Patent Application
20160131362
The invention relates to securing a heat shield block to a support structure, and relates to a heat shield, to a combustion chamber lined by the heat shield and to a gas turbine.
In many technical applications, heat shields which must resist hot gases at 1000 to 1600 degrees are used. Particularly gas turbines of the kind used in power-generating plants and in aircraft engines have correspondingly large surfaces to be shielded by heat shields within the combustion chambers. Because of thermal expansion and large dimensions, the heat shield must be composed of a multiplicity of individual heat shield blocks, which are generally ceramic and are secured to a support structure in a manner spaced apart by a sufficient gap. This gap gives the heat shield blocks, which can also be referred to as heat shield elements, sufficient space for thermal expansion.
A heat shield of the type in question thus comprises a support structure and a number of heat shield blocks, which are secured, in particular releasably secured, to the support structure. Each of the heat shield blocks has a cold side facing the support structure and a hot side opposite the cold side, which can be subjected to a hot medium. In at least one heat shield block, at least one recess is arranged in at least one circumferential side of the heat shield block, said circumferential side connecting the cold side to the hot side, wherein an aperture, which connects the recess to the cold side, extends in the circumferential side perpendicularly to the cold side. A securing bolt can be inserted into the aperture to secure the heat shield block to the support structure, with the result that a bolt head of the securing bolt projects at least partially into the recess. At the same time, the securing bolt passes through an angled plate in a penetration region. The angled plate comprises a first limb, which extends substantially parallel to the circumferential side, and a second limb, which extends into the recess. The two limbs adjoin each other at an angle edge. Such a method of securing the heat shield block, in particular by means of two recesses on each of two opposite circumferential sides, is particularly well-suited to securing an end block of a row of heat shield blocks arranged around the combustion chamber wall. The end blocks are also referred to as dummy blocks.
EP 1 884 713 B1 discloses a heat shield of the type in question in which the heat shield blocks are secured to the support structure in rows arranged coaxially with a longitudinal axis of a combustion chamber. In this arrangement, the heat shield blocks of one row are held by holding elements, which are inserted into a securing groove extending in the support structure, wherein the holding elements of the subsequent heat shield blocks are inserted into the securing groove after the holding elements of the preceding heat shield block have been secured, and they lock the preceding holding elements. In the case of the known heat shield, the dummy blocks are fixed on the support structure by means of a fastener that can be screwed into the support structure. On two opposite circumferential sides of the heat shield block, said sides connecting the cold side to the hot side, these dummy blocks have two recesses. In association with each of these recesses there is an aperture in the circumferential side, said aperture extending perpendicularly to the cold side and connecting the recess to the cold side. To secure the dummy block to the support structure, a securing bolt is inserted into each of the four apertures, with the result that a bolt head of the securing bolt projects into the recess. To ensure better distribution of the pressure exerted on the heat shield block by the bolt head, an angled plate is arranged underneath the bolt head. The securing bolt passes through the angled plate in a penetration region, with the result that the angled plate extends underneath the bolt head by means of a limb projecting into the recess and covers the aperture in which the securing bolt extends by means of a limb extending substantially parallel to the circumferential side. Slipping of the securing bolt out of the aperture can lead to a loss of the heat shield block. During operation, this can give rise to damage to the combustion chamber lined with the heat shield.
It is an underlying object of the invention to indicate a heat shield having at least one heat shield block of the type stated at the outset, the securing of which avoids detachment of the heat shield block from the support structure in a particularly reliable manner.
For this purpose, the angled plate comprises a reinforcing device which goes beyond the pure angular shape. The reinforcing device increases the resistance of the angled plate to bending caused by the securing bolt.
The invention is based on the realization that the securing of the heat shield block as described in the preamble can be significantly improved by developing the reliability of the angular plate. Redesign of the securing bolt, the recess, the amount of cooling air or of the entire securing concept is thus not necessary.
The invention ensures the securing of the heat shield block by means of a reinforcing device on the angled plate. This prevents displacement of the angled plate, which can result in the securing bolt slipping out of the aperture.
According to aspects of the invention, the reinforcing device does not involve a change in the material of the angled plate or a uniform increase in the thickness of the angled plate since such reinforcing devices would not go beyond the pure angular shape.
The term “angled plate” is not to be taken as restrictive as regards the choice of material for the angled plate. The term “heat shield block” is not to be taken as restrictive as regards the choice of material. The heat shield block is in particular composed of a ceramic material.
The heat shield blocks configured in accordance with the invention can be isolated heat shield blocks of the heat shield. For example, they can be merely the dummy blocks. However, it is also possible, for example, for all the heat shield blocks of the heat shield to be configured in accordance with the invention. In this case, all the heat shield blocks would be arranged on the support structure by means of at least one such securing means comprising a securing bolt and an angled plate. The recess can be a holding pocket arranged in the circumferential side, for example. According to another example, it would also be possible for the recess to be a holding groove extending along the circumferential side, into which a plurality of mutually spaced apertures open, thus allowing a plurality of securing bolts to be arranged on this side of the heat shield block.
To explain the concept of the reinforcing device according to the invention, a number of illustrative embodiments, which is not to be taken as restrictive, is given below, it also being possible to combine these with one another to give a reinforcing device according to the invention. For example, the reinforcing device can extend at least partially behind the penetration region, as seen from the angle edge, and reinforce this region, thus increasing resistance of the angled plate to bending caused by the securing bolt. In this case, the reinforcing device can be in the form of a web welded onto the second limb, for example. The web can extend parallel to the angle edge over the entire width of the second limb, for example. However, the web could also span the region behind the penetration region in the form of an arc, for example. Another illustrative embodiment of the reinforcing device can provide profiling of the angled plate, e.g. undulating profiling of the second limb. According to another illustrative embodiment of the reinforcing device, the reinforcing device can also additionally extend underneath the bolt head, for example.
It is advantageously possible to provide for at least one surface of the reinforcing device to at least partially reflect cooling air emerging at the side of the bolt head.
While the heat shield block is being subjected to hot gas, cooling air is passed through the securing bolt, for example. The cooling air flows through a cooling air duct which extends in the securing bolt and comprises at least one cooling air opening at the side of the bolt head, with the result that cooling air emerges at the side of the bolt head. According to another illustrative embodiment, the cooling air can be guided along the aperture at the side of the securing bolt shank, with the result that the cooling air emerges at the side of the bolt head in the region of the penetration region.
This configuration increases a dwell time of the cooling air in the region of the angled plate, ensuring that said plate is more effectively cooled during operation. In this case, the cooling air can impinge directly on the surface or can redirect cooling air which has already been reflected. Owing to the improved cooling of the angled plate, the configuration of the invention according to the invention increases the dimensional stability of the plate, ensuring that the angled plate has increased resistance to bending caused by the securing bolt.
The surface can be a lateral surface, facing toward the bolt head, of undulating profiling of the second limb. This illustrative embodiment of the reinforcing device combines two advantages. By virtue of the profiling, the angled plate is reinforced mechanically against deflection and, at the same time, increased cooling of the angled plate is ensured in a manner according to the invention. The surface can also be a lateral surface, facing toward the bolt head, of the first side wall described in greater detail below, of the angled side wall or of the shielding side wall of the reinforcing device.
It can also be regarded as advantageous that the reinforcing device comprises a first side wall, which is arranged in the region of the inlet opening of the recess in such a way that the first side wall at least partially closes the inlet opening of the recess.
This embodiment of the invention allows significantly improved cooling of the second limb, which is particularly at risk in respect of deflection of the angled plate. The cooling air emerging at the side of the bolt head of the securing bolt remains in the region of the recess for a relatively long period of time. The first side wall can extend along the angle edge and be welded to the latter in the form of a web, for example. According to another illustrative embodiment of the configuration of the invention, the angled plate with the first side wall can also be implemented by two plates welded to one another in a T shape, for example. However, it is also possible to arrange the first side wall on the angled plate in some other way, e.g. indirectly by means of further side walls of the reinforcing device.
An advantageous configuration of the invention can provide for the first side wall of the reinforcing device to close the inlet opening of the recess substantially completely.
In this case, the cooling effect of the reinforcing device is so good that there is no longer a need to consider the mechanical stability of the first side wall to increase the resistance of the angled plate.
Another advantageous configuration of the invention can provide for the first side wall to be arranged substantially at right angles on a second side wall of the reinforcing device. The second side wall extends along the second limb and comprises an opening in alignment with the penetration region of the second limb.
The second side wall can be arranged on the second limb by means of a material bond, for example, and holds the first side wall in the inlet opening of the recess. In other words, the angled plate is joined to a second angled plate to form the first side wall. In this arrangement, one limb of the second angled plate extends parallel to the second limb of the first angled plate and is arranged thereon. In this case, the first side wall is formed by the other limb of the second angled plate. This illustrative embodiment additionally increases the dimensional stability of the angled plate by means of the double plate layer on the second limb.
It is furthermore advantageously possible to envisage that the securing bolt comprises at least one cooling air duct, which opens at the side of the bolt head in at least one outlet opening, wherein an aperture extending as far as the circumference of the opening is arranged in the second side wall in the region of at least one outlet opening of the cooling air duct.
The at least one aperture can be in the form of a groove which ends in an outlet. Owing to impact cooling of its side walls and, in particular, impact cooling of its outlet, the aperture increases the cooling effect of the cooling air conveyed in the aperture. When the heat shield block is subjected to hot gas, this leads to improved cooling, in particular of the second side wall and of the second limb of the angled plate.
It is furthermore advantageously possible to provide for the reinforcing device to extend at least partially behind the penetration region, as seen from the angle edge, and to reinforce this region.
This advantageous configuration of the invention reinforces a region of the angled plate which is particularly narrow owing to the penetration region.
It can also be regarded as advantageous for the second limb of the angled plate or the second side wall of the reinforcing device to comprise, on its side opposite the angle edge, a side wall which is angled in the opposite direction to the angle edge, extends at least partially behind the penetration region, as seen from the angle edge, and reinforces this region.
The angled side wall increases the dwell time of cooling air in the region of the angled plate and serves simultaneously to provide mechanical reinforcement of the particularly narrow region of the angled plate behind the penetration region. This configuration of the invention can be implemented in combination with undulating profiling of the angled plate, for example, or can form the reinforcing device alone, for example. The side wall angled in the opposite direction to the angle edge can be produced by bending a corresponding part of the second limb, for example. However, the side wall can also be arranged on the second limb in some other way. The angle between the limb and the angled side wall is advantageously substantially a right angle.
To further enhance the cooling effect and hence the dimensional stability of the angled plate, provision can advantageously be made for a shielding side wall, which extends in the direction of the inlet opening of the recess, to be arranged on the angled side wall with a vertical clearance.
The shielding side wall advantageously extends substantially parallel to the second limb.
The shielding side wall can extend as far as the inlet region of the recess, for example. Depending on the vertical clearance, the shielding side wall can comprise an aperture for the bolt head or at least one opening for an assembly tool. This configuration of the invention has several advantages. The shielding side wall shields the second limb against the entry of hot gas. Moreover, a cooling air space, which is delimited by the angled side wall and the shielding side wall and into which cooling air emerging at the side of the bolt head of the securing bolt is directed back onto the angled plate, with the result that the dwell time of the cooling air in the recess is increased, is achieved. After a certain time, the cooling air flows out of the recess and enters the combustion chamber through the expansion gaps between the heat shield blocks. The longer the cooling air remains in the recess, the better is the cooling of the angled plate. Moreover, impact cooling of the heat shield block is avoided by means of the two side walls. The heat shield blocks are generally composed of a ceramic material, which tends to crack when subjected to a direct flow of cooling air. Moreover, the shape of the configuration according to the invention prevents the angled plate from being bent open by overheating or creep. The angled plate according to this configuration can furthermore be produced from a single piece by introducing a further U-shaped bend into the sheet-metal strip at the end of the second limb. According to one illustrative embodiment of this configuration of the invention, the first side wall can additionally be arranged on the shielding side wall, e.g. by angling the shielding side wall in the direction of the angle edge in the inlet region of the recess. However, this illustrative embodiment can also be implemented, for example, by means of an angled plate having a first and a second limb, on which a tubular piece, the rectangular cross section of which extends perpendicularly to the angle edge, is arranged.
Provision can furthermore advantageously be made for the reinforcing device to be implemented at least partially by means of profiling of the second limb.
Here, profiling of the second limb should be taken to mean shaping of the limb which deviates from the substantially planar extent of the limb, such as an undulating profile of the limb material or a quadrilateral fixed on the limb.
The second limb can advantageously have an undulating profile at least partially parallel to the angle edge.
The undulating profile allows reinforcement of the angled plate. The reinforcing device can be implemented exclusively by means of the undulating profile of the second limb, for example. Here, the undulating profile can be designed in such a way that at least one undulation comprises a lateral surface, which at least partially reflects cooling air flowing laterally out of the bolt head. In addition to the mechanical reinforcement of the angled plate brought about by means of the undulating profiling, this produces a cooling effect on the angled plate and hence a further increase in the dimensional stability of the component. The advantageous configuration of the invention can be produced from a standard component, upon which an undulating profile is imposed. This reduces production costs.
Provision can furthermore advantageously be made for the second limb to have an undulating profile at least partially perpendicularly to the angle edge.
This likewise allows implementation of the invention with reduced production costs. The undulating profile can extend over the entire width of the second limb, for example. Thus, the profiling extends partially behind the penetration region, as seen from the angle edge, and reinforces this region.
Provision can furthermore advantageously be made for the undulating profile to be sinusoidal, wherein the undulating profile traverses the sine function substantially from 0 to 2π.
The formation of one undulation peak and one undulation trough is already sufficient to allow adequate reinforcement of the angled plate. This simplifies the production of the angled plate.
Another advantageous configuration of the invention can provide for two such recesses to be arranged on each of two opposite circumferential sides of the heat shield block, thus allowing the heat shield block to be secured to the support structure by means of four securing bolts arranged in opposite pairs.
This securing option allows particularly stable arrangement of the heat shield block on the support structure.
It can also be regarded as advantageous that the securing bolt is secured releasably to the support structure by means of a diaphragm spring assembly arranged on the support structure.
Provision can furthermore advantageously be made for a hole in alignment with the securing bolt to extend through the heat shield block from the hot side to the recess.
This allows simple access to the bolt head for an assembly tool.
It can also be regarded as advantageous that the reinforcing device of the angled plate comprises, in the penetration region, a reinforcing body which is arranged between the first and the second limb, projects into the aperture and is arranged by means of a lateral surface on the first limb and by means of an upper side on the second limb, wherein the reinforcing body has a through bore for the securing bolt, with the result that the securing bolt passes by means of a shank of the securing bolt through the penetration region and the reinforcing body.
The securing bolt can thus be inserted by means of its bolt shank into the angled plate through the penetration region of the second limb and the reinforcing body, with the result that the bolt head rests on the second limb and the shank projects through the second limb and through the reinforcing body. The angled plate is positioned on the circumferential surface of the heat shield block together with the bolt, with the second limb and the bolt head in the recess, and the reinforcing body and the bolt shank extending through the reinforcing body in the aperture.
Provision can advantageously be made for the reinforcing body to have a substantially semicircular upper side parallel to the second limb, wherein the straight side of the semicircle rests on the first limb.
The reinforcing body can thus have a semicircular cross section parallel to the second limb.
As an alternative, provision can be made for the upper side of the reinforcing body resting on the second limb to have substantially the shape of a triangle with a rounded apex, wherein the apex is rounded substantially to match the through bore, and the base of the triangle adjoins the first limb.
The reinforcing body can have a cross section corresponding to the triangular upper side over its entire height (perpendicularly to the second limb).
However, the height of the reinforcing body can be less at the apex than at the base, with the result that the shape of the reinforcing body corresponds substantially to that of a right prism with the rounded triangular shape as the base surface, wherein the side opposite the upper side is not arranged parallel to the upper side. The prism is thus of beveled design opposite the upper side. As a result, the side regions of the reinforcing body which extend perpendicularly to the second limb act as reinforcing ribs.
It can also be regarded as advantageous if the angled plate is designed as an integral casting with the reinforcing device.
In particular, it is thus possible to produce the angled plate together with the reinforcing body as an integral casting.
The material of the casting can be Nimonic 90, for example.
A number of such angled plates with a reinforcing device can be produced simultaneously by means of casting methods, especially “sprue molding”. This reduces production costs.
It is another object of the invention to specify a combustion chamber lined with the heat shield mentioned at the outset, and a gas turbine having a combustion chamber of this kind, which allows securing of a heat shield block and avoids detachment of the heat shield block from the support structure in a particularly reliable manner.
According to the invention, this object is achieved, in the case of a combustion chamber of the type stated at the outset, by virtue of the fact that the heat shield is designed as respectively claimed.
This object is achieved, in the case of a gas turbine of the type stated at the outset, by virtue of the fact that at least one combustion chamber is designed as respectively claimed.
Further expedient configurations and advantages of the invention form the subject matter of the description of illustrative embodiments of the invention with reference to the figure of the drawing, wherein the same reference signs refer to components having the same effect.
In the drawing:
During the operation of the gas turbine 1, air 23 is drawn in through an air inlet 21 of the compressor section 3 and is compressed by the compressor rotor blades 11. The compressed air is fed to a combustion chamber 25, which is arranged in the combustion chamber section 5 and, in the illustrative embodiment under consideration, it is configured as an annular combustion chamber lined with a heat shield 2, into which a gaseous or liquid fuel is also sprayed via at least one burner 27. The air/fuel mixture thereby formed is ignited and burned in the combustion chamber 25. The hot combustion exhaust gases flow along the flow path 29 from the combustion chamber 25 into the turbine section 7, where they expand and cool and, in the process, transfer momentum to the turbine rotor blades 13. During this process, the turbine guide vanes 17 serve as nozzles for optimization of momentum transfer to the rotor blades 13. The rotation of the shaft 9 brought about by the momentum transfer is used to drive a load, e.g. an electric generator. Finally, the expanded and cooled combustion gases are discharged from the gas turbine 1 through an outlet 31.
The securing bolt 56 is internally cooled. For this purpose, the securing bolt according to the illustrative embodiment shown has a cooling air duct 64, which extends parallel to a longitudinal axis 66 of the securing bolt in the shank of the securing bolt 56. The cooling air duct 64 shown opens into four cooling air openings 68, which are arranged on the side of the bolt head 70. Cooling air flowing out of these cooling air openings 68 is illustrated by means of arrows 72. The second limb 58b has a reinforcing device 74, which increases the bending stiffness of the angled plate 58. In the illustrative embodiment shown, the reinforcing device 74 is formed by means of an undulating profile of region 58b. For this purpose, the reinforcing device 74 extends longitudinally over the entire width 78 of the angled plate, parallel to the angle edge 60. The second limb thus includes profiling, which extends at least partially behind the penetration region, as seen from the angle edge, and reinforces this region, with the result that a resistance of the angled plate to bending caused by the securing bolt is increased. The reinforcing device 74 also has a surface 80 which partially reflects cooling air 72 flowing out at the side of the bolt head 70. A penetration region penetrated by the securing bolt 56 is denoted by the reference sign 82.
In its interior, the securing bolt 56 comprises a cooling air duct 64, which opens into outlet openings arranged laterally on the bolt head 70. The cooling air flowing out at the side of the bolt head 70 is held in the recess 34 owing to the first side wall 98a and flows out with a time delay, e.g. through the assembly opening 102. The reinforcing device 98 leads to significantly improved cooling of the angled plate 96, with the result that dimensional stability of the angled plate 96 comprising the reinforcing device 98 is increased. The angled plate 96 comprising the reinforcing device 98 has increased resistance to a force in the direction of the support structure 28 exerted on the angled plate by the securing bolt 56.
The shielding side wall 114 shields the second limb 110b from the entry of hot gas. Owing to the reduced ambient temperature, this increases dimensional stability of the angled plate 110. Owing to its shape, the angled plate 110 furthermore has increased resistance of the angled plate 110 to bending caused by the securing bolt 56. In addition, a cooling air space 116, which is delimited by the angled side wall 112 and the shielding side wall 114 and into which cooling air emerging at the side of the bolt head 70 of the securing bolt 56 is directed back onto the angled plate 110, thus increasing the dwell time of the cooling air in the recess 34, is achieved.
Perpendicularly to the second limb 140b, at the apex of the triangular upper side 150, the reinforcing body 142 has a smaller height than at the base, with the result that the reinforcing body 142 has substantially the shape of a prism with the upper side 150 as a base surface, wherein the prism is beveled opposite the upper side.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102013212509.7 | Jun 2013 | DE | national |
This application is the US National Stage of International Application No. PCT/EP2014/063705 filed Jun. 27, 2014, and claims the benefit thereof. The International Application claims the benefit of German Application No. DE 102013212509.7 filed Jun. 27, 2013. All of the applications are incorporated by reference herein in their entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2014/063705 | 6/27/2014 | WO | 00 |
