system in the turbomachine so as to ensure that the cooling air flows in a desired direction and with a desired swirl. In most cases the swirl of the cooling air is attempted to be reduced, also by using the deswirler, after directing the cooling air from the main flow of the

turbomachine and before introducing the cooling air into the cooling channels of the cooling system of the turbomachine.

The deswirler is usually formed in shape of a disk that rotates together along with a main shaft of the turbomachine. The disk of the deswirler comprises blades. The blades of the deswirler are present in between the disk surface and a shroud, which may usually be formed of a part of the

compressor disk. The region of the deswirler between the blades, and closed by the surface of the disk and the shroud, directs the cooling air into the cooling channels. However, the blades do not touch the shroud as the blades are rotating independent of the shroud and touching of the blade to the shroud will lead to catastrophic accidents when the

turbomachine is operated. Thus there exists a gap between tips of the blades of the deswirler and the shroud which leads into ⁽ bleeding' i.e. leakage from the desired directed flow of the cooling air and thereby the desired direction and deswirling effect of the deswirler is not achieved to

optimum.

Thus there is a need of a deswirler that reduces the amount of leakage of the cooling air in the deswirler i.e. while the cooling air is passing through the deswirler located in the cooling system of the turbomachine.

Thus the object of the present technique is to provide a deswirler and a cooling system in which the amount of leakage of the cooling air in the deswirler i.e. when the cooling air is being directed via the deswirler.

The above object is achieved by a deswirler according to claim 1 of the present technique, and a cooling system according to claim 11 of the present technique. Advantageous embodiments of the present technique are provided in

dependent claims. Features of claim 1 may be combined with features of dependent claims that depend on claim 1, and features of these dependent claims can be combined together. Similarly, features of claim 11 may be combined with features of dependent claims that depend on claim 11, and features of these dependent claims can be combined together.

According to an aspect of the present technique, a deswirler for a cooling system of a turbomachine is presented. The deswirler includes a hub, a disk extending annularly around the hub, and a plurality of deswirler blades. The disk includes a hub region surrounding the hub, a tip region at an outer edge of the disk, a first side of the disk and a second side of the disk. The first side of the disk and the second side of the disk are opposite faces of the disk. The

plurality of deswirler blades extend from the first side of the disk. Each deswirler blade includes a hub end, a tip end, at least two side walls, a root portion and a top surface. Each side wall extends between the hub end and the tip end. The root portion is in direct physical contact with the first side of the disk. The top surface is limited by the hub end, the tip end and the two side walls of the deswirler blade. At least one of the deswirler blades includes a three

dimensional groove located at the top surface of the

deswirler blade. As a result of the three dimensional groove, hereinafter the 3D groove or simply the groove, a

differential air pressure is created across the groove i.e. between a part of the groove adjoining one the two side walls of the deswirler blade and a part of the groove adjoining the other of the two side walls of the deswirler blade, when the deswirler blades, supported on the deswirler disk, are rotating together along with a main shaft of the

turbomachine. This difference in pressure acts as a barrier to the bleeding cooling air and thus at least partially reduced the bleed of the cooling air while the cooling air is passing through the deswirler.

In an embodiment of the deswirler, the three dimensional groove extends in a first direction along the top surface in between the hub end and the tip end, extends in a second direction along the top surface in between the two side walls, and extends in a third direction vertically with respect to the top surface in between the top surface and the root portion. This provides a precise location and extent of the groove .

In another embodiment of the deswirler, the three dimensional groove is enclosed within a body of the deswirler blade and open only at the top surface of the deswirler blade. Since the groove is enclosed within the body of the deswirler blade, formation of the groove is achieved easily during casting or machining of the deswirler blade without requiring any additional material to create a structure for

accommodating the groove.

In another embodiment of the deswirler, the three dimensional groove has an inlet at the tip end of the deswirler blade such that the three dimensional groove is in fluid

communication with an outside of the deswirler blade via the inlet of the three dimensional groove. Thus the bleeding of the cooling air is at least partially reduced starting at the entrance of the cooling air when the cooling air first comes into contact with the deswirler blade.

In another embodiment of the deswirler, the three dimensional groove has an outlet at the hub end of the deswirler blade such that the three dimensional groove is in fluid

communication with the outside of the deswirler blade via the outlet of the three dimensional groove. Thus the bleeding of the cooling air is at least partially reduced even at the exit of the cooling air from the deswirler.

In another embodiment of the deswirler, the three dimensional groove has a rectangular cross-section. This provides a simple form of the groove that can be easily integrated in the top surface of the deswirler blade. In another embodiment of the deswirler, the three dimensional groove has a semi circular cross-section. This provides another simple form of the groove that can be easily- integrated in the top surface of the deswirler blade.

In another embodiment of the deswirler, the three dimensional groove has a triangular cross-section. This provides another simple form of the groove that can be easily integrated in the top surface of the deswirler blade.

In another embodiment of the deswirler, the deswirler further includes a shroud positioned along the top surfaces of the deswirler blades . Thus the need of an external surface to cover the region between the fist side of the disk and the deswirler blades is obviated. In the present technique by having the groove on the deswirler blades, tip leakages between deswirler blade and shroud are at least partially reduced. In another embodiment of the deswirler, the shroud is a part of a compressor disk in the turbomachine . Thus the shroud is realized by the compressor disk thereby obviating the need of an additional structure to serve only as shroud. According to another aspect of the present technique, a cooling system of a turbomachine is presented. The cooling system includes a cooling air inlet path, a cooling channel and a deswirler. The cooling air inlet path is configured to draw a cooling air from a main air flow of the turbomachine. The cooling channel runs along at least a part of a main shaft of the turbomachine. The deswirler fluidly connects the cooling air inlet path and the cooling channel. The deswirler includes a hub, a disk, and a plurality of deswirler blades. The hub is adapted to engage with the main shaft of the turbomachine. The disk extends annularly around the hub. The disk includes a hub region surrounding the hub, a tip region at an outer edge of the disk, a first side of the disk and a second side of the disk. The first side of the disk and the second side of the disk are opposite faces of the disk. The plurality of deswirler blades extend out of the first side of the disk. A flow channel is formed between two adjacent deswirler blades and the first side of the disk. The flow channel forms a flow path for the cooling air. The flow channel includes a flow channel inlet configured to receive the cooling air from an outside of the deswirler and a flow channel outlet configured to release the cooling air into the cooling channel.

Each deswirler blade includes a hub end, a tip end, at least two side walls, a root portion and a top surface. Each side wall extends between the hub end and the tip end. The root portion is in direct physical contact with the first side of the disk. The top surface is limited by the hub end, the tip end and the two side walls of the deswirler blade. At least one of the deswirler blades includes a three dimensional groove located at the top surface of the deswirler blade. As a result of the three dimensional groove, hereinafter the 3D groove or simply the groove, a differential air pressure is created across the groove i.e. between a part of the groove adjoining one the two side walls of the deswirler blade and a part of the groove adjoining the other of the two side walls of the deswirler blade, when the deswirler blades are

rotating around a main shaft of the turbomachine . This difference in pressure acts as a barrier to the bleeding cooling air and thus at least partially reduced the bleed of the cooling air while the cooling air is passing through the deswirler .

In an embodiment of the cooling system, the three dimensional groove of the deswirler blade extends in a first direction along the top surface of the deswirler blade in between the hub end and the tip end, extends in a second direction along the top surface of the deswirler blade in between the two side walls, and extends in a third direction vertically with respect to the top surface of the deswirler blade in between 15 000511

7 the top surface and the root portion of the deswirler blade. This provides a precise location and extent of the groove.

In another embodiment of the cooling system, the three dimensional groove of the deswirler blade is enclosed within a body of the deswirler blade and open only at the top surface of the deswirler blade. Since the groove is enclosed within the body of the deswirler blade, formation of the groove is achieved easily during casting or machining of the deswirler blade without requiring any additional material to create a structure for accommodating the groove.

In another embodiment of the cooling system, the three dimensional groove of the deswirler blade has an inlet at the tip end of the deswirler blade such that the three

dimensional groove is in fluid communication with an outside of the deswirler blade via the inlet of the three dimensional groove. Thus the bleeding of the cooling air is at least partially reduced starting at the entrance of the cooling air when the cooling air first comes into contact with the deswirler blade.

In another embodiment of the cooling system, the three dimensional groove of the deswirler blade has an outlet at the hub end of the deswirler blade such that the three dimensional groove is in fluid communication with the outside of the deswirler blade via the outlet of the three

dimensional groove. Thus the bleeding of the cooling air is at least partially reduced even at the exit of the cooling air from the deswirler.

In another embodiment of the cooling system, the three dimensional groove has a rectangular cross-section. This provides a simple form of the groove that can be easily integrated in the top surface of the deswirler blade.

In another embodiment of the cooling system, the three dimensional groove has a semi circular cross-section. This provides another simple form of the groove that can be easily integrated in the top surface of the deswirler blade.

In another embodiment of the cooling system, the three dimensional groove has a triangular cross-section. This provides another simple form of the groove that can be easily integrated in the top surface of the deswirler blade.

In another embodiment of the cooling system, the deswirler further comprises a shroud positioned along the top surfaces of the deswirler blades. The flow channel is formed by the two adjacent deswirler blades, the first side of the disk and an inner wall of the shroud. Thus the need of an external surface to cover the region between the fist side of the disk and the deswirler blades top form the flow channel is obviated.

In another embodiment of the cooling system, the shroud is a part of a compressor disk in the turbomachine . Thus the shroud is realized by the compressor disk thereby obviating the need of an additional structure to serve only as shroud.

The present technique is further described hereinafter with reference to illustrated embodiments shown in the

accompanying drawing, in which: schematically illustrates a turbomachine with a cooling system including a deswirler, in accordance with aspects of the present technique; schematically illustrates a disk of the deswirler;

FIG 3 schematically illustrates a top view of the disk of the deswirler including a plurality of deswirler blades ; 15 000511

schematically illustrates a cross-sectional view of the disk of the deswirler showing one deswirler blade; schematically illustrates a top view of the disk of the deswirler showing the plurality of deswirler blades in simplified representation; schematically illustrates a top view of the disk of the deswirler showing a shroud; schematically illustrates a perspective view of a part of the disk of the deswirler showing one deswirler blade; schematically illustrates a perspective view of the part of the disk of the deswirler of FIG 7 showing the deswirler blade with a three dimensional groove ; schematically illustrates a cross-sectional view of the part of the disk of the deswirler showing the deswirler blade with the three dimensional groove Of FIG 8; schematically illustrates a perspective view of another embodiment of the part of the disk of the deswirler showing the deswirler blade with the three dimensional groove having a rectangular cross-section; schematically illustrates a perspective view of another embodiment of the part of the disk of the deswirler showing the deswirler blade with the three dimensional groove having a semi-circular cross-section; 15000511

10 schematically illustrates a perspective view of another embodiment of the part of the disk of the deswirler showing the deswirler blade with the three dimensional groove having a triangular cross- section; schematically illustrates a perspective view of another embodiment of a part of the disk of the deswirler showing adjacent deswirler blades with the three dimensional grooves; and schematically illustrates a cross-sectional view of the embodiment of FIG 13 depicting the part of the disk of the deswirler showing adjacent deswirler blades with the three dimensional grooves, in accordance with aspects of the present technique.

Hereinafter, above-mentioned and other features of the present technique are described in details. Various

embodiments are described with reference to the drawing, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purpose of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more embodiments. It may be noted that the illustrated embodiments are intended to explain, and not to limit the invention. It may be evident that such embodiments may be practiced without these specific details. Referring to FIG 1, a turbomachine 5 with a cooling system

100 including a deswirler 1, in accordance with aspects of the present technique, is schematically illustrated. The turbomachine 5 may be a gas turbine or a gas turbogenerator. The turbomachine 5 includes a main air flow 6 directed towards compressor blades 8. The turbomachine 5 also includes compressor disks 7 and a main shaft 9 on which the compressor disks 7 are mounted. The turbomachine 5 includes a cooling system 100. The cooling system 100 has a cooling air inlet path 110 via which a part of the main air flow 8 is directed into the cooling system 100. The part of the main air flow 8 directed into the cooling system 100 is represented by arrows marked with reference numeral 4. The cooling air 4 after being directed from the main air flow 8 via the cooling air inlet path 110 is directed into a cooling channel 120 via the deswirler 1. The cooling channel 120 runs along at least a part of the main shaft 9 of the turbomachine 5. The cooling channel 120 may then direct the cooling air flow 4 to other parts of the turbomachine 5 for example into rotor blades

(not shown) in order to cool the other parts for example by film cooling.

In the cooling system 100, the deswirler 1 fluidly connects the cooling air inlet path 110 and the cooling channel 120.

Thus path of the cooling air flow 4 is from the main air flow 8 through the cooling air inlet path 110 to an outside 99 of the deswirler 1, then into the deswirler 1 and subsequently into the cooling channel 120. The cooling air flow 4 may exit the deswirler 1 into the outside 99 of the deswirler 1 and then enter into the cooling channel 120 or may exit the deswirler 1 directly into the cooling channel 120 i.e. the cooling channel 120 forms the outside 99 of the deswirler 1. As shown in FIG 2, the deswirler 1 includes a hub 10 and a disk 20. The hub 10 is the part of the deswirler 1 that engages with the main shaft 9, for example the hub 10 may be a hole through which the main shaft 9 passes thereby

stabilizing the deswirler 1 around the main shaft 9 and enabling the disk 20 of the deswirler 1 to rotate along with the main shaft 9. The disk 20 extends annularly around the hub 10. The disk 20 comprises a hub region 22 i.e. a portion of the disk 20 surrounding the hub 10. The disk 20 also comprises a tip region 24 i.e. another portion of the disk 20 adjoining an outer edge 21 of the disk 20, as depicted in FIG 2. The disk 20 is basically a circular disk with two sides - a first side 26 and a second side 28. The first side 26 and the second side 28 are opposite faces of the disk 20. 2015/000511

12

As shown in FIG 3, the deswirler 1 includes a plurality of deswirler blades 30 which were not shown in FIG 2. The plurality of deswirler blades 30 has been represented in a simplified form in FIG 5. The deswirler blades 30 are on the first side 26 of the disk 20. The deswirler blades 30 extend out of the first side 26 of the disk 20 which is better understood by FIG 4. As depicted in FIG 5 in combination with FIGs 3 and 4, each deswirler blade 30 includes a hub end 32 i.e. end or side of the deswirler blade 30 towards the hub 10 and along the hub region 22 of the disk 20, and a tip end 34 i.e. end or side of the deswirler blade 30 towards the edge 21 of the disk 20 and along the tip region 24 of the disk 20. The deswirler blade 30 also includes at least a first side wall 36 and a second side wall 37. Each side wall 36,37 extends between the hub end 32 and the tip end 34. As shown in FIG 4 and FIG 7, each deswirler blade 30 has a root portion 38 and a top surface 40. The root portion 38 is in direct physical contact with the first side 26 of the disk 20. The top surface 40 is limited by the hub end 32, the tip end 34 and the two side walls 36,37 of the deswirler blade 30.

As shown in FIG 8, in accordance with aspects of the present technique, at least one of the deswirler blades 30 includes a three dimensional groove 50, hereinafter referred to as the groove 50 or the 3D groove 50, located at the top surface 40. The location of the groove 50 at the top surface 40 in FIG 8 may be understood by comparison of FIG 8 with FIG 7, wherein FIG 8 depicts the groove 50 whereas FIG 7 does not depict the groove 50. The groove 50 may be understood as a cut or canal or furrow or channel along the top surface 40. As depicted in FIG 8, the groove 50 extends in a first direction 55 along the top surface 40 in between the hub end 32 and the tip end 34, extends in a second direction 56 along the top surface 40 in between the two side walls 36,37, and extends in a third direction 57 vertically with respect to the top surface 40 in between the top surface 40 and the root portion 38 of the 00511

deswirler blade 30. The groove 50 in the first direction 55 may extend up to a length equal to a distance between the hub end 32 and the tip end 34 of the deswirler blade 30 along the top surface 40. The groove 50 in the second direction 56 may extend up to a width equal to a distance between the two walls 36,37 of the deswirler blade 30 along the top surface 40. The groove 50 in the third direction 57 may extend up to a depth equal to half of a distance between the top surface 40 and the first surface 26 of the disk.

The groove 50 may have variety of forms. For example, as shown in FIG 8, in an embodiment, the groove 50 is enclosed within a body 2 of the deswirler blade 30 and open only at the top surface 40 of the deswirler blade 30. This means that only a surface of the groove 50 that is in a plane formed by directions 55 and 56 is open while other surfaces formed for example surfaces formed by directions 56 and 57 and by directions 55 and 57 are within the body 2 of the deswirler blade 30 and thus not open.

In another embodiment of the deswirler 1, as shown in FIG 10, the groove 50 has an inlet 54 at the tip end 34 of the deswirler blade 30 such that the three dimensional groove 50 is in fluid communication with the outside 99 (as shown in FIG 1) of the deswirler blade 30 via the inlet 54 of the three dimensional groove 50. Furthermore, as also shown in FIG 10, the groove 50, in another embodiment, has an outlet 52 at the hub end 32 of the deswirler blade 30 such that the three dimensional groove 50 is in fluid communication with the outside 99 (as shown in FIG 1) of the deswirler blade 30 via the outlet 52 of the three dimensional groove 50. The outside 99 communicating with the outlet 52 may be the cooling channel 120 as depicted in FIG 1. Furthermore, the groove 50 may have different cross-sectional shapes. In one embodiment as shown in FIGs 8 and 9, the groove 50 has a rectangular cross-section. In another

embodiment as shown in FIG 11, the groove 50 has a semi 15 000511

14 circular cross-section. In yet another embodiment as shown in FIG 12, the groove 50 has a triangular cross-section.

It may be noted that in one embodiment of the deswirler 1, the deswirler does not have a dedicated shroud, however in an alternate embodiment, as depicted in FIG 6, the deswirler 1 further includes a shroud 60 positioned along the top

surfaces 40 of the deswirler blades 30. The shroud 60 is a cover or envelope over the top surface 40 of the plurality of deswirler blades 30. The presence of the shroud 60 at the top surfaces 40 of the deswirler 1 may be understood more clearly by comparison of FIG 6 with FIG 5, wherein FIG 6 depicts the shroud 60 whereas FIG 5 does not depict the shroud 60. It may be noted that, as depicted in FIG 9, the top surface 40 of the deswirler blade 30 does not come in direct physical contact with the shroud 60. As shown in FIG 9, an inner wall 62 of the shroud 60 is towards the top surface 40 but not in direct contact with the top surface 40. The shroud 60 may be a separate unit as shown in FIG 6 or may be a part of a compressor disk 7 in the turbomachine 5 as depicted in FIG 1.

Now referring to FIGs 13 and 14, in combination of FIG 1, a perspective view of another embodiment of a part of the disk 20 of the deswirler 1 showing adjacent deswirler blades 30 with the three dimensional grooves 50 are schematically depicted in FIG 13, whereas in FIG 14 a cross-sectional view of the embodiment of FIG 13 depicting the part of the disk 20 of the deswirler 1 showing adjacent deswirler blades 30 with the three dimensional grooves 50 on each of the deswirler blades 30 is schematically depicted.

As shown in FIG 1, in combination with FIGs 13 and 14, the cooling system 100 that includes the cooling air inlet path 110, the cooling channel 120 has the deswirler 1 positioned between the cooling air inlet path 110 and the cooling channel 120 along the cooling air flow 4. A flow channel 70 as depicted in FIG 13 is formed between two adjacent

deswirler blades 30 and the first side 26 of the disk 20. The RU2015/000511

flow channel 70 forms a flow path 72 for the cooling air. The flow channel 70 includes a flow channel inlet 74 configured to receive the cooling air from the outside 99 of the

deswirler 1. The flow channel 70 also includes a flow channel outlet 76 configured to release the cooling air into the cooling channel 120. In presence of the shroud 60, formed by the compressor disk 7 or formed of another unit (not shown) independent of the compressor disk 7, the flow channel 70 is formed by the first side 26 of the disk 20, the two adjacent deswirler blades 30 and the inner wall 62 of the shroud 60. The cooling air flow 4 flows through the flow channel 70 inside the deswirler 1, and the bleeding of the cooling air flow is reduced by the grooves 50 on the two adjacent

deswirler blades 30.

While the present technique has been described in detail with reference to certain embodiments, it should be appreciated that the present technique is not limited to those precise embodiments. Rather, in view of the present disclosure which describes exemplary modes for practicing the invention, many modifications and variations would present themselves, to those skilled in the art without departing from the scope and spirit of this invention. The scope of the invention is, therefore, indicated by the following claims rather than by the foregoing description. All changes, modifications, and variations coming within the meaning and range of equivalency of the claims are to be considered within their scope.