HEAT SHUTTER ELEMENT WITH SEAL

Description

[0001] The invention relates to a heat shield element of a combustion chamber, with a seal by means of which an uncontrolled flow of cooling air is to be prevented.

[0002] Heat shield elements are frequently used in combustion chambers, particularly in gas turbines. These elements are available in both ceramic and metallic materials. Their primary function is to equip the interior of the combustion chamber with a robust yet replaceable component. To ensure maximum service life, the heat shield elements are typically cooled with cooling air. This cooling air is directed to the underside of the heat shield elements, while preventing uncontrolled airflow between the elements and into the combustion chamber.

[0003] For this purpose, some embodiments employ seals which are inserted into grooves on circumferential ribs on the underside of the heat shield elements. As a rule, the seals have a rectangular cross-section and extend essentially over the length or width of the heat shield elements. To achieve the seal, the seal rests on a supporting structure, thus acting as the seal.

[0004] Although the known seals can generally achieve a sufficiently reliable seal between the heat shield elements and the supporting structure, a disadvantage has been found in that the required flow of cooling air is sometimes reduced too much. Furthermore, it has proven detrimental if the gap between two adjacent heat shield elements is not adequately supplied with cooling air.

[0005] A simple solution is to omit the gasket section by section or completely and improve the fit between the heat shield element and the supporting structure. With a reduced gap or better contact between the heat shield element and the supporting structure, the airflow is reduced while still allowing sufficient cooling. The problem lies in thermal deformation under different operating conditions, which can cause the airflow to be temporarily too high or too low.

[0006] To solve this problem, it is known from the prior art to use seals and to introduce bores into the circumferential webs of the heat shield elements in order to ensure a targeted flow of cooling air into the gap.

[0007] The problem of targeted cooling is addressed in US2009 / 0202956A1. The combustion chamber is lined on the inside with heat shield elements, each of which is attached to the underside by longitudinally extending brackets. Cooling air is directed to a chamber within the bracket, and from there, the cooling air is channeled through numerous cooling air holes to the underside of the heat shield elements.

[0008] Furthermore, US2015 / 354818A1 shows another solution for targeted cooling airflow. In this solution, a sealing element runs along the underside edge of a heat shield element. The sealing element is provided with multiple cutouts, ensuring a free passage for cooling air.

[0009] Although there is a proven embodiment for the heat shield elements with the seals, the task is still to develop a more cost-effective embodiment in which, in particular, the amount of cooling air can be adjusted as precisely as possible.

[0010] The problem is solved by a heat shield element according to the invention and the features of claim 1. A heat shield according to the invention is specified in claim 11. Advantageous embodiments are the subject of the dependent claims.

[0011] The heat shield element of this type is primarily used in a heat shield. A heat shield element has a hot side facing the interior of a combustion chamber and an opposing cold side facing a supporting structure of the combustion chamber. Furthermore, the heat shield element has a sealing groove extending longitudinally. Whether this longitudinal direction coincides with or runs perpendicular to a longitudinal axis of the combustion chamber is irrelevant. The sealing groove must be open on the cold side.

[0012] The design incorporates a seal inserted into the sealing groove. The seal thus runs along the longitudinal direction and therefore has a hot side and an opposing cold side. The surface of the seal located on the hot side is referred to as the groove surface. A contact surface is located on the opposing cold side. Opposing flanks extend from the contact surface to the groove surface in the direction from the cold side to the hot side.

[0013] Provided that the supporting structure and the heat shield element are essentially flat, the seal can sometimes be omitted simply, eliminating the need for a complex solution. Therefore, the invention is particularly useful when the usable surface and the opposing contact surface are curved.

[0014] Furthermore, the seal has a sealing length from one end to the opposite end. The distance between the opposing side faces defines the seal width. The distance from the groove surface to the contact surface defines the seal height, depending on the respective position along the seal length.

[0015] For the seal, a nominal height is defined as the nominal distance from the groove surface to the contact surface. It is essential that the seal height closely matches the nominal height. This is considered to be the case if, over at least 80% of the seal length, the seal height deviates from the nominal height by no more than 10%.

[0016] It is necessary that the gasket mounted on the heat shield element, at room temperature – before being installed on a support structure – rests only on the groove base of the gasket groove at its two opposing end sections, while in the area between the end sections there is a gap between the groove surface and the groove base. This creates a defined distance from the contact surface to the hot surface of the heat shield element in the area of ​​the end sections, whereby the distance from the contact surface to the hot surface in the area between the end sections can adjust during installation on a support structure due to the intended gap between the groove surface and the groove base.

[0017] The cost savings according to the invention are achieved by providing the seal with recesses. These are arranged on the cold side and extend along the longitudinal direction. The recesses penetrate the seal from the contact surface towards the hot side. Accordingly, the recesses represent a reduction in material from the regular sealing profile between the two side flanks. To ensure the necessary cooling airflow through the recesses, it is further provided that several recesses, offset from each other, are arranged on the cold side.

[0018] Due to the cutouts, the seal can no longer rest on a supporting structure along its entire length. However, the contact area is still defined as the area that would exist without the cutouts, i.e., the entire theoretical area on the cold side over the entire length of the seal.

[0019] To achieve a beneficial effect from the cutouts, they must extend along the longitudinal direction for a length of at least 0.1 times the seal length. This is determined by adding the individual lengths of the existing cutouts. However, the cutouts should not be too long; their total length should not exceed 40% of the seal length.

[0020] The cutouts create a virtually leaky seal, eliminating the need to drill holes in the heat shield element. One might be tempted to shape the seal on the cold side unevenly and inconsistently with the supporting structure. However, this would make predicting the cooling airflow almost impossible. In contrast, the targeted placement of the cutouts allows for precise control of the desired cooling airflow.

[0021] The seal is preferably made of a metallic material. This ensures that the necessary temperature resistance and durability in the intended use of a heat shield element can be achieved while maintaining elastic properties.

[0022] Cost-effective manufacturing and advantageous adaptation of the seal to the sealing groove are achieved when the seal has a constant sealing width. This ensures that the two side flanks run parallel to each other.

[0023] If the sealing groove runs in a straight line when viewed from above on the cold side, it is advantageous if the two side flanks are flat.

[0024] It is also advantageous if the total length of the cutouts extends over at least 20% of the seal length. Conversely, it is advantageous if the total length of the cutouts is at most 0.3 times the seal length.

[0025] To enable the desired cooling airflow through the recesses, it is advantageous if the recesses have a depth, measured from the contact surface, of at least 0.05 times the gasket height at the same location. It is particularly advantageous if the recess depth is at least 10% of the gasket height.

[0026] In contrast, to ensure the actual sealing effect and the long-term stability of the seal, it is advantageous if the depth is a maximum of 40% of the seal height. It is particularly advantageous if the depth of the recesses is at most 0.2 times the seal height.

[0027] Furthermore, it is also advantageous if the seal height decreases towards the respective end at at least one end section, and particularly preferably at both opposite end sections. The seal height at the end of the seal should preferably be less than 50% of the nominal height. Depending on the intended placement of the contact surface on a support structure, it is further advantageous if the reduction of the seal height on the hot side is achieved by a corresponding approximation of the groove surface to the contact surface. The change in seal height can be achieved in steps or by a chamfer. However, an arc-shaped transition from the approximate nominal height to the reduced height at the end of the seal is advantageous.

[0028] To ensure the most precise possible fit of the seal into the sealing groove, with the desired contact surface on a supporting structure and taking thermal stress into account, it is advantageous to have a raised section on the hot side of at least one end section, and particularly advantageously on both end sections. A relatively small raised section is sufficient to enable a defined contact on the hot side. Therefore, it is advantageous if the raised section has a height relative to the adjacent groove surface of at least 0.01 times the nominal height (i.e., 1% of the nominal height) and a maximum of 0.1 times the nominal height (i.e., 10% of the nominal height). This allows for targeted and thus defined contact by means of the raised section, provided the sealing groove is uniformly shaped.

[0029] In a further embodiment, a recess is advantageously arranged on the hot side of an end section. This recess has a depth of at least 5% and a maximum of 20% of the nominal height. The recess can be used to fix the seal longitudinally. If a protrusion is present on the same end section, the recess is preferably located between the end and the protrusion.

[0030] At least it is particularly advantageous if the seal of the heat shield element has a protrusion on both opposite end sections on the hot side and rests on the groove base of the sealing groove with this protrusion - and preferably only with this.

[0031] A heat shield element according to the invention, as described above, enables the formation of a heat shield according to the invention. The heat shield comprises a support structure on which several heat shield elements are mounted, with the contact surfaces of the respective seals resting on the support structure. This creates a free cooling air cross-section along the length of the recesses.

[0032] Complete contact of the sealing surfaces of the respective seals with the supporting structure can be advantageously achieved by elastically deforming the seals during the installation of the heat shield element. The seal's sealing surface is shaped in such a way that, during installation, the distance between the groove surface and the groove base in the area between the end sections is reduced compared to the stress-free position before installation. This advantageously ensures that the desired cooling airflow can pass through the openings without any significant additional leakage.

[0033] To adjust the cooling airflow, it is also advantageous if, in the assembled state, a gap exists between the heat shield element (without a seal) and the supporting structure, at least in the area of ​​the cutouts. This ensures a free cross-section under the heat shield elements along the cutouts.

[0034] The following figures sketch an exemplary embodiment of a seal and a heat shield element. They show: Fig. 1 an exemplary embodiment for a seal of a heat shield element according to the invention; Fig. 2 an exemplary embodiment for a heat shield element according to the invention; Fig. 3 the seal according to Fig. 1 in side view; Fig. 4 the seal according to Fig. 1 in top view; Fig. 5 a detailed view of the first end section of the seal; Fig. 6 a cross-section through the heat shield element in detail in the area of ​​the seal; Fig. 7 a view as before with the heat shield element mounted on a support structure; Fig. 8 a longitudinal section through the heat shield element in the area of ​​the seal; Fig. 9 a view as before with the heat shield element mounted on the support structure; Fig. 10 a view as before Fig. 9 with thermal deformation of the heat shield element.

[0035] In the Fig. 1 An exemplary embodiment of a seal 11 of a heat shield element 01 according to the invention is sketched in a perspective view of the contact surface 14. The seal extends along a longitudinal direction from one end to the opposite end. An arc-shaped form is visible, resulting from the shape of the combustion chamber and thus of the heat shield element 01. The narrow visible side with the arc-shaped form is the contact surface 14. The flat side flank 19 is visible perpendicular to this. However, the seal height 21 decreases significantly towards the end at the two opposite end sections 15, 16.

[0036] Essential for the embodiment according to the invention is the presence of several recesses 12, which also extend section by section along the longitudinal direction and here starting from the contact surface 14 into the seal 11.

[0037] In the following Fig. 2 Figure 1 shows an exemplary heat shield element 01 according to the invention in a perspective view. The heat shield element 01 is shown with the cold side 04, while the hot side 03 is located opposite it, though not visible. The hot side 03 faces the interior of the combustion chamber. It can also be seen that the heat shield element 01 has a circumferential web extending from the hot side 03 to the cold side 04. The webs have a sealing groove 05 extending longitudinally along two opposite edges.

[0038] Here shown is seal 11 - as in Fig. 1 The seal shown is inserted in the sealing groove on the left side of the illustration. The opposite sealing groove 05 on the right side of the illustration also provides for the use of a corresponding seal with recesses. Furthermore, it may be provided that a seal with recesses in a transverse web is used.

[0039] In the Figuren 3, 4 and 5 The seal will be replaced again Fig. 1 in a side view on a side edge 19 - Fig. 3 - and in a top view of the groove surface 13, i.e. from the hot side 03 - Fig. 4 - and a detailed view of a first end section 15 of the seal 11 - Fig. 5 .

[0040] The seal 11 extends along a longitudinal direction and has an arc-shaped profile. On the hot side, there is a groove 13, which, in the assembled state, is located in the seal groove 05. Opposite this is the contact surface 14, which rests on a support structure 09 when the heat shield element 01 is mounted. The distance between the functional surface 13 and the contact surface 14 forms the seal height 21. This height is essentially constant except at the two end sections 15 and 16 and corresponds to the nominal height of the seal 11. The two opposing side flanks 19 are flat, so that the seal 01 has a constant sealing width.

[0041] The recesses 12, located on the cold side 04 and extending from the contact surface 14 towards the hot side 03, are again visible. These recesses 12 have a depth 22, which in this embodiment corresponds approximately to 0.3 times the gasket height 21. However, a design with a slightly shallower depth than shown here is advantageous.

[0042] Furthermore, the different shape of the end sections 15 and 16 can be seen. Here, the distance from the usable surface 13 to the contact surface 14 decreases towards the end, so that the height at the two opposite ends of the seal is reduced to approximately 0.3 times the nominal height - essentially corresponding to the seal height 21 in the course between the end sections 15, 16.

[0043] It can also be seen that on the hot side 03, a protrusion 17 is located at each of the two end sections 15, 16. The height of the protrusion 17 compared to the adjacent groove surface 13 is relatively small. The function of the protrusions 17 is, in particular, to create a defined contact surface on a groove base 06 of the sealing groove 05.

[0044] On the first end section 15, there are also two recesses 18 on the hot side 03. These 18 enable the seal 11 to be fixed to the heat shield element 01 in the longitudinal direction.

[0045] In the Figuren 6 and 7This is a detailed cross-sectional view of the heat shield element 01 with the seal 11. The heat shield element 01 is visible with the web shown here, which extends from the hot side to the cold side 04 and has the sealing groove 05 on the cold side 04. The seal 11 is located in the sealing groove 05, with the recess 12 being located on the cold side 04.

[0046] In the Fig. 6 The figure shows the stress-free installation of the seal 11 on the heat shield element 01, with a larger clearance between the groove surface 13 and the groove base 06 of the seal groove 05. In contrast, in the Fig. 7 The installation on a supporting structure 09 is sketched, so that the distance between the groove base 06 and the groove surface 13 is reduced.

[0047] It can also be seen that there is a gap 10 between the heat shield element 01 and the support structure 09, with the recess 12 also allowing a free passage for a cooling airflow.

[0048] The following further demonstrate this Figuren 8-10 The arrangement of the seal 11 on the heat shield element 01 in a longitudinal section, i.e., along the longitudinal direction. As can be seen from the Fig. 8 As can be seen, the seal 11 is received in the sealing groove 05. The seal 11, with its two protrusions 17 located at the end sections 15 and 16, rests against the groove base 06 of the sealing groove 05. In contrast, there is a gap between the end sections 15 and 16, between the groove surface 13 and the groove base 06.

[0049] The installation of the heat shield element 01 with the seal 11 on the support structure 09 of a combustion chamber deforms the seal 11 - see Fig. 9 - by reducing the distance from the groove surface 13 to the groove base 06.

[0050] If thermal deformation occurs, it is possible that the heat shield element 01 may move away from the support structure 09 in the middle. Nevertheless, the seal 11 rests with its contact surface 11 on the support structure 09, whereby the distance from the groove surface 13 to the groove base 06 increases again – see Fig. 10 .

[0051] Essential to the invention are the recesses 12 in the seal 11, which ensure a controlled cooling airflow largely independent of the deformation of the heat shield element 01.

[0052] between the end sections 15 and 16 a free space between the groove surface 13 and the groove base 06.

[0053] The installation of the heat shield element 01 with the seal 11 on the support structure 09 of a combustion chamber deforms the seal 11 - see Fig. 9 - by reducing the distance from the groove surface 13 to the groove base 06.

[0054] If thermal deformation occurs, it is possible that the heat shield element 01 may move away from the support structure 09 in the middle. Nevertheless, the seal 11 rests with its contact surface 11 on the support structure 09, whereby the distance from the groove surface 13 to the groove base 06 increases again – see Fig. 10 .

[0055] Essential to the invention are the recesses 12 in the seal 11, which ensure a controlled cooling airflow largely independent of the deformation of the heat shield element 01.

Claims

1. A heat shield element (01) for use in a heat shield of a combustion chamber with a hot side (03) and an opposing cold side (04) which (01) has at least one seal groove (05) extending in a longitudinal direction open toward the cold side (04) in which (05) a seal (11) is arranged which (11) extends along a longitudinal direction over a seal length and has an arched groove surface (13) on a hot side (03) and an arched abutment surface (14) and opposing side flanks (19) extending from the groove surface (13) to the abutment surface (14) on an opposing cold side (04), wherein a rated height is given as a nominal distance and a seal height (21) is given as a local distance from the groove surface (13) to the abutment surface (14), wherein the seal height (21) corresponds to the rated height + / - 10% over at least 80% of the seal length, disregarding recesses (12), wherein at least at room temperature, the seal (11) rests on a groove bottom (06) of the seal groove (05) at both opposing end portions (15, 16) and a free space is present between the groove bottom (06) and the groove surface (13) in the region between the two end portions (15, 16), and wherein the seal (11) has multiple recesses (12) spaced apart from one another which (12) extend starting from the abutment surface (14) toward the hot side (03) in portions along the longitudinal direction in total over at least 10% and over a maximum of 40% of the seal length.

2. The heat shield element (01) according to claim 1, wherein the seal (11) consists of a metallic material.

3. The heat shield element (01) according to claim 1 or 2, wherein the side flanks (19) are parallel.

4. The heat shield element (01) according to any one of claims 1 to 3, wherein the groove surface is convexly arched and the abutment surface (14) is concavely arched.

5. The heat shield element (01) according to any one of claims 1 to 4, wherein the recesses (12) extend along the longitudinal direction in total over at least 20% and / or a maximum of 30% of the seal length.

6. The heat shield element (01) according to any one of claims 1 to 5, wherein the recesses (12) have a depth (22) of at least 5% and a maximum of 40% of the seal height (21).

7. The heat shield element (01) according to any one of claims 1 to 6, wherein at one or at both end portions (15, 16), the seal height (21) on the hot side (03) decreases toward the respective end to less than 50% of the rated height.

8. The heat shield element (01) according to any one of claims 1 to 7, wherein a projection (17) is arranged at one or at both end portions (15, 16) on the hot side (03) spaced apart from the respective end which (17) has a height of at least 1% and a maximum of 10% of the rated height.

9. The heat shield element (01) according to any one of claims 1 to 8, wherein at least one depression (18) is present at an end portion (15) on the hot side (03) spaced apart from the end which (18) has a depth of at least 5% and a maximum of 20% of the rated height.

10. The heat shield element (01) according to claim 9, wherein at least one depression (18) is present at an end portion (15) on the hot side (03) spaced apart from the end between the end and the projection (17).

11. The heat shield element (01) according to any one of claims 1 to 10, wherein the seal (11) has a projection (17) of a height of at least 1% and a maximum of 10% of the rated height at both end portions (15, 16) on the hot side (03) spaced apart from the respective end, wherein at least at room temperature, the seal (11) rests on the groove bottom (06) of the seal groove (05) at both opposing end portions (15, 16) by means of the projections (17).

12. A heat shield for use in a combustion chamber of a gas turbine, comprising a support structure (09) and a multitude of heat shield elements (01) with seal (11) according to any one of the preceding claims, wherein the seals (11) rest on the support structure (09) by means of the abutment surface (14).

13. The heat shield according to claim 12, wherein at least at room temperature, the seal is elastically deformed and the distance from the groove bottom (06) to the groove surface (13) is reduced as compared to stress-free placement.

14. The heat shield according to claim 12 or 13, wherein a gap (10) is given between the heat shield element (01) itself and the support structure (09) at least in the region of the recesses (12).