Gas turbine with outlet guide grid arranged in the transition duct

Abstract

A gas turbine with a low-pressure compressor section and a high-pressure compressor section, with an annular transition channel connecting the low-pressure compressor section to the high-pressure compressor section, and with support struts (30) arranged in the transition channel (80), wherein an outlet guide vane (10) with a plurality of profiled blades (50, 52, 54, 56) arranged side by side in the circumferential direction is arranged at an outlet of the low-pressure compressor section, wherein the blades (50, 52, 54, 56) are each arranged at a staggered angle, characterized in that in the projection region (20) of a support strut (30) formed upstream in the flow direction, at least one first blade (52) of the outlet guide vane (10) and one second blade (54) of the outlet guide vane (10) are arranged upstream of the respective support strut (30),wherein the second blade (54) is arranged circumferentially adjacent to the first blade (52) and wherein the first blade (52) is arranged at a smaller stagger angle β1 than the stagger angle β2 of the second blade (54), so that the leading edges (52b, 54b) of the first and second blades (52, 54) have a smaller distance from each other in the circumferential direction than the trailing edges (52a, 54a) of the first and second blades (52, 54).,

Description

[0001] The present invention relates to a gas turbine according to the preamble of claim 1.

[0002] Compressor systems in gas turbines, such as aircraft gas turbines, are operated at a fixed distance from the surge limit in order to ensure safe operation.

[0003] The compressor system in aircraft gas turbines consists of a low-pressure compressor and a high-pressure compressor, which are connected via a transition duct. Large support struts arranged in the transition duct pose a problem. Due to their function of transmitting power between the engine and the aircraft, the support struts must be relatively thick. This leads to the formation of a potential field in front of the strut, in which the flow accumulates at the leading edge of the support strut, resulting in an increase in the static pressure in front of the strut. This local change in pressure also propagates against the direction of flow and results in the upstream grilles or rotors being subjected to higher aerodynamic loads than originally intended.Therefore, the outlet guide vanes and the last rotor of the low-pressure compressor are placed as far upstream as possible so that the influence of the pressure change in front of the strut on the rotor is as small as possible, thus ensuring as far as possible that the rotor is exposed to a homogeneous back pressure and that all rotor passages are subjected to essentially the same load.

[0004] In Fig. 1 A row of blades 5 of an outlet guide vane 1 is shown schematically. The blades 5 are arranged with a uniform stagger angle β and uniform distances a of the blade trailing edges 5a in the circumferential direction. The static pressure (in Fig. 1 shown schematically at the appropriate point) is increased in front of the support strut leading edge 3a of the support strut 3 and continues through the outlet guide vane 1 in the upstream direction, so that the static pressure in the area 7 in front of the outlet guide vane 1 is also increased at the appropriate point.

[0005] However, in order to produce compact gas turbines, it is desirable to be able to move the outlet guide vanes closer to the support struts of the transition channel.

[0006] It is therefore an object of the present invention to provide a gas turbine of the type mentioned at the outset in which the influence of the support struts of the transition channel on the outlet guide vane or the rotor of the low-pressure compressor located upstream thereof is small.

[0007] The invention is defined by the features of claim 1.

[0008] In the gas turbine according to the invention with a low-pressure compressor section and a high-pressure compressor section, with an annular transition channel connecting the low-pressure compressor section and the high-pressure compressor section, and with support struts arranged in the transition channel, wherein an outlet guide vane with a plurality of profiled blades arranged next to one another in the circumferential direction is arranged at an outlet of the low-pressure compressor section, wherein the blades are each arranged at a staggered angle, it is provided that in each case in the projection region of a support strut formed upstream in the flow direction, at least one first blade of the outlet guide vane and a second blade of the outlet guide vane are arranged upstream of the respective support strut,wherein the second blade is arranged circumferentially adjacent to the first blade and wherein the first blade is arranged at a smaller stagger angle β 1 than the stagger angle β 2 of the second blade, so that the leading edges of the first and second blades have a smaller distance from each other in the circumferential direction than the trailing edges of the first and second blades.,

[0009] In contrast to conventional outlet guide vanes, in which all blades are arranged at the same stagger angle, the invention provides that the outlet guide vanes located in front of the support strut have different stagger angles β 1 , β 2 , so that a passage is formed between the first and second blades that widens in the direction of flow. Furthermore, the passage inlet between the first and second blades is smaller than that of the neighboring blades, so that a smaller proportion of the flow flows between the first and second blades compared to the other passages. By widening the passage formed between the first and second blades, the flow is slowed, thereby reducing the pressure.This ensures that the static pressure in front of the leading edge of the support strut is lower, thus minimizing the effect of the static pressure in front of the support strut on the upstream area, and especially the area in the flow direction in front of the outlet guide vane. This ensures that the last rotor of the low-pressure compressor is exposed to a relatively uniform static pressure.

[0010] It can also be provided that in the projection area of ​​the respective support strut formed upstream in the flow direction, a third blade of the outlet guide vane is arranged upstream of the support strut, which is arranged circumferentially next to the second blade on the side applied by the first blade, wherein the third blade is arranged at a greater stagger angle β 3 than the stagger angle β 2 of the second blade, so that the leading edges of the second and third blades have a smaller distance in the circumferential direction than the trailing edges of the second and third blades. In other words: in the upstream projection area of ​​a support strut, three blades, the first, the second and the third blade, can be arranged, wherein the passages formed between the blades widen in the flow direction.Just as in the passage between the first and second blades, in the passage between the second and third blades the flow is slowed down so that the pressure drops and there is therefore less static pressure from the flow hitting the strut leading edge between the second and third blades.

[0011] The design of the first and second blades or of the first and second and third blades is further selected such that the flow around the leading edge of the support struts takes place in an advantageous manner.

[0012] The first, the second, or the first, second, and third blades can have the same curvature and / or profile. In particular, it can be provided that all blades of the outlet guide vane have the same curvature and / or profile. In other words, it can be provided that the blades of the outlet guide vane have the same shape and differ only in their spacing and stagger angle. This results in a comparatively simple design of the outlet guide vane.

[0013] At least individual blades of the outlet guide vane, which are arranged outside the projection areas of the support struts formed upstream in the flow direction, can have stagger angles β i adapted to the stagger angles β 1 and β 2 of the first and second blades or to the stagger angles β 1 and β 3 of the first and third blades. In other words: the blades that are arranged between the areas of the first and second blade or the first and second and third blades and are thus not in the projection area of ​​a support strut, have a stagger angle that is adapted to the stagger angles of the first, second or third blade.For example, in an outlet guide vane, a region may be formed between a third vane arranged in front of a first support strut and a first vane arranged in front of a further support strut, wherein the vanes in this region which are closer to the third vane have stagger angles which approximate the stagger angle β 3 , whereas the vanes which are closer to the first vane have stagger angles which approximate the stagger angle β 1 .

[0014] According to the invention, it can be provided that the blades which are arranged outside the projection areas formed upstream in the flow direction of two adjacent support struts between the first blade arranged upstream of one of the adjacent support struts and the second blade arranged upstream of the other of the adjacent support struts have stagger angles β i which are interpolated between the stagger angle β 1 of the first blade arranged upstream of one of the adjacent support struts and the stagger angle β 2 of the second blade arranged upstream of the other of the adjacent support struts.

[0015] It can also be provided that the blades which are arranged outside the projection areas formed upstream in the flow direction of two adjacent support struts between the first blade arranged upstream of one of the adjacent support struts and the third blade arranged upstream of the other of the adjacent support struts have stagger angles β i which are interpolated between the stagger angle β 1 of the first blade arranged upstream of one of the adjacent support struts and the stagger angle β 3 of the third blade arranged upstream of the other of the adjacent support struts.

[0016] Thus, the stagger angles β i of the blades arranged in the region between two adjacent support struts can be interpolated between the stagger angles β 1 and β 2 of the adjacent first and second blades or the stagger angles β 1 and β 3 of the adjacent first and third blades.

[0017] This avoids large jumps in the stagger angles in the areas between two support struts, thereby reducing irregularities in the static pressures.

[0018] The distance between the trailing edges of the blades of the outlet guide vane array that are arranged outside the projection areas of the support struts formed upstream in the flow direction may be greater than the distance between the trailing edges of the first and second blades or the distance between the trailing edges of the second and third blades. In particular, the distances between the leading edges of the blades of the outlet guide vane array that are arranged outside the projection areas of the support struts formed upstream in the flow direction may also be greater than the distances between the leading edges of the first and second blades or the distances between the trailing edges of the second and third blades.In other words, the passages between the vanes of the outlet guide vane located outside the upstream projection areas of the support struts are thus wider than the passages formed by the first and second or the second and third vanes. This allows the flow in these areas to be guided advantageously.

[0019] It can be provided that distances between the trailing edges of blades which are arranged outside the projection areas of two adjacent support struts formed upstream in the flow direction and are arranged between the first blade arranged upstream of one of the adjacent support struts and the second blade arranged upstream of the other of the adjacent support struts become larger in the circumferential direction towards the center between the first and the second blade.

[0020] It can be provided that distances between the trailing edges of blades which are arranged outside the projection areas of two adjacent support struts formed upstream in the flow direction and are arranged between the first blade arranged upstream in front of one of the adjacent support struts and the third blade arranged upstream in front of the other of the adjacent support struts become larger in the circumferential direction towards the center between the first and the third blade.

[0021] In a region of the outlet guide vane that is arranged circumferentially between a region with a first and second blade or a first, second, and third blade and a region with a first and second blade or a first, second, and third blade, it is thus provided that the distances of the trailing edge of the blades from a region of the first and with the first and second blade or with the first, second, and third blade increase with increasing distance from this region and then decrease again towards the next region with the first and second blade or with the first, second, and third blade. This avoids major changes in neighboring blades and the passages formed by them, so that the flow remains comparatively uniform.

[0022] The invention is explained in more detail below with reference to the following figures. Fig. 1 is a schematic representation of an outlet guide vane according to a conventional arrangement of the blades, Fig. 2 is an outlet guide vane of a gas turbine according to the invention with two blades arranged in a modified manner in front of a support strut, and Fig. 3 is a schematic representation of an outlet guide vane of a gas turbine according to the invention with three blades arranged in front of a support strut.

[0023] In Fig. 1 A conventional outlet guide vane 1 of a gas turbine is shown schematically. As previously described, the blades 5 of the conventional outlet guide vane are arranged with the same stagger angle β and the same spacing a.

[0024] In Fig. 1The static pressures are graphically represented in the corresponding sections. Due to the support strut leading edge 3a, there is an increased static pressure in the area behind the outlet guide vane in front of the support strut 3. This also causes an increased static pressure in the area 7 in front of the outlet guide vane 1, so that this static pressure is also applied to a rotor of the low-pressure compressor.

[0025] In the Fig. 2 and 3 Two exemplary embodiments of outlet guide vanes 10 according to the invention are shown. The outlet guide vane 10 is arranged at an outlet 70 of a low-pressure compressor section of the gas turbine upstream of an annular transition channel 80. Support struts 30 are arranged in the transition channel 80.

[0026] The outlet guide vane 10 has a plurality of profiled blades 50, 52, 54 arranged next to one another in the circumferential direction, each of which is arranged at a staggered angle β 1 , β 2 , β i .

[0027] In a projection area 20 of the support strut 30, which is formed upstream, Fig. 1In the exemplary embodiment shown, a first blade 52 and a second blade 54 are arranged. The first blade 52 is arranged at a smaller stagger angle β 1 than the stagger angle β 2 of the second blade 54. As a result, the leading edges 52b, 54b of the first and second blades 52, 54 are arranged at a smaller distance a 1 in the circumferential direction than the trailing edges 52a, 54a of the first and second blades 52, 54. The passage formed between the first and second blades 52, 54 thus widens in the flow direction, so that the static pressure of the flow in this passage decreases in the flow direction. As a result, the static pressure in front of the support strut leading edge 30a of the support strut 30 is lower compared to the conventional arrangement. At the same time, an advantageous flow around the support strut leading edge 30a is achieved, as indicated by the corresponding arrows.

[0028] In the Fig. 3In the exemplary embodiment shown, in addition to the first and second blades 52, 54, a third blade 56 is also located in the projection area 20 of the support strut 30. The third blade 56 is arranged on the side of the second blade 54 facing away from the first blade 52 and has a larger stagger angle β 3 than the stagger angle β 2 of the second blade 54. As a result, the passage formed between the second and third blades 54, 56 is designed such that it widens in the flow direction. Also in the case of the Fig. 3 In the embodiment shown, an advantageous flow around the support strut leading edge 30a is achieved and, due to the reduction in flow velocity, a lower static pressure is achieved in the outlet guide grille 10.

[0029] The stagger angle β i of the blades 50, which are located outside the projection areas 20 of the support struts 30, are adapted to the stagger angles β 1 and β 2 of the first and second blades 52, 54 or the stagger angle β 1 and β 3 of the first and third blades 52, 56.

[0030] In the Fig. 2In the exemplary embodiment shown, for example, the stagger angles β i of the blades 50 located to the right of the projection area 20 are adapted to the stagger angle β 2 of the second blade 54, whereas the stagger angles β 1 of the blades 50 located to the left of the projection area 20 are adapted to the stagger angle β 1 of the first blade 52. For example, it can be provided that the stagger angles β i of the blades 50 arranged between a projection area 20 of a support strut 30 and the projection area 20 of an adjacent support strut 30 are interpolated, so that the stagger angle β i changes in small steps.

[0031] Furthermore, it can be provided that the distances ai of the trailing edges 50a of the blades 50 are greater than the distance ai between the trailing edges 52a and 54a of the first and second blades 52, 54 and than the distance a 2 of the trailing edges 54a, 56a of the second and third blades 54, 56. List of reference symbols

[0032] 1Conventional outlet guide vane 3Support strut 3aSupport strut leading edge 5Blade 5aBlade trailing edge 7Area 10Exit guide vane 20Projection area 30Support strut 30aSupport strut leading edge 50Blade 50aTrailing edge 52First blade 52aTrailing edge 52bLeading edge 54Second blade 54aTrailing edge 54bLeading edge 56Third blade 56aTrailing edge 56bLeading edge 70Exit 80Transition channel a 1 Distance a 2 Distance ai Distance β 1 Stagger angle β 2 Stagger angle β 3 Stagger angle ßiStagger angle

Claims

1. Gas turbine with a low-pressure compressor section and a high-pressure compressor section, with an annular transition channel (80) connecting the low-pressure compressor section to the high-pressure compressor section, and with support struts (30) arranged in the transition channel (80), wherein an outlet guide vane (10) with a plurality of profiled blades (50, 52, 54, 56) arranged side by side in the circumferential direction is arranged at an outlet of the low-pressure compressor section, wherein the blades (50, 52, 54, 56) are each arranged at a staggered angle, characterized in thatin the projection region (20) of a support strut (30) formed upstream in the flow direction, at least one first blade (52) of the outlet guide grille (10) and one second blade (54) of the outlet guide grille (10) are arranged upstream of the respective support strut (30), wherein the second blade (54) is arranged adjacent to the first blade (52) in the circumferential direction and wherein the first blade (52) is arranged at a smaller stagger angle β 1 is arranged as the stagger angle β 2 the second blade (54), so that the leading edges (52b, 54b) of the first and second blades (52, 54) have a smaller distance from one another in the circumferential direction than the trailing edges (52a, 54a) of the first and second blades (52, 54).

2. Gas turbine according to claim 1, characterized in thatin the projection region (20) of the respective support strut (30) formed upstream in the flow direction, a third blade (56) of the outlet guide vane (10) is arranged upstream of the support strut (30), which third blade (56) is arranged in the circumferential direction next to the second blade (54) on the side facing away from the first blade (52), wherein the third blade (56) is arranged at a larger stagger angle β 3 is arranged as the stagger angle β 2 of the second blade (54), so that the leading edges (54b, 56b) of the second and third blades (54, 56) have a smaller distance in the circumferential direction than the trailing edges (54a, 56a) of the second and third blades (54, 56).

3. Gas turbine according to claim 1 or 2, characterized in that the first and second blades (52, 54) or the first, second and third blades (52, 54, 56) have the same curvature and / or the same profile.

4. Gas turbine according to claim 3, characterized in that all blades (50, 52, 54, 56) of the outlet guide vane (10) have the same curvature and / or the same profile.

5. Gas turbine according to one of claims 1 to 4, characterized in that at least individual blades (50) of the outlet guide vane (10), which are arranged outside the projection areas (20) of the support struts (30) formed upstream in the flow direction, to the stagger angles β 1 and β 2 of the first and second blades (52, 54) or to the stagger angles β 1 and β 3 the first and third blades (52, 56) adapted stagger angle β i have.

6. Gas turbine according to one of the preceding claims, characterized in thatthe blades (50) which are arranged outside the projection areas (20) formed upstream in the flow direction of two adjacent support struts (30) between the first blade (52) arranged upstream of one of the adjacent support struts (30) and the second blade (54) arranged upstream of the other of the adjacent support struts (30), stagger angle β i which lie between the stagger angle β 1 the first blade (52) arranged upstream of one of the adjacent support struts (30) and the stagger angle β 2 the second blade (54) arranged upstream of the other of the adjacent support struts (30) are interpolated.

7. Gas turbine according to one of the preceding claims, characterized in thatthe blades (50) which are arranged outside the projection areas (20) of two adjacent support struts (30) formed upstream in the flow direction between the first blade (52) arranged upstream of one of the adjacent support struts (30) and the third blade (56) arranged upstream of the other of the adjacent support struts (30), stagger angle β i which lie between the stagger angle β 1 the first blade (52) arranged upstream of one of the adjacent support struts (30) and the stagger angle β 3 the third blade (56) arranged upstream of the other of the adjacent support struts (30) are interpolated.

8. Gas turbine according to one of claims 1 to 7, characterized in that the distance a ithe trailing edge (50a) of the blades (50) of the outlet guide vane (10), which are arranged outside the projection areas (20) of the support struts (30) formed upstream in the flow direction, is greater than the distance a 1 the trailing edges (52a, 54a) of the first and second blades or the distance a 2 the trailing edges (54a, 56a) of the second and third blades (54, 56).

9. Gas turbine according to claim 8, characterized in that Distances a i the trailing edges (50a) of blades (50) which are arranged outside the projection regions (20) of two adjacent support struts (30) formed upstream in the flow direction and are arranged between the first blade (52) arranged upstream of one of the adjacent support struts (30) and the second blade (54) arranged upstream of the other of the adjacent support struts (30), become larger in the circumferential direction towards the center between the first and the second blade (52, 54).

10. Gas turbine according to claim 8, characterized in that Distances a i the trailing edges (50a) of blades (50) which are arranged outside the projection regions (20) of two adjacent support struts (30) formed upstream in the flow direction and are arranged between the first blade (52) arranged upstream of one of the adjacent support struts (30) and the third blade (56) arranged upstream of the other of the adjacent support struts (30), become larger in the circumferential direction towards the center between the first and the third blade (52,56).

Images