Compensation assembly for a damper of a gas turbine

Abstract

The present invention relates to dampers for gas turbines and, for example, to a compensation assembly for a damper of a gas turbine for reducing the pulsations occurring in the combustion chamber. The damper can include a resonator cavity with a neck tube in flow communication with the interior of the combustion chamber, wherein the compensation assembly includes a spherical joint associated to the neck tube and configured to allow relative rotation between the combustion chamber and the resonator cavity, and having a bulb portion disposed around the neck tube and a spherical socket configured to internally host the bulb portion, wherein the spherical socket can have a top collar portion and a bottom collar portion connected to each other.

Claims

1. A compensation assembly for a damper of a combustion chamber of a gas turbine, the damper having a resonator cavity with a neck tube in flow communication with an interior of the combustion chamber, the compensation assembly comprising: a spherical joint associated to a neck tube and configured to allow relative rotation between a combustion chamber and a resonator cavity, the spherical joint including: a bulb portion configured as a collar element for disposal around the neck tube; a spherical socket configured to internally host said bulb portion, wherein the spherical socket has a top collar portion and a bottom collar portion, the top and bottom collar portions being connected to each other by a joint; and a sliding part formed directly on the spherical socket and configured to be air-tightly fitted into a groove of the resonator cavity in a direction traversing a longitudinal axis of the neck tube between said sliding part and the groove, wherein said collar element is internally shaped for relative radial displacement of the neck tube along the longitudinal axis of the neck tube.

2. The compensation assembly according to claim 1, in combination with a damper having the resonator cavity with the neck tube, wherein said bulb portion is inserted on the neck tube.

3. The compensation assembly according to claim 2, wherein said collar element defines internally a cylindrical surface.

4. The compensation assembly according to claim 1, wherein said bottom and top collar portions are connected by complementary threaded portions as the joint.

5. The compensation assembly according to claim 1, wherein said sliding part is formed directly on said top collar portion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The objects, advantages and other features of the present invention will become more apparent upon reading of the following non-restrictive description of preferred embodiments thereof, given for the purpose of exemplification only, with reference to the accompany drawing, through which similar reference numerals may be used to refer to similar elements, and in which:

(2) FIG. 1 shows a schematic sectional view of a compensation assembly according to the present invention;

(3) FIG. 2 shows a comparison of exploded views of a compensation assembly according to the prior art (left) and the compensation assembly according to the present invention (right);

(4) FIG. 3 shows a cross-sectional view of the compensation assembly according to the present invention;

(5) FIGS. 4 and 5 show a comparison between the mounting of the compensation assembly according to the prior art (left) and the mounting of the compensation assembly according to the present invention (right) on the neck tube;

(6) FIG. 6 shows an annular portion of a carrier structure of a combustion chamber;

(7) FIG. 7 shows a perspective view of a segment where a neck tube is mounted;

(8) FIG. 8 shows a perspective view of an insert element according to the present invention; and

(9) FIGS. 9 and 10 show subsequent section/frontal views of the segment where the neck tube and the insert element are mounted.

DETAILED DESCRIPTION OF THE INVENTION

(10) With reference to FIG. 1, it is shown a schematic cross sectional view of a compensation assembly according the present invention, generally denoted with numeral reference 1. The compensation assembly 1 is associated to a damper of a combustion chamber 3. The damper comprises a resonator cavity 4 with a box or cylinder shape as delimitated by a peripheral wall 13 and an inlet 14. As shown in FIG. 1, the major part of the resonator cavity 4 is cut away as this would not prevent full and complete understanding of the technical solutions of the present invention. Also, only parts of the combustion chamber 3 closely related to the present invention is shown in FIG. 1 for clarity and simplicity. The resonator cavity 4 is air tightly attached to a carrier structure 11 of a combustion chamber 3 by fasteners, not shown in FIG. 1. In an example implementation of the present invention, the carrier structure 11 of the combustion chamber 3 may be a casing of the combustion chamber 3. Those skilled in the art should appreciate that the carrier structure 11 provides a carrier for the resonator cavity 4, and should not be limited to the casing of the combustion chamber as described herein. In addition, the damper comprises a neck tube 5 that is in flow communication with the resonator cavity 4 through the compensation assembly 1 according to the present invention in order to compensate relative movement between the resonator cavity 4 and the combustion chamber 3.

(11) The neck tube 5 is air tightly attached at a first end 91 thereof to a wall portion 9, or segment, of the combustion chamber 3. For example, a first end 51 of the neck tube 4 may be welded to the segment 9 of the combustion chamber 3. The compensation assembly 1 comprises a spherical joint, generally denoted with 6, associated to the neck tube 5 and configured to allow a relative rotation between the combustion chamber 3 and the resonator cavity 4. In particular, the spherical joint 6 comprises a bulb portion 61 which is disposed around the neck tube 5 and a spherical socket 62 which, in turn, is internally adapted to host the bulb portion 61 such to permit relative rotation between resonator cavity 4 and combustion chamber 3. More in particular, spherical socket 62 is formed by a top collar portion 621 and a bottom collar portion 622 connected to each other.

(12) According to a preferred embodiment of the invention, the bulb portion 61 is also a collar element 61 which is inserted on the neck tube 5 and comprises an external rounded portion which is movable within the spherical socket 62.

(13) Advantageously, the collar element 61 is internally shaped such to permit a relative radial displacement as indicated by arrow R in the drawing. Preferably, the collar element 61 internally defines a cylindrical surface, where the neck tube 5 is accommodated and can slide radially to compensate in such direction possible radial thermal expansions. Furthermore, in order to provide the resonator cavity 4 with means adapted to compensate possible thermal axial expansions along a direction traversing a longitudinal axis of the neck tube 5, indicated in the figure by arrows A, compensation assembly 1 comprises a sliding part 7 formed on the spherical socket 62 and adapted to be air-tightly fitted within a groove 8 of the resonator cavity 4. Preferably, sliding part 7 is formed on the top collar portion 621 of the spherical socket 62.

(14) With reference to next FIG. 2, it is showed a comparison between exploded views of a compensation assembly according to the prior art (left) vs the compensation assembly according to the present invention (right).

(15) The compensation assembly according to the prior art comprises two half-collar portions 102 and 103 which are connected along the longitudinal direction of a neck tube 104. A bulb portion is integrally formed on the neck tube 104, which is hosted into a correspondent internal spherical socket formed by the half-collar portions 102 and 103 after their connection, which is effected by a third top junction element 100 and an annular portion 101. Differently and advantageously, the compensation assembly according to the invention involves a reduction of number of parts to be assembled as well as the avoidance of a bulb portion integrally formed on a portion of the external surface of the neck tube 104. In fact, the bulb portion 61 is now enclosed within the two collar portions 621 and 622 connected along a direction which is transversal with respect to the longitudinal axis of the neck tube. Preferably, the two top and bottom collars 621 and 622 are connected by means of complementary threaded portions. Additionally, the bulb portion 61 is yet a collar element internally cylindrically shaped such to accommodate the neck tube (not pictured) and allow relative radial displacement. Differently, according to the prior art, the annular portion 101 is also hosted into a yet another external collar (not shown) to provide radial displacement. Such external collar comprises sliding parts. According to the invention, the sliding parts 7 are advantageously formed on the top collar portion 621 of the spherical socket 62.

(16) Making now reference to following FIG. 3, it is shown a cross sectional view of the compensation assembly according to the present invention. In particular, it is clearly shown the bulb portion of the collar element 61 which is hosted into a correspondent spherical socket formed by the connection of the top and bottom collar portions 621 and 622 by means of a thread.

(17) FIGS. 4 and 5 show the insertion of the compensation assembly into the neck tube according to the prior art (left) and according to the present invention (right). According to the known art, the neck tube presents an external bulb-shaped portion 104 which is adjusted inside a spherical socket formed by connection of half-collar elements 102 and 103 which are secured via the third top junction element 100 and the annular portion 101. To provide radial displacement, the assembly thus formed is yet lodged into the now visible external collar 105, provided with sliding parts for enabling radial displacement. The compensation assembly according to the present invention, conversely, is provided by the connection of a less number of components, that is the collar element 61 disposed around the neck tube 5 providing radial displacement and the spherical socket formed by connection of top and bottom collar elements 621 and 622. The spherical socket provides also means for compensating axial displacement, as sliding part 7 is formed directly on the top collar portion 621.

(18) It will then be appreciated that the new compensation assembly, compared to the known art, facilitates the assembly procedure in the factory, improves the sourcing of the different parts as well as facilitating the machining of the different components. As the number of components is reduced, this advantageously affects the costs involved. Furthermore, the assembly according to the prior art needed to be assembled to the segment prior to the installation in the gas turbine. The innovative design can be assembled independent from the segment. It may be installed during the assembly of the gas turbine.

(19) It will also be appreciated that separating the assembly of the segment and the spherical joint improves the sourcing. The assembly according to the invention may be ordered at a different supplier and directly delivered to the gas turbine assembly site. The spherical joint of the assembly according to the invention may be manufactured by turning operation, whilst the assembly according to the prior art requires turning operations as well as EDM (Electric Discharge Machining). In particular, EDM is generally used for the half collar elements 102 and 103 which is an expensive cutting operation. Separating the assembly of the segment and the spherical joint also allows the sourcing of both parts at the most cost-effective place. By reducing the manufacturing steps costs can be saved.

(20) FIG. 6 shows the carrier structure 11 in a perspective view. In order to enable the installation of the segment with the protruding neck into the carrier structure 11 it is advisable to have a sufficient wide opening. For this reason, an elongated opening 111 is advantageously provided in the carrier structure 11, where the neck tube is inserted (not shown). In order to close an open gap formed between the opening 111 in the carrier 11 and the neck tube, an insert element (not shown in the figure) is introduced and connected to the carrier structure 11 at the interface between the protruding neck tube (not shown) and the carrier structure 11, in correspondence of the elongated opening 111.

(21) Next FIG. 7 shows a perspective view of the segment 9, having cooling channels 91 formed on its surface, on which the protruding neck tube 5 of the resonator cavity is attached. As clearly visible in the figure, by implementing a neck tube into the segment 9, the cross section area of the cooling channels adjacent thereto reduces significantly. This leads to a reduction of cooling air flow, which results in an increased temperature of the component. It has been proven that it is not sufficient to increase the cross section area of the cooling channels by removing the ribs. There are not enough ribs to compensate for the neck blockage and also the ribs are necessarily required for the mechanical integrity of the segment. Advantageously, the insert element is introduced between the neck tube 5 and the elongated hole located on the carrier structure to address such technical problem.

(22) The insert element is shown in a perspective view in following FIG. 8, and generally denoted with the numeral reference 12. In particular, the insert element 12 comprises a connecting portion 121 adapted to secure the insert element 12 to the carrier structure (not shown), a through hole 122 for admitting the neck tube and a base slopped portion 123. Advantageously, the base slopped portion 123 is such to increase the height of the cooling channel, in order to compensate for the blockage due to the presence of the neck tube, thus providing a wider channel for the cooling fluid. More in particular, the insert is positioned in such a way that it facilitates the increase of the cooling channel height. The increase of the cooling channel height is aerodynamically formed to avoid unnecessary pressure losses therein.

(23) This is better explained and illustrated with reference to last FIGS. 9 and 10, taken in combination. FIG. 9 shows the schematic sectional view of the neck tube 5 protruding from the segment 9 through the elongated opening 111, wherein the opening 111 is closed by the insert element 12, comprising the connecting portion 121 securing the insert 12 to the carrier structure 11 and the slopped portion 123. In the drawings subsequent section lines A-F are indicated, and correspondent frontal views of the segment 9 are depicted in FIG. 10. It is in fact shown how, advancing along the cooling channels 91 of the segment 9, the slopped portion 123 provides a compensation for the reduction of the cooling channels 91 due to the presence of neck tube 5. In fact, in correspondence of sections C-F the slopped portion 123, decreasing the extent of its section, increases the height of the channels 91 providing such compensation.

(24) While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.