EP2846000B1 - Vane ring of a gas turbine - Google Patents

Description

The invention relates to a turbine stator, in particular a high-pressure turbine stator of a gas turbine, in particular for use in a gas turbine engine.

It is known from the prior art that the guide vanes of a turbine guide wheel must be designed in particular according to aerodynamic requirements. On the one hand, the contouring of the blade cross-section on the suction side and on the pressure side plays a major role. The design of the blade passage between adjacent guide blades is also important here, since the flow cross section available through the passage also determines the efficiency of the guide wheel.

In the aerodynamic design, however, particular attention must be paid to ensuring that the guide vanes of the guide wheel burn back. In this context, burn-back capability of the stator is to be understood to mean that during operation of the gas turbine, in particular the rear edge of the first stator of the high-pressure turbine can burn off under the extreme thermal loads that occur. This means that the guide blade, starting from the rear edge of the blade, is shortened by the burn-back. Since the first stator of a high-pressure turbine largely determines the flow through the entire turbomachine, it is crucial to maintain the flow (capacity) of the first stator so that the entire turbomachine and all individual components can continue to work at a nominal mass flow at the design point. It is therefore necessary that the flow (capacity) of the turbine does not change significantly as a result of the burn-back.

In order to ensure the backburning criterion of a turbine stator, the passage cross section within the stator upstream of the narrow cross section (i.e. in the direction of the progressive backburn of the trailing edge of the blade) must remain approximately constant, so that the then effective narrow passage cross section also remains approximately constant even when the thermally highly stressed trailing edge burns back. This ensures that the flow rate remains the same even in the event of a backburn. Such an embodiment is for example from the Figure 4 of the DE 10 2005 025 213 A1 known.

Further examples of turbine idlers, in which the guide vanes have a convex pressure side contour on the pressure side, show the DE 10 2004 009 696 B3 and the DE 100 54 244 A1 .

The disadvantage of the stator wheel designs known from the prior art is that the aerodynamic design cannot be designed to be loss-optimized, since the generally advantageous design with strong aerodynamic loads in the rear suction side area (“rear-loaded design”) sustainably violates the burn-back criterion. A compromise must therefore always be made in the aerodynamic design so that the burn-back capability is ensured. This in turn reduces turbine efficiency and increases the specific fuel consumption (SFC) of the turbomachine.

The invention has for its object to provide a turbine stator of the type mentioned, which has a high efficiency with a simple structure and simple design, while at the same time the mentioned burn-back criterion is met. Especially in the event of a backfire, the turbine capacity should remain largely unchanged so that the entire engine with its individual components can continue to be operated at the design point.

According to the invention the object is achieved by the combination of features of claim 1. The subclaims show advantageous embodiments of the invention.

The solution according to the invention then considers a turbine stator, in which two adjacent guide blades each form a passage which comprises a constant passage section. The constant passage section is characterized in that it has an essentially constant passage cross section. The constant passage section has an entry area into the constant passage section and an exit area. The exit area is located at the rear edge of the blade and is identical to the narrowest cross section (narrow cross section) of the passage. On the pressure side, each guide vane forms a rear area which, starting from the rear edge of the blade, extends adjacent to the constant passage section to the entry area of the passage section, and a front area which extends upstream of the rear area. The rear area is therefore the area of the pressure side of the guide vane that delimits the constant passage section.

It is provided according to the invention that the guide vanes have a convex pressure side contour on the pressure side, which produces a transition from the rear area of the guide blade to the front area of the guide blade.

The solution according to the invention provides a convex pressure side contour on the pressure side of the guide vane, in such a way that the convex pressure side contour creates a transition from a rear area of the guide vane, in which there is a constant passage section, to a front area of the guide vane. The rear area of the guide vane is thus connected to the front area of the guide vane via the convex pressure side contour.

The convex pressure side contour or the convex curvature of the pressure side provided by this enables the passage between two guide blades to be made constant over a certain length, even if the adjacent guide blade is provided with a considerable convex curvature on the suction side in order to implement a loss-optimized turbine stator which without compensation by the convex pressure side contour - would lead to a considerable widening of the passage. The invention thus ensures burn-back capability even in the event that a loss-optimized turbine stator with guide vanes with considerable convex curvature on the suction side is provided in the region of the narrow cross section.

While in the case of constructions known in the prior art, the walls of the suction side and of the pressure side adjacent to the trailing edge of the blade are essentially rectilinear or have a uniform curvature and thus form a wedge-shaped cross-sectional area of the guide vane, the solution according to the invention thus provides that the wall of the pressure side of the Guide vane forms a convex pressure side contour, that is to say a convex curvature, which forms the transition between the rear region of the guide vane, which adjoins the constant passage section, and the front region, which extends upstream thereof.

The invention produces the burn-back capability by convex contouring of the pressure side of the guide vane of the guide wheel, without the aerodynamic design of the suction side of the guide vane being influenced. According to the invention, it is therefore possible to freely define the suction side of the guide vane of the guide wheel and to make it optimal in terms of loss technology, and to implement guide vanes with a considerable convex curvature of the suction side in the region of the narrow cross section or adjacent to the narrow cross section. The configuration according to the invention of the pressure-side contour of the guide vane ensures that the cross-section of the passage between adjacent guide vanes remains essentially constant in the event of a burn-back, so that the flow (capacity) of the turbine and thus the efficiency of the overall engine due to a burn-back do not or only insignificantly to be influenced.

According to one embodiment of the invention, it is provided that the profile thickness of the guide blades increases or is constant in the direction of the blade rear edge in front of the rear region of the guide blades or decreases to a lesser extent than in the rear region of the guide blade. In other words, this embodiment provides that the profile thickness increases or is constant in the direction of the blade trailing edge in front of the entry region into the passage or decreases to a lesser extent than in the region of the constant passage section. This corresponds to the training of the convex pressure side contour on the pressure side of the guide vane, which just ensures that the profile thickness of the guide vanes increases in front of the constant passage section, is essentially constant or only slightly decreases, compared with a greater decrease in the profile thickness in the rear area of the guide vane up to the rear edge of the vane .

According to a further embodiment of the invention, it is provided that the convex pressure side contour forms a maximum in the constant passage cross section at or upstream of the entry region. It can further be provided that the convex pressure side contour forms a maximum of the curvature at or upstream of the entry area in the constant passage cross section. The maximum of the curvature is close to the point furthest locally from the printing side or close to the line furthest from the printing side. The maximum and / or the maximum of the curvature are therefore not in the rear area of the guide vane, but in the front area of the guide vane, but preferably at a short distance from the rear area (for example at a distance that corresponds to a maximum of 10% of the length of the skeleton line ) or directly at the transition between the two areas.

A further embodiment of the invention provides that the convex pressure side contour on the pressure side of the guide blades is predominantly or completely formed in the front area of the guide blade. It can be provided that part of the convex pressure side contour is additionally formed in the rear area of the guide vane. In principle, however, a rectilinear or even concave curvature can be provided in the rear area of the guide vane, which delimits the constant passage section, which merges into the convex pressure side contour.

In the sense of the present invention, there is an essentially constant passage cross-section if the passage cross-section does not deviate by more than 5% from the narrow cross-section in the region of the blade rear edge. This deviation from the narrow cross section is preferably less and is less than 2% of the narrow cross section. Ideally, the passage cross section is exactly constant in the constant passage section. It can further be provided that the constant passage section extends over a chord length, for example in the area is between 5% and 40% of the total tendon length and is, for example, about 5%, 10%, 15%, 20%, 25%, 30%, 35% or 40% of the total tendon length.

Basically, it can be provided that the convex pressure side contour extends over the entire height of the guide vane. Furthermore, it can be provided that the pressure side contour extends at least over a partial area of the blade height (for example over at least 50% or at least 70% of the blade height). It is also possible for the configuration of the curvature to vary over the blade height.

It is particularly expedient if the guide blade, starting from the rear edge of the blade, is provided with a concave area after the convex area. This configuration leads in particular to an optimal surface pressure distribution on the blade surface.

The following advantages result according to the invention:

According to the invention, there is an increase in aerodynamic efficiency since, compared to a configuration of the guide vanes according to the prior art, there is an increase in the step efficiency.

Another advantage is the mechanical stability. The convex pressure side contour of the guide vane results in a significantly higher wedge angle, adjacent to the trailing edge of the vane, compared to the prior art. The profile is therefore thicker in the rear edge area. This in turn leads to increased mechanical stability, which results in a far less deformation of the rear edge under thermal stress during operation.

The turbine stator according to the invention also has considerable advantages with regard to cooling air consumption. Since the blade contour has a greater thickness in the trailing edge area, it is possible to expand the internal cooling geometry further in the direction of the trailing edge of the blade. This can be done, for example, by so-called pedestal banks located further back. This gives the opportunity Saving cooling air, since the length of the rear edge overhang, which is difficult to cool and has the greatest thermal load, can be reduced.

Due to the mechanically more stable and better cooling rear edge area, the inventive configuration of the cross section of the guide vanes results in a longer service life.

Another advantage is the stability of the engine properties and the turbine efficiency in long-term operation. The engine flow changes less in long-term operation due to the more stable and easier-to-cool blade trailing edge. The decrease in high pressure turbine efficiency due to the increase in trailing edge losses due to burn back is reduced.

Another significant advantage is the cost savings from longer life and reduced engine development costs. Engine development costs can be reduced because of the reliable capacity prediction, since the need for the subsequent capacity change is reduced. Engine development time can also be reduced.

Fig. 1

eine schematische Darstellung eines Gasturbinentriebwerks gemäß der vorliegenden Erfindung,

Fig. 2

eine Teilansicht eines Turbinenleitrads gemäß dem Stand der Technik,

Fig. 3

eine Ansicht eines ersten erfindungsgemäßen Ausführungsbeispiels,

Fig. 4

eine Ansicht eines zweiten erfindungsgemäßen Ausführungsbeispiels,

Fig. 5

eine Vergleichsansicht der Ausgestaltung gemäß dem Stand der Technik (linke Bildhälfte) und der erfindungsgemäßen Ausführungsbeispiels der Fig. 4 (rechte Bildhälfte), und

Fig. 6

in der oberen Bildhälfte die statischen Oberflächendrücke der Ausgestaltung gemäß dem Stand der Technik (entsprechend Fig. 5 links) sowie in der unteren Bildhälfte die statischen Oberflächendrücke der Ausgestaltung gemäß einem erfindungsgemäßen Ausführungsbeispiel (entsprechend Fig. 5 rechts).

The invention is described below on the basis of exemplary embodiments in conjunction with the drawing. It shows:

Fig. 1

1 shows a schematic illustration of a gas turbine engine according to the present invention,

Fig. 2

2 shows a partial view of a turbine stator according to the prior art,

Fig. 3

2 shows a view of a first exemplary embodiment according to the invention,

Fig. 4

2 shows a view of a second exemplary embodiment according to the invention,

Fig. 5

a comparative view of the configuration according to the prior art (left half of the image) and the embodiment of the invention Fig. 4 (right half of the picture), and

Fig. 6

in the upper half of the picture, the static surface pressures of the design according to the prior art (corresponding Fig. 5 left) and in the lower half of the picture the static surface pressures of the embodiment according to an embodiment of the invention (accordingly Fig. 5 right).

The gas turbine engine 10 according to Fig. 1 Fig. 4 is a generally illustrated example of a turbomachine to which the invention can be applied. The engine 10 is constructed in a conventional manner and comprises an air inlet 11, a fan 12 rotating in a housing, a medium-pressure compressor 13, a high-pressure compressor 14, a combustion chamber 15, a high-pressure turbine 16, a medium-pressure turbine 17 and a low-pressure turbine 18 and one in the flow direction Exhaust nozzle 19, which are all arranged around a central engine axis 1.

The medium pressure compressor 13 and the high pressure compressor 14 each comprise a plurality of stages, each of which has a circumferential arrangement of fixed stationary guide vanes 20, which are generally referred to as stator blades, and which extend radially inward from the core engine housing 21 in an annular flow channel through the compressors 13, 14 protrude. The compressors also have an arrangement of compressor blades 22 which project radially outward from a rotatable drum or disk 26 which is coupled to hubs 27 of the high-pressure turbine 16 and the medium-pressure turbine 17.

Turbine sections 16, 17, 18 have similar stages, including an array of fixed vanes 23 projecting radially inward from housing 21 into the annular flow channel through turbines 16, 17, 18 and a subsequent array of turbine blades 24 which protrude outward from a rotatable hub 27. The compressor drum or compressor disk 26 and the blades 22 arranged thereon as well as the turbine rotor hub 27 and the Turbine rotor blades 24 arranged thereon rotate during operation about the engine axis 1.

The Fig. 2 shows a view of a turbine stator known from the prior art with an end view of adjacent guide vanes 23. These each have a pressure side 30 and a suction side 31 and form a passage 29 through which the hot gases emerging from the combustion chamber flow. From the representation of the Fig. 2 it follows that the passage 29 has a narrowest cross-section (narrow cross-section 36) in the region of a blade rear edge 32. This is designed with regard to the target profile shape of the guide vanes 23. The thermal load during operation causes the area of the blade trailing edge 32 to burn off, so that a burn-back 35 results. This means that the hatched area of the blade profile burns off. This results in an effective passage cross section 37, which is considerably widened compared to the narrow cross section 36 and consequently leads to a significant reduction in efficiency. The flow and the capacity change with the widening of the passage cross-section.

The problem described is all the greater, the more the tubular stator is designed as a loss-optimized turbine stator and for this purpose has guide vanes 23 which are provided with a considerable convex curvature on the suction side 31 in the region of the narrow cross-section 36 or adjacent to the narrow cross-section 36, which in the case of a Burnback leads to a considerable widening of passages.

The Figure 3 shows a view of an embodiment of the invention. The guide vanes 23 in turn have a pressure side 30 and a suction side 31, two adjacent guide vanes 23 forming a passage 29 between the suction side 31 of one guide vane and the pressure side 30 of the other guide vane, starting from the trailing edge 32 of the blade, through which hot gases emerging from the combustion chamber stream. It is provided that the passage 29 comprises a constant passage section 29a, in which the passage 29 has an essentially constant passage cross section 37.

The constant passage section 29a has an entry area 38 and an exit area 36, which essentially have the same passage cross section.

The exit area 36 is delimited by the blade rear edge 32, so that the exit area 36 corresponds to the narrow cross section of the passage 29.

The statement that the passage cross-section 37 in the constant passage section 29a is essentially constant means that the deviation of the passage cross-section 37 from the narrow cross-section in this constant passage section 29a is below a defined value which is defined as 5% of the narrow cross-section.

The guide vane 23 also forms a rear region 320 on the pressure side, which extends from the trailing edge 32 of the blade adjacent to the constant passage section 29a to the entry region 38 of the constant passage section 29a. The pressure-side rear region 320 of the guide vane is therefore the region that delimits the constant passage section 29a on the pressure side. A front area 310 extends upstream of the rear area 320, which basically extends to the front edge of the blade, but only the area adjacent to the rear area 320 is considered in detail for the purposes of the present invention.

The guide vane 23 also has a convex pressure side contour 33 on the pressure side 30, which creates a transition from the rear region 320 to the front region 310. This means that the convex pressure side contour 33 is formed in the transition area between the two areas 310 and 320, it being able to extend exclusively in the front area 310 or alternatively over both areas 310, 320. The convex pressure side contour 33 has a maximum M, which in the cross-sectional view of FIG Figure 3 indicates the point at which the curvature provided by the convex pressure side contour 33 locally protrudes the most from the pressure side 30.

Associated with the convex pressure side contour 33 is a certain profile of the profile thickness d of the guide vane 23. If one considers the profile profile d in the direction of the blade trailing edge 32, it is the case that the profile thickness d is in front the rear area 320 (or in front of the entry area 38) increases or is constant, as is the case with the profile thicknesses d1 and d2 Figure 3 is illustrated. In contrast, in the rear region 320 of the guide vane, the profile thickness d decreases relatively strongly, as is shown by way of example using the profile thickness d3. Alternatively, it can also be provided that the profile thickness in front of the rear region 320 does not increase or is constant, but decreases to a smaller extent (ie by a smaller value per unit length) than in the rear region 320. This profile profile d corresponds with the realization of a maximum M of the curvature provided by the convex pressure side contour 33 in front of or at the entry area into the constant passage section 29a.

The provision of a convex pressure side contour 33 leads, on the one hand, to an increase in the wedge angle between the surfaces of the pressure side 30 and the suction side 31 in the region adjacent to the trailing edge 32 of the blade and, in particular, to avoid widening of the passage cross section in the event of a backburn. Such widening is avoided precisely by the fact that a constant passage section 29a is provided by the solution according to the invention, so that the narrow cross-section does not change in the region of this constant passage section 29a in the event of a backburn 35. A burn back 35 is in the Figure 3 marked very exaggerated to better explain the effectiveness of the invention. It follows that the passage cross section 37 in the constant passage cross section 29a remains essentially the same in the event of a backburn, since the narrow cross section 36 in this section is essentially the same as the passage cross section 37.

The Figure 4 shows a further embodiment of two guide vanes 23 of a turbine stator according to the invention. Basically, the embodiment corresponds to the embodiment of FIG Figure 3 to which reference is made with regard to the reference symbols used. In turn, it is provided that by providing a convex pressure side contour 33 on the pressure side 30 of the guide vane 23, the rear area 320 of the guide vane 23 is given a shape which allows a constant passage section 29a with an essentially constant passage cross section 29a to be provided between an entry area 38 and to provide an exit area 36 of this constant passage section 29a.

The corresponding curvature of the convex pressure side contour 33 means that the profile thickness d of the guide vane 23 in front of the rear area 320 increases or remains essentially constant and only decreases sharply in the rear area 320 of the guide vane (cf. profile thicknesses d1, d2 and d3) Figure 4 ).

A difference in the design of the Figure 4 compared to the design of the Figure 3 consists in the curvature of the pressure side 30 of the guide vane in the rear region 320. While this curvature in the Figure 3 is at least approximately concave, it is in the embodiment of the Figure 4 Convex, so that the rear area 320 forms a portion of the convex pressure side contour 33 and contributes to the latter. The maximum M of the convex pressure side contour 33 is, however, in front of the constant passage section 29a in the front area 310. The convex pressure side contour 33 creates the transition from the rear area 320 of the guide vane to the front area 310 of the guide vane.

In the Figure 4 Furthermore, an additional line 40 and an additional surface 50 are shown, which are actually not present in the guide vane 23 and only serve to further clarify the solution according to the invention. Line 40 thus indicates the course of the pressure side of a guide vane designed according to the prior art, the wall of guide vane 23 adjacent to blade trailing edge 32 being essentially straight or having a slight, uniform curvature. Line 40 thus illustrates the pressure side contour of a conventional guide vane. The surface 50 illustrates a thickening, on the other hand, by realizing a convex pressure side contour 33. This thickening or provision of a convex pressure side contour 33 makes it possible, even with a loss-optimized turbine stator, the guide vanes 23 with a considerable convex curvature of the suction side 31 in the area of the narrow cross-section and / or adjacent to the narrow cross-section, to provide a constant passage section 29a within the passage 29, so that a passage widening is prevented in the case of a backburn 35.

A thickening 50 is also in the embodiment of FIG Figure 3 in front. In the exemplary embodiment of FIG Figure 3 however, a different shape and does not run Overall convex, but also has a convex section in the transition from the rear area 320 to the front area 310. When designing the Figure 4 the thickening 50 is completely formed by the convex pressure side contour 33.

Another peculiarity of the design of the Figure 4 consists in that a concave region 34 is provided adjacent to the convex region 33 on the pressure side 30 of the guide vane 23. This leads to a further optimization of the surface pressure distribution on the blade surface.

The Figure 5 shows a comparison of the configuration according to the prior art, as this in the Figure 2 is shown (left half of Figure 5 ) and an embodiment of the invention according to the Figure 4 . The contours of the pressure side 30 provided according to the invention result in the advantages described above. This is particularly evident from the comparative representation of the static surface pressures Figure 6 evident. The normalized chord length of 0.0 corresponds to the position of the blade leading edge, the normalized chord length of 1.0 corresponds to the position of the blade trailing edge.

The top half of the picture Fig. 6 shows the geometric design according to the prior art ( Fig. 5 left) proper surface pressure distribution. The lower half of the picture Fig. 6 shows the configuration according to the invention ( Fig. 5 right) proper surface distribution. The advantageous pressure curve resulting according to the invention on the suction side ( Fig. 6 below), which can be implemented without violating the burn-back criterion. The S-stroke of the pressure curve on the pressure side in the area of the blade trailing edge with the chord length 0.7 to 1.0 ( Fig. 6 below) results from the contouring of the printing side according to the invention in order to comply with the burn-back criterion.

Reference symbol list:

1

Engine axis

10th

Gas turbine engine / core engine

11

Air intake

12th

fan

13

Medium pressure compressor

14

High pressure compressor

15

Combustion chamber

16

High pressure turbine

17th

Medium pressure turbine

18th

Low pressure turbine

19th

Exhaust nozzle

20th

Guide vanes

21

Core engine housing

22

Compressor blades

23

Turbine guide vanes

24th

Turbine blades

26

Compressor drum or disk

27

Turbine rotor hub

28

Outlet cone

29

passage

29a

constant passage section

30th

Printed page

310

front print area of the print page

320

rear area on the print side

31

Suction side

32

Blade trailing edge

33

convex pressure side contour / convex area

34

Concave area

35

Burn back

36

Narrow cross section / exit area passage

37

Passage cross section

38

Passage entrance area

40

The wall of the conventional guide vane

50

Thickening

d

Profile thickness

M

Maximum of the convex pressure side contour

Claims (11)

1. Turbine guide wheel of a gas turbine, having multiple guide vanes (23) arranged spaced apart around the circumference, wherein

   - each guide vane (23) has a suction side (31) and a pressure side (30),

   - two adjacent guide vanes (23) form, in each case between the suction side (31) of one guide vane (23) and the pressure side (30) of the other guide vane and proceeding from the vane trailing edge (32), a passage (29), and

   - each guide vane (23) has a convex pressure-side contour (33) on the pressure side (30),

   characterized in that

   - the passage comprises a constant passage section (29a) in which the passage (29) has a substantially constant passage cross section (37),

   - the constant passage section (29a) has an entry region (38) and, on the vane trailing edge (32), an exit region in the form of a narrow cross section (36) of the passage,

   - a substantially constant passage cross section (37) is present if the passage cross section (37) differs by no more than 5% from the narrow cross section (36) in the region of the vane trailing edge (32),

   - each guide vane (23) forms on the pressure side a rear region (320), which, proceeding from the vane trailing edge (32), extends as far as the entry region (38) of the constant passage section (29a) in a manner adjacent to the constant passage section (29a), and forms on the pressure side a front region (310), which is formed upstream of the rear region (320), and

   - the convex pressure-side contour (33) establishes a transition from the rear region (320) of the guide vane (23) to the front region (310) of the guide vane (23).
2. Turbine guide wheel according to Claim 1, characterized in that, in the direction of the vane trailing edge (32) prior the rear region (320) of the guide vane (23), the profile thickness (d) of the guide vanes (23) increases, is constant, or decreases to a lesser extent than in the rear region (320) of the guide vane (23).
3. Turbine guide wheel according to Claim 1 or 2, characterized in that the convex pressure-side contour (33), at or upstream of the entry region (38), forms a maximum (M) in the constant passage cross section (29a).
4. Turbine guide wheel according to one of the preceding claims, characterized in that the convex pressure-side contour (33) on the pressure side (30) of the guide vanes (23) is formed predominantly or completely in the front region (310) of the guide vane (23).
5. Turbine guide wheel according to one of the preceding claims, characterized in that the convex pressure-side contour (33) is also formed partly in the rear region (320) of the guide vane (23).
6. Turbine guide wheel according to one of the preceding claims, characterized in that, proceeding from the vane trailing edge (32), the guide vane (23) is provided with a concave region (34) adjacent to the convex pressure-side contour (33).
7. Turbine guide wheel according to one of the preceding claims, characterized in that the guide vanes (23) have the convex pressure-side contour (33) at least over a sub-region of the vane height.
8. Turbine guide wheel according to one of the preceding claims, characterized in that the turbine guide wheel is formed in a manner optimized with respect to loss, and the guide vanes (23) have on the suction side (31) a highly convex curvature in the region of the narrow cross section and/or adjacent to the narrow cross section.
9. Turbine guide wheel according to one of the preceding claims, characterized in that the constant passage section (29a) extends over a chord length which lies in the range between 5% and 40% of the total chord length.
10. Turbine guide wheel according to one of the preceding claims, characterized in that this is a high-pressure turbine guide wheel.
11. Use of the turbine guide wheel according to one of the preceding claims in a gas turbine engine (10).

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