EP3392468B1

EP3392468B1 - Exhaust diffuser of a gas turbine engine having variable guide vane rings

Info

Publication number: EP3392468B1
Application number: EP17193245.2A
Authority: EP
Inventors: Dae Hyun Kim
Original assignee: Doosan Heavy Industries and Construction Co Ltd
Current assignee: Doosan Heavy Industries and Construction Co Ltd
Priority date: 2017-04-18
Filing date: 2017-09-26
Publication date: 2020-06-10
Anticipated expiration: 2037-09-26
Also published as: EP3392468A1; JP6475802B2; JP2018178986A; US20180298785A1; KR101902240B1

Description

BACKGROUND

The present invention relates to an exhaust diffuser and a gas turbine having the same and, more particularly, to an exhaust diffuser having variable vanes.

Description of the Related Art

In general, a gas turbine 10 comprises, as shown in FIG. 1, a compressor 15, a combustor 25, and a turbine 40. Air suctioned through an air inlet 20 is compressed into high-temperature and high-pressure compressed air by the compressor 15, high-temperature and high-pressure combustion gas (working fluid) is produced by combusting the compressed air by supplying fuel to the compressed air in the combustor 25, the turbine 40 is operated by the combustion gas, and a power generator connected to the compressor 15 is operated.
One of important aerodynamic problems during normal operation of a gas turbine engine 10 is to efficiently discharge combustion gas flowing out with high momentum through the last stage 60 of a turbine 40.
It may be aerodynamically advantageous to configure a horizontal exhaust line, but axial exhaust may be substantially impossible due to influence on the entire footprint.
For this reason, it is standard in the field to use vertical and side exhaust stacks that change the flow of combustion gas from an axial turbine into the radial direction.
In detail, a radial diffuser may be used to guide combustion gas into the radial direction.
A radial diffuser 100', as shown in FIG. 2, generally includes a plurality of struts 140' mounted on an internal diffuser guide 150' and surrounded by an external diffuser guide 130'.
The radial diffuser 100' changes the kinetic energy of the combustion gas flowing out through the last stage of the turbine into potential energy of increased static pressure. Increasing the entire restoration of static pressure increases the performance and efficiency of the entire gas turbine engine.
Accordingly, it has been required to develop an improved diffuser and an improved exhaust system to be used for gas turbine engines. Several technologies of removing flow separation by controlling the boundary layer of the flow at the inlet of a diffuser have been developed in correspondence to the requirement.
However, according to the technologies, it is impossible to remove flow separation between an internal diffuser guide and struts. Such flow separation causes a loss of pressure and consequently reduces the performance of the entire combustor.
Therefore, it is required to develop an exhaust diffuser that can solve the problems in the related art.

Documents of Related Art

(Patent Document 1) Korean Patent Application Publication No. 10-2015-0123950 (published on November 4, 2015 )
US 8776527 B1 discloses a discharge nozzle having a centerbody and a conduit enclosing the centerbody and is operable to receive exhaust flow from a turbine discharge of a gas turbine engine. US2013265848 A1 discloses a duct having flow conducting surfaces, with a flow guide surface arranged in the duct.

SUMMARY OF THE INVENTION

The present invention describes an exhaust diffuser according to claim 1. The performance of the exhaust diffuser is improved by controlling the profile of a velocity field at an inlet where exhaust gas flows into the exhaust diffuser, and a gas turbine having the exhaust diffuser. The vanes may be concentrically mounted and form a ring-shaped structure when viewed in a longitudinal section.
Two or more vanes may be mounted at a predetermined distance from each other on the struts.
The vanes may have a streamline structure or an airfoil structure when viewed in a longitudinal section.
The struts may have a streamline structure or an airfoil structure when viewed in a longitudinal section.
A guide projection extending in a flow direction of exhaust gas is formed on an outer side of the vane.
The guide projection has a streamline structure continuing from the outer side of each vane when viewed in a longitudinal section.
According to another aspect of the present invention, a gas turbine engine having the features of claim 6 is provided.
As described above, according to the exhaust diffuser of the present invention, since there are provided struts and rotary vanes that are formed in a specific structure, it is possible to effectively remove flow separation on the outer side of the internal diffuser guide by controlling the profile of a velocity field at an inlet where exhaust gas flows into the exhaust diffuser. Accordingly, it is possible to provide an exhaust diffuser of which performance is improved, and a gas turbine having the exhaust diffuser.
Further, according to the exhaust diffuser of the present invention, since the exhaust diffuser includes three or more struts spaced at a predetermined angle from each other around the outer side of the internal diffuser guide and vanes connecting adjacent struts and formed in a ring shape in a cross-section, it is possible to easily control radial inlet flow generated in an operation area. Accordingly, it is possible to improve performance of the exhaust diffuser by controlling the profile of a velocity field at an inlet where exhaust gas flows into the exhaust diffuser.
Further, according to the exhaust diffuser of the present invention, since the vanes and the struts have a streamline structure of an airfoil structure, it is possible to easily control the profile of a velocity field at an inlet of exhaust gas flowing in the exhaust diffuser.
Further, according to the exhaust diffuser of the present invention, since a guide projection is formed on the outer side of each vane, it is possible to effectively control the profile of a velocity field at an inlet of exhaust gas flowing in the exhaust diffuser.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the present invention will be more clearly understood from the following detailed description when taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a view showing the configuration of a gas turbine according to the related art;
FIG. 2 is a schematic view showing an exhaust diffuser according to the related art;
FIG. 3 is a perspective view showing an exhaust diffuser according to an embodiment of the present invention;
FIG. 4 is a cross-sectional view showing the exhaust diffuser according to an embodiment of the present invention;
FIG. 5 is a partial enlarged view showing a strut, a vane, and a driving unit according to an embodiment of the present invention;
FIG. 6 is a perspective view showing a vane and a guide projection according to another embodiment of the present invention; and
FIG. 7 is a cross-sectional view showing the vane and the guide projection shown in FIG. 6.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, preferred embodiments of the present invention are described in detail with reference to the drawings. The terms and words used in the present specification and claims should not be interpreted as being limited to typical meanings or dictionary definitions, but should be interpreted as having meanings and concepts relevant to the technical scope of the present invention.
It should be understood that when an element is referred to as being "on" another element, the elements may be in contact with each other or there may be an intervening element present. Through the present specification, unless explicitly described otherwise, "comprising" any components will be understood to imply the inclusion of other components rather than the exclusion of any other components.
FIG. 3 is a perspective view showing an exhaust diffuser according to an embodiment of the present invention and FIG. 4 is a cross-sectional view showing the exhaust diffuser according to an embodiment of the present invention.
Referring to the figures, an exhaust diffuser 100 according to the embodiment includes a hollow cylindrical internal diffuser guide 101 and an external diffuser guide 102 and further includes struts 110 and a rotary vane 120.
According to the present invention, since there are provided the struts 110 and the rotary vane 120 that have a specific structure, it is possible to effectively remove flow separation on the outer side of the internal diffuser guide 101 by controlling the profile of a velocity field at an inlet of exhaust gas flowing in the exhaust diffuser 100. Accordingly, it is possible to provide variable guide vanes that can improve performance of a diffuser, and a gas turbine having the vanes.
The components of the exhaust diffuser 100 according to the embodiment are described hereafter in detail with reference to the drawings.
The struts 110 according to the embodiment, as shown in FIGS. 3 and 4, are disposed between the internal diffuser guide 101 and the external diffuser guide 102 to space the internal diffuser guide 101 and the external diffuser guide 102 at a predetermined distance.
The struts 110 may have a streamline structure or an airfoil structure when viewed in a longitudinal section.
A specific number of struts 110 are shown in FIG. 3, but the number may be appropriately changed different from that shown in the figure in consideration of a pressure drop of the exhaust gas flowing in the exhaust diffuser 100.
The vanes 120 according to the embodiment surround the outer side of the internal diffuser guide 101 and are rotatably mounted on the struts 110. As shown in FIG. 3, two or more vanes 120 may be mounted on the struts 110 at predetermined distance from each other.
The vanes 120 are formed in a ring shape surrounding the internal diffuser guide 101.
The number and position of the vanes 120 may be appropriately changed in consideration of a pressure drop of the exhaust gas flowing in the exhaust diffuser 100.
Three or more struts 110 according to the embodiment may be spaced at a predetermined angle around the outer side of the internal diffuser guide 101. The vanes 120 connect adjacent struts 110 and may be formed to correspond to the outer side of the internal diffuser guide 101.
The vanes 120 may be sequentially mounted to form a ring-shaped structure when viewed in a longitudinal section.
FIG. 5 is a partial enlarged view showing a strut 110, a vane 120, and a driving unit 111 according to an embodiment of the present invention.
Referring to FIGS. 4 and 5, the vane 120 according to the embodiment is mounted on the strut 110 through a hinge unit 121. The driving unit 111 that operates with the hinge unit 121 of the vane 120 through a link 112 is disposed inside the strut 110.
According to the structure, the link 112 is moved by forward and backward rotation of the driving unit 111, so the vane 120 mounted through the hinge unit 121 is rotated clockwise or counterclockwise in the figures. That is, the angle of the vane 120 to flow of exhaust gas is changed by the hinge unit 121 and the link 112.
FIG. 6 is a perspective view showing a vane and a guide projection according to another embodiment of the present invention and FIG. 7 is a cross-sectional view showing the vane and the guide projection shown in FIG. 6.
Referring to the FIGS. 3, 6, and 7, a guide projection 122 extending in the flow direction of exhaust gas is formed on an outer side of the vane 120 according to the embodiment.
In detail, the guide projection 122, as shown in FIG. 7, forms a streamline shape continuing from the outer side of the vane 120 when viewed in the longitudinal section. Since the guide projection 122 is positioned on the vane 120 in the flow direction of exhaust gas flowing, the exhaust gas splits to the left and right of the guide projection 122. As the exhaust gas is split by the guide projection 122, it is possible to suppress flow separation that is promoted by the viscosity of surrounding exhaust gas. Accordingly, the guide projection 122 contributes to controlling the profile of a velocity field of the exhaust gas at an inlet.
Although one guide projection 122 is shown on one vane 120 in the figures, several guide projections 122 may be provided on one vane 120. In order to form a plurality of guide projections 122, it may be considered to make the gaps between the guide projections 122 different in consideration of the profile of the exhaust gas.
As described above, according to the exhaust diffuser of the present invention, since there are provided struts and rotary vanes that are formed in a specific structure, it is possible to effectively remove flow separation on the outer side of the internal diffuser guide by controlling the profile of a velocity field at an inlet where exhaust gas flows into the exhaust diffuser. Accordingly, it is possible to provide an exhaust diffuser of which performance is improved, and a gas turbine having the exhaust diffuser.
Further, according to the exhaust diffuser of the present invention, since the exhaust diffuser includes three or more struts spaced at a predetermined angle from each other around the outer side of the internal diffuser guide and vanes connecting adjacent struts and formed in a ring shape when viewed in a longitudinal section, it is possible to easily control radial inlet flow generated in an operation area. Accordingly, it is possible to improve performance of the exhaust diffuser by controlling the profile of a velocity field at an inlet where exhaust gas flows into the exhaust diffuser.
Further, according to the exhaust diffuser of the present invention, since the vanes and the struts have a streamline structure of an airfoil structure, it is possible to easily control the profile of a velocity field at an inlet of exhaust gas flowing in the exhaust diffuser.
Further, according to the exhaust diffuser of the present invention, since a guide projection is formed on the outer side of each vane, it is possible to easily control the profile of a velocity field at an inlet of exhaust gas flowing in the exhaust diffuser.
The present invention can also provide a gas turbine having the exhaust diffuser 100 of the present invention, so it is possible to improve performance of the exhaust diffuser by controlling the profile of a velocity field at an inlet where exhaust gas flows into the exhaust diffuser. Accordingly, it is possible to provide a gas turbine of which performance is improved.
Only specific embodiments of the present invention were described above. The present invention is limited to the scope of the claims.

Claims

An exhaust diffuser (100) for a gas turbine engine that is mounted at an outlet of a gas turbine to eject exhaust gas to outside of the turbine and includes a hollow cylindrical internal diffuser guide (101) and an external diffuser guide (102),
the exhaust diffuser (100) comprising:
a plurality of struts (110) disposed between the internal diffuser guide (101) and the external diffuser guide (102) to space the internal diffuser guide (101) and the external diffuser guide (102) at a predetermined distance from each other; and

a plurality of vanes (120) surrounding an outer side of the internal diffuser guide (101), wherein the plurality of vanes (120) are formed in a ring shape surrounding the internal diffuser guide (101), wherein three or more struts (110) are spaced at a predetermined angle from each other around the outer side of the internal diffuser guide (101),

the vanes (120) connect adjacent struts (110), and

the vanes (120) are arranged in parallel to the outer side of the internal diffuser guide (101), wherein the each of the plurality of vanes (120) is mounted on the plurality of struts (110) through a hinge unit (121), and

a driving unit (111) operating with the hinge unit (121) of the vane (120) through a link (112) is disposed in the strut (110),

characterized in that

one or more guide projections (122) extending in a flow direction of exhaust gas are formed on an outer side of the vanes (120), wherein the guide projection (122) has a streamline structure continuing from the outer side of each vane (120) when viewed in a longitudinal section.
The exhaust diffuser (100) of claim 1, wherein the vanes (120) are concentrically mounted and form a ring-shaped structure when viewed in a longitudinal section.
The exhaust diffuser (100) of claim 1, wherein two or more vanes (120) are mounted at a predetermined distance from each other on the struts (110).
The exhaust diffuser (100) of claim 1, wherein the vanes (120) have a streamline structure or an airfoil structure when viewed in a longitudinal section.
The exhaust diffuser (100) of claim 1, wherein the struts (110) have a streamline structure or an airfoil structure when viewed in a longitudinal section.
A gas turbine engine having an exhaust diffuser (100) according to any one of claims 1 to 5.