The invention relates to a cooling system for actively cooling a turbine blade with a cooling fluid by way of a flow passage formed inside the turbine blade.
High temperature turbine blades with internal cooling frequently have the problem of flow separation in regions in which the flow passage or the flow direction of the cooling fluid is diverted. The possible separation of the cooling air flow at the inlet into the next flow passage section diminishes the cooling performance of the fluid and thus also has implications for the lifespan of the turbine blade. Apart from this, flow passages should otherwise be generally designed for an optimum coolant flow pattern.
An object of one aspect of the present invention provides a turbine blade with internal flow passage formed in the turbine blade, with which the problems are reduced and in particular the potential separation of the cooling air flow is avoided or minimised in regions in which the flow is diverted.
According to one aspect of the invention, a cooling system for actively cooling a turbine blade with a cooling fluid via an internal flow passage formed in the turbine blade is proposed. The flow passage extends from an inlet edge to an outlet edge and comprises a first passage section, which defines a first flow direction, and a second passage section, which defines a second flow direction. Furthermore, the flow passage comprises a wall and a diverter located between the first and second passage section, which is designed to transfer the flow from the first into the second direction. In the region of the diverter, the wall forms a pier head which, at least with a pier head section, extends into the region of the first passage section and thereby reduces the flow cross section of the flow passage in a specific manner as intended. By way of this, the flow of the cooling fluid is accelerated before the diverter. The consequence of this is that the flow can flow into the next flow passage without any or only minor separation by the diverter.
Preferentially, the cooling system is designed so that the flow passage comprises a second diverter at the end of the second passage section, which opens into a third passage section and a second wall between the second and third passage section, which is formed with a second pier head which at least with a pier head section that extends into the region of the second passage section, and because of this likewise specifically reduces the flow cross section of the flow passage in a comparable manner. By way of this, the flow of the cooling fluid is again accelerated before the diverter and the flow at this point can also flow into the next flow passage without any or with only minor separation by the diverter.
In an advantageous embodiment version it is provided that the pier head, viewed in the cross section, is circular arc-shaped, curved or drop-shaped at least in an end-side section and extends in the direction of the first passage section. The extension of the face-end section in the direction of the first passage section brings about the desired cross-sectional constriction and the circular arc-shaped, curved or drop-shaped profile a contour that is optimal for the flow control.
In an alternative exemplary embodiment of the invention it is provided that the pier head, viewed in the cross section, is formed, at least in a face-end section, of a plurality of linear and/or bent polynomial sections and extends in the direction of the first passage section. With suitable arrangement of linear and/or bent polynomial sections, the surface for the flow control can be further optimised.
Favourable, furthermore, is an embodiment in which the outer contour of the first pier head, viewed in the flow direction, extends as follows: commencing from the linearly extending wall of the first passage section with a curvature section, which curves in the direction of the passage section, merging into a part circular arc section of opposite curvature, which in turn merges into the linearly extending wall of the second passage section at the outlet of the diverter, however without the outer contour projecting into the second passage section. By way of this, the flow cross section in the diverter is not changed by the wall at least at the outlet but maintained at this flow edge.
In a further advantageous version it is provided according to the invention that the outer contour of the second pier head viewed in the flow direction extends as follows: commencing from the linearly extending wall of the second passage section with a curvature section, which curves in the direction of the passage section, merging into a part circle-shaped arc section of opposite curvature, which in turn merges into the linearly extending wall of the third passage section at the outlet of the diverter however without the outer contour projecting into the third passage section.
The cooling system according to one aspect of the invention is designed so that the turbine blade comprises an annular space between a lower and upper blade contour, which defines the gas-conducting surface of the turbine blade.
It is advantageous, furthermore, when the center of the pier head is arranged in a region which is arranged offset relative to the annular space within the lower or upper blade contour, in a manner of speaking offset towards the outside opposite the annular space.
In a further development of the present cooling system it is provided, furthermore, that the flow passage comprises an inlet, which forms an opening for receiving the cooling fluid in the flow passage, and a blow-out, which forms an opening for letting the cooling fluid out of the flow passage.
In a preferred embodiment of the invention, the turbine blade comprises a multiplicity of inlet openings in the region of the inlet edge for letting the cooling fluid into the flow passage, which are arranged spaced from one another. Through the multiplicity of the inlet openings, the cooling fluid can be received in the flow passage over the entire width of the turbine blade as a result of which the turbine flow is optimised.
The turbine blade preferentially comprises a multiplicity of outlet openings for letting the cooling fluid out of the flow passage, which are arranged spaced from one another. Through the multiplicity of the inlet openings, the cooling fluid can be let out of the flow passage over the entire width of the turbine blade.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.
Other advantageous further developments of the invention are characterized in the subclaims and are shown in more detail in the following by way of the figures together with the description of the preferred embodiment of the invention.
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In the following, the invention is described by way of an exemplary embodiment making reference to
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In this embodiment, the invention is not restricted to the preferred exemplary embodiments stated above. A number of versions is also conceivable which make use of the shown solution even with embodiments of fundamentally different types.
Thus, while there have shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.
Number | Date | Country | Kind |
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DE102018119572.9 | Aug 2018 | DE | national |