EP2273196A2 - Gas turbine combustion chamber head - Google Patents

Abstract

The combustion-chamber head has a boundary compassing a damping volume, a combustion chamber turned off boundary (206) and a combustion chamber siding boundary (210). The combustion chamber side boundary is formed in the form of a perforating wall. Cool air on the combustion chamber side boundary is conveyed into the border by recesses (203) in the edge region of the combustion chamber side boundary. The cool air flows along the combustion chamber side boundary. The cool air flow crosses in the combustion chamber through the perforating wall.

Description

The invention relates to a combustion chamber head of a gas turbine and more particularly to a combustion chamber head having the features of the preamble of claim 1.

The structure of a conventional heat shield for the combustion chamber head is in the DE 44 27 222 A explained. This protects the combustion chamber head from hot gases and must be cooled on the side facing away from the combustion chamber interior. In this case, cooling air reaches the rear of the heat shield, bounces here and flows around a plurality of cylinders, which are used to enhance the heat transfer. The cooling air then leaves the gap between the heat shield and the burner head via employed effusion bores which point in the direction of the burner swirl.

It is also known a combustion chamber head, which consists of a end wall, a front panel and a heat shield. This is a three walled construction of a combustor head with an open volume between the end and front panels. The function of the end wall is to guide the flow of air coming from the compressor.

The principle of a surge-cooled combustion chamber wall element is in the WO 92/16798 A shown. Cooling air flows through orthogonal holes in an outer wall and bounces on an inner wall. Both walls form a closed volume, which leaves the cooling air over employed Effusionsbohrungen. In this case, a cooling film is formed on the hot side of the inner wall, which protects the wall from the hot combustion gases.

In other publications, such as the EP 0 971 172 A , the principle of the impact-cooled combustion chamber wall has been extended by the aspect of damping of combustion chamber vibrations. Here, the effusion wells, together with the volume enclosed by the walls containing the impact and effusion bores, form a plurality of interconnected Helmholtz resonators. So can high-frequency oscillations in the range around 5kHz be steamed. The distance between the damping holes and the distance between the walls are made variable in order to produce a broad attenuation spectrum.

Eldredge and Dowling have in their 2003 release " 485, pp. 307-335, Cambridge University Press ) provides a model for describing the broadband acoustic attenuation effect of perforated wall elements. From this it follows that the absorption of acoustic vibrations by perforated wall elements in a single-walled construction under plenum flow is large and broadband acts. If a second wall is introduced, as in the impact effusion setup, the absorption is significantly influenced by the wall containing impingement cooling holes. The influence can be reduced with increasing distance and thus approximated to the damping effect of a single-walled damper. Plenum flow in this context means that there are no significant pressure or velocity fluctuations in this volume (it does not resonate!), In contrast to a Helmholtz resonator. Also, because of the broadband nature of the effect, the volume need not be tuned to the frequency to be damped, as in a Helmholtz resonator. Also, the volume used in the damper is significantly smaller than calculated from the equation known for resonator volume and frequency.

One way to provide an increased damping volume is in the EP 0 576 717 A shown. Here, an additional volume is connected to a double-walled element, which serves to form a Helmholtz resonator volume. The resonator volume is dimensioned according to the occurring wavelengths.

The CA 26 27 627 A shows a heat shield with ribs on the side facing away from the combustion chamber. The ribs are connected together at one end and have with their open side to the inner and outer combustion chamber wall. It bounces cooling air between the ribs and is guided by means of the ribs to the combustion chamber walls. This is to prevent the impact cooling jets from influencing each other too strongly. The effects of the incoming cross flow should be avoided.

In the US 2007/0169992 A the problem of the agreement of a large wall distance of the baffle and effusion wall to ensure a large damper volume, with simultaneous high impact cooling effect has been recognized. The solution proposes to bridge the distance between the two wall elements by conduits directed from the outer cold combustion chamber wall to the hot combustion chamber wall so as to allow an optimum impingement cooling clearance while maintaining a large damper volume.

Conventional heat shields, such as the DE 44 27 222 A , have a small distance from the top plate to the heat shield. This is necessary to achieve a sufficient impact cooling effect ( WO 92/16798 ). However, if one wants to exploit the viscous damping effect of a perforated perforated plate, a large volume of damping behind the heat shield is necessary (Eldredge and Dowling 2003). Otherwise, only high-frequency components of the combustion chamber oscillations can be generated by applying the principle of coupled Helmhotz resonators ( EP 0 971 172 A ) are dampened. If an additional volume is connected to a double-walled element ( EP 0 576 717 A ) so this volume to trim to an expected frequency, which is the advantage of a perforated wall element as a damper opposite. Since both wall elements continue to be close to each other, the negative influence of the outer impact cooling wall can not be excluded.

Although the employed effusion wells shown in the publications mentioned above have a high film cooling efficiency. However, a poorer damping effect is achieved than with vertical holes. It can therefore be said that the requirements of the damping and cooling effect are in conflict.

The Indian DE 44 27 222 A illustrated combustion chamber head with the additional flow-leading end plate has the disadvantage that the volume between the end and front plate is not decoupled from the burner, closed volume. It may thus be the case that pressure fluctuations in this volume affect the stability of the burner. The end plate is thus intended only as a flow-conducting element.

The construction according to US 2007/0169992 A Although allows a high impact cooling effect while maintaining a large damper volume. However, due to the necessity of connecting each impingement cooling hole to a pipe, this construction is very expensive and, in fact, impractical for installation in the combustion chamber with several thousand impingement cooling holes. Furthermore, lost volume through the long pipe, so that this method is ineffective.

The invention has for its object to provide a combustion chamber head of the type mentioned, which meets the thermal requirements with a simple structure and simple, cost-effective manufacturability and ensures a high degree of damping.

According to the invention the object is achieved by the combination of features of claim 1, the dependent claims show further advantageous embodiments of the invention.

According to the invention it is thus provided that the combustion chamber head forms a volume which is delimited by a wall relative to the combustion chamber, wherein on the flammenabgewandten side of this boundary of the air flow for cooling the boundary and the air flow through the wall for damping the vibrations without possibility of mixing cross.

According to the invention thus results in a highly effective acoustic damping, combined with an excellent thermal shielding of the structure against the heat in the combustion chamber.

Abb. 1

eine schematische Darstellung einer erfindungsgemäßen Gasturbine mit Brennkammerkopf gemäß dem Stand der Technik,

Abb. 2

eine vergrößerte Detailansicht einer erfindungsgemäßen Ausgestaltung des Brennkammerkopfes,

Abb. 3a-3e

Detailansichten der Oberflächengestaltung des Hitzeschildes,

Abb. 4a-4d

perspektivische Darstellungen von Wärmeübergangselementen, analog den Abb. 3a-3e, und

Abb. 5a-5c

weitere Ausführungsbeispiele des Übergangs zwischen Brennkammerwand und Hitzeschild.

In the following the invention will be described by means of embodiments in conjunction with the drawing. Showing:

Fig. 1

a schematic representation of a gas turbine according to the invention with combustion chamber head according to the prior art,

Fig. 2

an enlarged detail view of an embodiment of the combustion chamber head according to the invention,

Fig. 3a-3e

Detailed views of the surface design of the heat shield,

Fig. 4a-4d

perspective views of heat transfer elements, analogous to Fig. 3a-3e , and

Fig. 5a-5c

Further embodiments of the transition between the combustion chamber wall and heat shield.

First, the combustion chamber head according to the invention in conjunction with a schematic representation of a gas turbine in connection with Fig. 1 described.

The combustion chamber head consists of a perforated wall 210 facing the hot gas and a boundary 206 terminating the volume 207. A closed volume 207 is formed. The perforated wall 210 has ribs 201. Holes 202 in the wall 210 preferably extend through the ribs 201.

The necessary for the flow through the combustion chamber head air passes through lateral access 203 into the combustion chamber 112. In this case, a beam is generated, which strikes the wall 210 at an angle β of 0-80 °.

The result is a flow channel between two ribs, in which a flow of increased speed is formed (see Figure 4a ). This absorbs heat through the ribs and thus leads to cooling of the component.

Depending on the hole diameter of the inlet hole 203 and the local pressure level, the air jet will lift off the wall 210 after a characteristic run length and enter the volume 207.

According to the invention, the flow channel 218, which is formed by ribs or heat transfer elements (see FIGS. 4a and 4b), can be supplemented by a cover 219, resulting in a partially closed flow channel. As a result, the air jet is guided near the wall 210 and adjacent to the ribs 201.

According to the invention it is also possible to increase the heat transfer at the combustion chamber side boundary to arrange additional heat transfer enhancing elements 220 in the flow channel 218 or on the ribs 201, see for example Figure 4c ,

The flow thus initially runs parallel to the wall 210, lifts off from the wall 210 (combustion chamber side boundary) and enters the volume 207 from where it leaves the combustion chamber head through the holes 202 in the wall. The incoming and outgoing air mass flows cross in their direction of movement, but are separated by walls and therefore do not mix. There is a clear separation of the cooling and damping function by the different direction of movement and flow control of the air jet in the combustion chamber head.

The volume 207 is preferably dimensioned so that a plenumnahe flow is ensured for the outlet holes 202. This occurs in the event that the flow of the outlet holes 202 is no longer affected by the supply air. It can be a distance of a minimum of 2mm to a maximum of the length of the burner 102 can be selected. In order to achieve a broadband damping effect, the size of the damping volume, unlike Helmholtz resonators regardless of expected resonance frequencies selected. The volume required for a Helmhotzresonator is calculated according to $$V={\left(\frac{a_0}{2\mathit{<figure-callout\; id="2"\; label="\pi f"\; filenames="imgf0002.png"\; state="\{\{state\}\}">\pi f</figure-callout>}}\right)}^2\frac{S_0\sigma }{l_{\mathit{eff}}}$$

Where a _{0 is} the speed of sound, f is the resonant frequency, So is the cross-sectional area of the resonator neck and l _{eff is} the resonator neck length. It is frequency-dependent and significantly larger than the volume 207 required here.

The volume 207 can be designed as a circumferentially continuous volume. The volume 207 can be segmented by additional partitions into individual mutually closed volumes. In the case of a segmented volume 207, the volumes may be the same size or different sizes.

The height of the ribs 201 is preferably chosen so that the lifting of the air jet from the inlet bores 203 as far as possible downstream of the Zuluftlöcher 203 takes place in order to allow the highest possible cooling effect along the entire wall 210. In particular, heights of 1mm - 10mm are considered advantageous.

Alternatively, individual or groups of exit holes 202 may pass through individual rib members 227 and 228. The rib elements can be arranged arbitrarily. The cross section of the rib elements can be arbitrarily shaped. The function is not affected by this. Illustrated in FIG 3d illustration and 4d an aerodynamic profile and in Figure 3e and 4e a circular profile. Rectangular, diamond-shaped, hexagonal, elliptical, prismatic profiles are also conceivable. Also, a combination of the above profiles can be used, as well as profiles formed by the intersection of circle segments.

The ports (entrance passage 203) may also be selectively placed near the combustor 102 via the inner sidewall of the combustor head 213, and then flow along the ribs toward the outer sidewall of the combustor head 112.

The construction can be integrally combined as an integral component, or several pieces of several components, with a sufficient seal is to pay attention. The combustion chamber head is attached to the combustion chamber wall, preferably via in each case at least one fastening element.

The effective area of the exit holes 202 is preferably larger than that of the supply holes 203 by a factor of 2-10.

By adjusting a gap 214 between the combustion chamber wall 204 and the outer side wall at the level of the inlet hole 203 (see Figure 2 and Figure 3a ), an initial cooling film may be placed on the combustion chamber wall 204. Alternatively, an effusion hole 217 set in the direction of the combustion chamber wall can be integrated in the wall 210 (eg Figure 3b and 5a ) which replaces the function of a first cooling film. In this case, the outer side wall of the combustion head plate lies on the outer combustion chamber wall. The effusion hole can optionally through the wall 210 or the rib 201 lead. Another option is to drill additional holes 215 (see Figure 3c ) in the combustion chamber wall 204. These then do not point into the inlet holes of the combustion chamber head, but into a groove 216 which lies in the side wall 204. The groove is continuous in the side wall in the direction of the wall 210. The air flows through the bore 215, bounces on the side wall 212 and passes through the groove 216 in the combustion chamber (see Figure 5b ).

In order to ensure a sufficient flow to the burner, the wall 213b can be made at an angle α relative to the burner axis 208. It may also optionally be a fillet in place or in addition to the angle.

The combustion chamber wall 204 can alternatively also be designed as a two-walled construction, comprising an inner wall 221 facing the hot gas and a side 226 facing the cold outer flow. The outer and inner combustion chamber walls can optionally be perforated (see reference numerals 222 and 223 in FIG Figure 5c ). The volume 225 formed between the outer and inner combustion chamber walls may be connected to the volume 207 through a flow passage 224.

The structure described here makes it possible to integrate an effectively highly acoustically damping, sufficiently cooled damper element in the top plate of a combustion chamber. Usually, dampers optimized for low frequencies require a large volume of construction. The structure used here makes it possible to effectively use the given space in a combustion chamber to allow a broadband attenuation, especially in the low-frequency range (frequencies below 2000Hz). For this purpose, the broadband damping effect of perforated walls, which usually turns out to be low, with that of a Helmholtz resonator whose effect is large, connected. The skillful utilization of the volume lying between the burner heads to approach a plenum-like flow for the damping holes, a particularly high damping effect can be achieved. As a result, the already high damping effect of a Helmholtz resonator can be far exceeded.

While conventional double-walled configurations require a small distance between the two walls in order to allow a sufficient cooling effect, the structure according to the invention requires only a convective cooling concept for the thermally loaded wall.

The solution according to the invention thus combines the oppositely behaving claims of cooling and damping design with simple and practical for use funds. It is possible in a double-walled construction to integrate a large volume and still achieve a high cooling effect through a changed inflow into the volume.

LIST OF REFERENCE NUMBERS

101

combustion chamber

102

Burner with arm and head

103

sidestream

104

fan

105

compressor

106

Verdichterleitrad

107

Inner combustion chamber housing

108

Outer combustion chamber housing

109

turbine nozzle

110

turbine impeller

111

drive shaft

112

bulkhead

201

Rib / dividing wall

202

Outlet hole / recess / bore

203

Entry hole / recess / bore

204

combustion chamber wall

205

fastener

206

Combustion chamber facing edge (wall)

207

Combustor head volume / damping volume

208

Brenner

209

sealing element

210

Combustion chamber side boundary (wall)

211

Combustion chamber wall cooling holes

212

Outer side wall of the combustion chamber head

213

Inner side wall of the combustion chamber head

213b

Front part of the inner side wall of the combustion chamber head

214

gap

215

Supply air hole for initial cooling film

216

Groove for continuing the initial cooling film

217

effusion

218

flow channel

219

Cover of the flow channel

220

Heat transfer enhancing element

221

Inner combustion chamber wall

222

Bore in the inner combustion chamber wall

223

Bore in the outer combustion chamber wall

224

connecting pipe

225

Volume between outer and inner combustion chamber wall

226

outer combustion chamber wall

227

Fin member; aerodynamic profile

228

Rib element, circle profile

Claims (15)

Combustion chamber head of a gas turbine with a boundary enclosing a damping volume (207), consisting of a boundary remote from the combustion chamber (206) and a combustion chamber side boundary (210), characterized in that the combustion chamber side boundary (210) is in the form of a perforated wall (210), that cooling air can be conducted to the combustion chamber side boundary (210) by recesses (203) in the boundary (206) in the edge region of the combustion chamber side boundary (210), that cooling air flowing along the combustion chamber side boundary (210) directs the cooling air flow through the perforated one Wall (210) in the combustion chamber (101) crosses, is separated from this by walls and does not mix with her. Combustor head according to claim 1, characterized in that the combustion chamber side boundary (210) for guiding the cooling air over the combustion chamber (201) side facing away from the combustion chamber side boundary (210), subsequently for deflecting the cooling air into the volume (207) and subsequently to the outlet the cooling air is formed by recesses (202) in the combustion chamber (101). Combustor head according to claim 1 or 2, characterized in that the combustion chamber side boundary (210) on the side facing away from the combustion chamber (101) is provided with the heat transfer surface enlarging elements. Combustor head according to claim 2 or 3, characterized in that the recesses (202) pass through the heat transfer surface enlarging elements. Combustor head according to claim 3 or 4, characterized in that the heat transfer surface enlarging elements in the form of ribs (201) and / or in the form of cuboidal or profiled webs and / or in the form of cylindrical or profiled pins are formed. Combustor head according to one of claims 2-5, characterized in that the recesses (202) lead through the heat transfer surface enlarging elements substantially parallel to the axis of symmetry of the head of the burner (102) through the surface of the combustion chamber side boundary (210). Combustor head according to one of claims 2-5, characterized in that the recesses (202) through the heat transfer surface enlarging elements substantially normal to the local surface on the combustion chamber side facing the combustion chamber side boundary (210) at the location of the air outlet from the recesses ( 202) into the combustion chamber. A combustor head according to any of claims 2-5, characterized in that the recesses (202) pass through the heat transfer surface enlarging elements at an angle of 10-90 degrees to the local surface on the combustion chamber side of the combustion chamber side boundary (210) at the location of the air exit from the recesses (202) lead into the combustion chamber. Combustor head according to one of Claims 1 to 8, characterized in that the flow direction of the cooling air flowing through the inflow recess (203) is inclined at an angle (β) to the plane of the combustion chamber side boundary (210). Combustor head according to one of claims 1 to 9, characterized in that the Einströmausnehmung (203) on the inner side wall (213) of the combustion chamber head (112), the cooling air from the burner radially outwardly toward the outer side wall of the combustion chamber head (112) passes. Combustor head according to one of claims 1 to 10, characterized in that a partially closed flow channel (218) for the cooling air is formed by a cover (219). Combustor head according to claim 11, characterized in that the closed flow channel (218) of the cooling air has additional flow obstacles (220). Combustor head according to one of claims 1 to 12, characterized in that the combustion chamber head (112) comprises additional dividing walls in the circumferential direction for segmenting the volume (207) into individual sealed volumes separated from each other. Combustor head according to one of claims 1 to 13, characterized in that the size of the exit surface of the recesses (202) by a factor of 2-10 is greater than the cross-sectional area of the recesses (203). Combustor head according to one of claims 1 to 14, characterized in that in the combustion chamber wall (204) additional recesses (215) are formed, which in a groove in the outer side wall (212) of the burner head (212) facing the combustion chamber (101 ) and / or that the damper volume (207) is connected by a flow channel to the cavity (225) formed by an outer (226) and an inner (221) combustion chamber wall.

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