EP1628076A1 - Cooling Channel, Combustor and Gas Turbine - Google Patents

Abstract

Cooling channel (11) comprises concave recesses arranged only outside of an edge zone on the hot gas wall (13). Preferred Features: The edge zone lies next to a side wall (21) having a transition section inclined to the hot gas wall. The transition section lies next to the edge zone of the hot gas wall. Concave recesses are arranged on a side wall, especially in the transition section.

Description

The invention relates to a cooling channel for guiding a cooling fluid. The invention also relates to a combustion chamber with such a cooling channel and a gas turbine with such a combustion chamber.

A combustion chamber is apparent from US 4,944,152 A1. The combustion chamber comprises a combustion chamber, which is surrounded by an annular space in which a cooling gas is guided. To avoid high temperature gradients strip-shaped paragraphs are provided in the annular cooling channel, which serve to equalize the cooling effect.

US Pat. No. 5,469,817 discloses a turbulator arrangement with the aid of which turbulences are generated in a cooling liquid in order to increase a heat transfer. In the configuration shown here, the turbulators are semicircular elevations. However, more common are elongated, rib-shaped turbulators, as used for example from US 5,426,943 for the turbulence generation in cooling air for cooling a gas turbine combustor. A particularly effective cooling method is the so-called impingement cooling, in which the cooling fluid flows from openings perpendicular to the surface to be cooled. With such an impingement cooling, however, a considerable pressure loss occurs. Such an impingement cooling is described, for example, in US Pat. No. 6,314,716 B1.

No. 6,134,877 describes for a gas turbine an impingement cooling combined with rib-shaped turbulators in the area of the gas turbine burners.

A recent concept for increasing heat transfer sees cooling by a cooling fluid on the cooling to be cooled Surface concave depressions, called dimples before. Such a concept for cooling a combustion chamber is described in US 6,098,397 A1. In such a dulled surface not only a very high heat transfer coefficient is achieved, but at the same time enables a comparatively low pressure loss. However, the solution described in US Pat. No. 6,098,397 A1 does not describe the cooling through a cooling channel with edge zones, since only one annular gap-shaped cooling channel is disclosed. When using a laterally limited cooling channel, there is a complication due to edge flow effects and associated difficult cooling of these edge zones. Even at high flow rates and high Reynolds numbers, the cooling of such a side wall area is very problematic.

The invention is therefore based on the object to provide a cooling channel with a side wall, which allows for a low pressure loss good cooling of the sidewall area. Another object of the invention is the disclosure of a particularly good coolable combustion chamber and a gas turbine with a well-cooled combustion chamber.

According to the invention, the object directed to a cooling channel is achieved by a cooling channel for guiding a cooling fluid along a flow direction, with a cooling channel height extending transversely to the flow direction, formed by side walls, and with a cooling channel width formed by a hot gas wall, the cooling channel width being greater than the cooling channel height, wherein an edge zone adjoining one of the side walls along the flow direction is formed on the hot gas wall with a peripheral zone width measured transversely to the flow direction, which edge zone width is at most one quarter of the cooling channel width and concave depressions are arranged only outside the edge zone on the hot gas wall.

The invention is based on the recognition that the concave depressions, which are also referred to as dimples as mentioned above, although allow a very good heat transfer coefficient and thus good cooling with low pressure loss, but insufficient by the generation of longitudinal vortices a sidewall region of a relative cool flat cooling channel. By now not being provided with Dimples the edge zone adjacent to such a side wall region of the hot gas wall to be cooled, a higher pressure loss, caused by the dimples, in the middle of the cooling channel compared to the edge zone is set. As a result, the cooling fluid is directed towards the side wall, i. In addition to the velocity component in the flow direction, a perpendicular velocity component directed at the side walls is achieved. This leads to improved cooling of just these margins.

In a preferred embodiment, the side walls on a relation to the hot gas wall inclined transition portion adjacent to the edge zone of the hot gas wall. Advantageously, the angle of inclination can be determined yes after constructive requirement and thermo-mechanical stress. The inclined transition section moreover achieves a further improved transport of the coolant in the direction of the side wall.

In this case, the transition section preferably has a rounding or bevel with a radius of curvature.

Preferably turbulators are arranged in the edge zone of the hot gas wall. Further improved cooling of the sidewall and rim is achieved by transverse vortices, in contrast to the longitudinal vortices created by the dimples. Such transverse vortices are generated by the specified turbulators. The combination of dimples in the central region of the cooling channel and preferably rib-shaped turbulators in the edge zone thus results in an optimized cooling both with regard to low pressure loss and with a view to good cooling of the edge zones and side walls.

Further preferably, turbulators are arranged on a side wall, in particular in the transition section of the side wall.

In a particularly preferred embodiment of the cooling channel, concave depressions are arranged on a side wall, in particular in the transition section of the side wall.

In one embodiment of the sidewall with a transition section as described above, concave depressions, e.g. spherical dimples, then preferably in the region of the transition section of a thermally lower loaded side wall. By contrast, a sidewall which is subjected to higher thermal loads preferably has web-shaped or knob-shaped turbulators with a high cooling effect in the transition section. These may be designed as chevron, i. have substantially V-shaped geometry with an as needed acute or obtuse opening angle. In this way, depending on the thermal load of the side wall locally well adapted cooling structure on the side wall can be flexibly realized, the turbulators in the form of longitudinal ribs, sockets, elevations (knobs) or chevrons (knobs) or, if necessary, may also include concave depressions and / or Combinations of all these a desired cooling effect causing flow elements.

Preferably, the edge zone width is about half as large to about one and a half times as large as the cooling channel height. With these size ratios of the edge zone width and the cooling channel height, the best compromise between pressure loss and edge zone cooling results.

Preferably, the turbulators are oriented on the hot gas wall to direct the cooling fluid toward the side wall. Preferably, the turbulators have a longitudinal extension and extend at an angle between 20 and 70 degrees, more preferably between 30 and 60 degrees measured perpendicular to the flow direction. In such an orientation results for the turbulators particularly good guidance of the cooling fluid in the direction of the side wall.

Preferably, turbulators are arranged on the side wall adjacent to the edge zone. These turbulators can be formed both rib-shaped and pedestal-shaped or in another geometry. This additional generation of turbulence on a side wall increases the heat transfer coefficient and thus leads to a further improved cooling of the side wall.

More preferably, the turbulators are arranged on the side wall measured from the edge zone to a height of at most 0.4, preferably 0.2 of the side wall height. Since the side wall extends transversely to the hot gas wall, the part of the side wall which is subjected to the highest thermal stress is that which borders on the hot gas wall. Therefore, only a part of the side wall needs to be intensified cooled by turbulators. In which only the indicated part of the side wall has turbulators, on the one hand the necessary cooling of the side wall, on the other hand a low pressure loss is made possible.

The object directed to a combustion chamber is achieved according to the invention by specifying a combustion chamber with a combustion chamber in which a hot gas can be generated and which has a cooling channel according to one of the embodiments described above. Accordingly, the object directed to a gas turbine is achieved by specifying a gas turbine with such a combustion chamber.

FIG 1

eine Gasturbine,

FIG 2 bis 4

einen Kühlkanal,

FIG 5 bis 8

Ausgestaltungen von Turbulatoren in einem Kühlkanal und

FIG 9

eine Gasturbinenschaufel.

The invention will be explained in more detail by way of example with reference to the drawing. They show, partly schematic and not to scale:

FIG. 1

a gas turbine,

FIGS. 2 to 4

a cooling channel,

FIGS. 5 to 8

Embodiments of turbulators in a cooling channel and

FIG. 9

a gas turbine blade.

1 shows a gas turbine 1. The gas turbine 1 has a compressor 3, a combustion chamber 5 and a turbine part 7. The combustion chamber 5 has a combustion chamber 6, which is bounded by lining elements, not shown, so-called liners. In these liners, each having a hot gas wall 13 toward the combustion chamber 6, a cooling channel 11 is formed. During operation of the gas turbine ambient air 9 is sucked into the compressor 3. The highly compressed air in the compressor 3 is passed as combustion air 9A in the combustion chamber 6 of the combustion chamber 5 and burned there with the addition of fuel to a hot gas 15. This hot gas 15 is passed through the turbine part 7 and thereby drives the gas turbine 1 at. A portion of the compressed air is passed as cooling fluid 9 B in the cooling channel 11. The proportion of the cooling air 9B must remain as low as possible in the gas turbine 1 in order to have as much combustion air 9A as possible for the actual combustion, in particular, for example, in an open cooling concept. This directly influences the efficiency and also the nitrogen oxide emission of the gas turbine 1. Frequently, therefore, cooling air 9B is also returned in a closed circuit and subsequently supplied to the combustion as combustion air 9A. The pressure built up in the compressor 3 stores potential energy, which in principle can also be used to drive the gas turbine 1. Pressure losses in the guide, in particular the cooling air 9B lead to a reduction of this potential energy and thus to a reduction of the efficiency.

A particularly low pressure loss guidance of the cooling fluid 9 B is therefore desirable. The cooling channel 11 has a flat cross-section. With closed cooling, it is flowed through by cooling air 9B at high speed. This leads to high Reynolds numbers of the flow and thus in particular to problems in the cooling of the side wall portions of the flat cooling channel 11. To improve the cooling of the side walls with simultaneous low pressure loss, therefore, the cooling channel 11 is carried out as described below.

FIG. 2 shows, in a cross section and a plan view, the configuration of a cooling channel 11 which is used in a lining element, a so-called liner 12, for lining the combustion chamber 5 of a gas turbine 1. The liner 12 has a rectangular cross-section and is hollow, wherein the cavity forms the cooling channel 11. The cooling channel 11 is thus formed of two side walls 21, a top wall 23 and a hot gas wall 13. The side walls 21 are inclined relative to the Heisgaswand 13, preferably as shown here by an inclination angle of about 90 °. The angle of inclination may also be less than 90 °. In this case, the side wall 21 may also have a rounded, chamfered or beveled transition section, which adjoins the hot gas wall 13. The side walls 21 form a cooling channel height H. The hot gas wall 13 forms a cooling channel width B. On the hot gas wall 13 is adjacent to a respective side wall 21, an edge zone 25 is formed, which has a edge zone width R, which is smaller than a quarter of the cooling channel width B. Between the edge zones 25, a central zone M is formed on the hot gas wall 13. The edge zone 25 of the hot gas wall 12 adjoins the side wall 21, which optionally has an inclined transition section - as already stated above. In the middle zone M, concave depressions, so-called dimples 27, are arranged. The edge zones 25, however, are free of such Dimples 27. The cooling channel 11 is now flowed through by the cooling air 9B. The dimples 27 thereby generate longitudinal swirls in the flow and thereby ensure a considerable amount improved heat transfer coefficient and thus for improved cooling. Compared with the use of turbulators 31, ie projections which generate turbulence in the flow of the cooling air 9B and thereby improve the heat transfer, the solution with dimples 27 has a significantly lower pressure loss. Nevertheless, the pressure loss in the central zone M is still greater than that of the uninfluenced flow in the edge zones 25. This means that a transverse flow component in the direction of the side walls 21 is set perpendicular to the flow direction of the cooling air 9B. This in turn means an increased cooling of the side walls 21 and the edge zones 25. Since, actually, increased cooling is achieved by the dimples 27, the omission of such dimples 27 initially seems paradoxical with a view to setting improved cooling. However, according to the invention, the dimples 27 generate a longitudinal swirling which does not lead to effective cooling in the region of the side walls 21 and edge zones R. By now with the omission of Dimples 27 in the edge zones 25, a flow component is generated in the direction of the side walls 21 so, as stated above, an increased cooling of the side areas.

FIG. 3 shows a cooling channel 11 corresponding to FIG. 2, but now turbulators 31 are arranged in the edge zones 25. In this configuration, the turbulators 31 are formed as longitudinal ribs, which are aligned parallel to each other and perpendicular to the flow direction, ie perpendicular to the side walls 21, at an angle α. This angle α is preferably between 30 and 70 degrees, wherein particularly particularly at 45 degrees a particularly good effect could be determined. The effect of these turbulators 31 is on the one hand that the heat transfer is improved by generating turbulence and on the other hand the cooling fluid 9B in addition to the effect of the pressure loss difference described in FIG. 2 is directed even more strongly to the side wall 21 and the edge zone 25. The turbulators 31 extend substantially over the entire edge zone width R, which, as well as in the free of turbulators 31 configuration of FIG 2, preferably about one to three times as large as the cooling channel height H.

In a further embodiment according to FIG 4, the turbulators 31 are pieced in their longitudinal direction, whereby a further improvement in the turbulence generation is achieved.

In the figures 5 to 8 additional turbulators 41 are arranged on the side wall 21, which can be formed both as longitudinal ribs, as shown in Figures 5 and 6, as well as in the form of sockets or projections according to Figures 7 and 8.

The side walls 21 are inclined relative to the Heisgaswand 13, preferably as shown here by an inclination angle of about 90 °. However, the angle of inclination may also be less than 90 °. In this case, the side wall 21 may also have a rounded, bevelled, or beveled transition section, which adjoins the hot gas wall 13. The hot gas wall 13 comprises - as shown in detail in Figure 2 in detail - a central zone M and an edge zone 25. Not shown in detail is the additional or alternative arrangement of concave depressions, eg Dimples 27, on a side wall 21, which is possible depending on the cooling requirement , Preferably, these are arranged in a transition section of the side wall 21, in particular beyond the dimple-free edge zone 25. Preferably, about 20% of the cooling channel height H is provided by the side wall 21 measured by the hot gas wall 13 with such turbulators 41. As a result, the thermally higher loaded part of the side wall 21 is effectively cooled. In this case, mutually opposite side walls 21 which delimit the cooling channel 11 may be configured with different turbulators 31 in shape and arrangement. For example, a possibly thermally higher loaded side wall 21 with web-shaped or knob-shaped turbulators 41 with high cooling effect and the other opposite side wall 21, the may be thermally lower loaded, with concave depressions in the side wall 21 - eg Dimples 27 - be designed with slightly lower cooling effect.

In an embodiment of the side wall 21 with a transition section (not shown in detail), dimples 27 are then preferably in the region of the transition section of a thermally lower loaded side wall 21. On the other hand, a thermally higher loaded side wall 21 preferably has web-shaped or knob-shaped turbulators 41 with high cooling effect in the transition section on.

In this way, a locally well adapted to the thermal load of the side wall 21 cooling structure on the side wall 21 can be realized flexibly, the turbulators 41 in the form of longitudinal ribs, sockets or projections (knobs) or - as not shown - include concave depressions (dimples) can and combinations of it.

9 shows a gas turbine blade 51. The gas turbine blade 51 has a blade leading edge 53 and a trailing edge 55, between which a pressure side 57 and a suction side 59 extend. The pressure side 57 and the suction side 59 enclose a cavity through which cooling air 9B is led along the blade axis. The cavity forms the cooling channel 11. Although this cooling channel 11 does not have a rectangular cross-section, it is nevertheless designed in the area of the blade leading edge 53 and the trailing edge 55 with edge zones corresponding to the previously described configurations. By now the cooling channel 11, as previously described, in the edge zones 25 without dimples 27, but with turbulators 31 and otherwise provided with dimples 27, a low-pressure-loss but effective cooling can be carried out especially the thermally stressed blade edges. In the gas turbine blade 51, the cavity may also be divided by longitudinal ribs, so that a plurality of cooling channels 11 is formed be through which the cooling air 9B passes, for example, meandering.

Claims (15)

Cooling channel (11) for guiding a cooling fluid (9B) along a flow direction, having a cooling channel height (H) formed by sidewalls (21) and a cooling channel width (B) formed by a hot gas wall (13), the cooling channel width (B) being formed B) is greater than the cooling channel height (H) and wherein an edge zone (25) adjoining one of the side walls (21) along the flow direction is formed with a rim zone width (R) measured transversely to the flow direction on the hot gas wall (13) extends up to a maximum of one quarter of the cooling channel width (B),
characterized in that only outside the edge zone (25) on the hot gas wall (11) concave depressions are arranged. Cooling channel (11) according to claim 1,
characterized in that the side wall (21) has a relation to the hot gas wall (13) inclined transition portion adjacent to the edge zone (25) of the hot gas wall (13). Cooling channel (11) according to claim 2,
characterized in that the transition section has a rounding or chamfer. Cooling channel (11) according to claim 1, 2 or 3, characterized in that in the edge zone (25) of the hot gas wall (13) turbulators (31) are arranged. Cooling passage (11) according to claim 2, 3 or 4,
characterized in that on a side wall (12), in particular in the transition section, turbulators (31) are arranged. Cooling passage (11) according to one of claims 2 to 5,
characterized in that on a side wall (12), in particular in the transition section, concave depressions are arranged. Cooling channel (11) according to one of the preceding claims,
characterized in that the edge zone width (B) is half as large to about twice as large as the cooling channel height. Cooling channel (11) according to one of the preceding claims,
characterized in that the edge zone width (B) is at least half as large, up to one and a half times as large as the cooling channel height (H). Cooling channel (11) according to one of claims 4 to 8,
characterized in that the turbulators (31) are oriented on the hot gas wall (13) so as to direct the cooling fluid (9B) toward the side wall (21). Cooling channel (11) according to one of the preceding claims,
characterized in that turbulators (41) are arranged on the side wall (21) adjoining the edge zone (25). Cooling passage (11) according to claim 10,
characterized in that the turbulators (41) on the side wall (21) measured from the edge zone (25) to a height of at most 0.4 times, preferably 0.2 times the side wall height are arranged. Cooling channel (11) according to one of the preceding claims,
characterized in that the turbulators (31, 41) have a longitudinal extent and extend at an angle between 20 and 70 degrees, preferably between 30 and 60 degrees, measured perpendicular to the flow direction. Combustion chamber (5) with a combustion chamber (6) in which a hot gas (15) can be generated and with a cooling channel (11) according to one of the preceding claims, wherein the hot gas wall (13) delimits the combustion chamber (6). Gas turbine blade (51) which is hollow, wherein the cavity forms a cooling channel (11) according to one of the preceding claims. Gas turbine (1) with a combustion chamber (5) according to claim 13.

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