BRIEF DESCRIPTION OF THE DRAWINGS
Preferred developments of the invention result from the description hereinafter. Examples of the invention, without being restricted thereto, are explained in detail with reference to the drawings. They show in:
FIG. 1 illustrates a damping arrangement for guide vanes of a gas turbine, i.e., an aircraft engine, in accordance with prior art;
FIG. 2 is an exploded view of a damping arrangement for guide vanes of a gas turbine, i.e., an aircraft engine, within the meaning of the present invention; and
FIG. 3 is an assembled view of a section of the damping arrangement as in FIG. 2 of the region of the inner shroud of a guide vane.
DETAILED DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view of a condenser 10 of a gas turbine 11, in the region of two guide vane rings 12, as well as three rotor blade rings 13. Viewed in axial direction or in flow direction (arrow 14), guide vane rings 12 and rotor blade rings 13 are alternately arranged.
Each of the guide vane rings 12 consists of several guide vanes 15 arranged in circumferential direction at a distance from each other. The guide vanes 15 of the guide vane rings 12 are mounted on a radially external end 16 to a housing 17 of the condenser 10. On a radially internal end 18, the guide vanes 15 of the guide vane rings 12 form an inner shroud 19. At least one seal bearing 20 for the seal elements 21 is mounted to the inner shrouds 19 of the guide vanes 15. The seal elements 21 are configured as honeycomb seals which interact with seal fins 23 associated with rotor disks 22.
Referring to FIG. 1, prior art has disclosed damping the guide vanes 15 of the guide vane rings 12 on the inner shrouds 19 with respect to vibration stress in that a spring element 25 is positioned in a hollow space 24 located between the inner shrouds 19 of the guide vanes 15 and the, or each, seal bearing 20. Referring to prior art, this spring element 25 is configured as a C-shaped spring, which results in a relatively large radial design in the region of the inner shroud 19. Referring to FIG. 1, the radial design height in the region of the inner shroud 19, as well as the seal bearing 20, is indicated by a double arrow 26. Such a large radial design height in the region of the inner shroud results in a radially large design height of the entire gas turbine. This is disadvantageous. Furthermore, referring to prior art, the known C-shaped spring elements are subject to tolerances and thus imprecise.
Hereinafter, referring to FIGS. 2 and 3, the inventive damping arrangement will be described in greater detail, in which case FIG. 2 represents an exploded view of the damping arrangement, and FIG. 3 represents a cross-section through the inventive damping arrangement in the region of the inner shroud of a guide vane.
FIG. 2 shows a sectional view of a guide vane ring 27 in the region of four guide vanes 28. A radially externally abutting end 29 of the guide vanes 28 is used to mount the guide vanes to a housing of the gas turbine, which is not shown in FIG. 2. Referring to a radially internally located end 30 of the guide vanes 28, the guide vanes form an inner shroud 31. A seal bearing 32 for the seal elements 33 can be mounted to the four guide vanes 28.
Within the meaning of the present invention, it has been suggested to provide at least one spring element 34 configured as a leaf spring between the inner shroud 31 of the guide vanes 28 and the seal bearing 32 in order to achieve a damping of the guide vanes 28 in the region of the inner shrouds 31. Referring to FIG. 3, the spring element 34 configured as a leaf spring is positioned in a hollow space 35 between the inner shroud 31 and the seal bearing 32. Due to the minimal radial extension of the spring element 34 configured as a leaf spring, the hollow space 35 may also be embodied in a design having minimal radial height, so that, overall, the radial design height of the gas turbine is reduced.
As can be learned from FIG. 3, the spring element 34 is clamped between the inner shrouds 31 of the guide vanes 28 and the seal bearings 32 in such a manner that the spring's central abutment section 36 abuts against the seal bearing 32 and the spring's two lateral abutment sections 37 and 38 abut, or are in contact with, the inner shroud 31. Consequently, within the meaning of the arrows of FIG. 3, damping forces caused by vibrations act on the spring element 34. It should be noted that the abbreviation F in FIG. 3 stands for “Force.” At this point it should be pointed out that the spring element 34 can also be clamped in exactly the reverse manner between the inner shrouds 31 of the guide vanes 28 and the seal bearing 32, namely, in such a manner that the central abutment section 36 of the spring element 34 abuts against the inner shroud 31, and that the two lateral abutment sections 37 and 38 abut against the seal bearing 32.
Referring to FIG. 2, the spring element 34 configured as the leaf spring comprises—in the depicted embodiment—more than four leaf spring sections 39 which are separated from each other by slits 40. Consequently, such a leaf spring section 39 is positioned in the region of each inner shroud 31 of each guide vane 28. Consequently, each guide vane 28 is individually damped in the region of the respective inner shroud 31. As can be learned from FIG. 2, the individual leaf spring sections 39 are separated from each other by respectively two slits 40, each of the two slits 40 extending from a different side into the spring element 34. The slits 40, which extend from different sides into the spring element 34 and which separate two adjacent leaf spring sections 39 from each other, end at a distance from each other, so that, between the two slits 40, a connecting strip remains between two leaf spring sections 39.
Referring to FIGS. 2 and 3, the inventive seal arrangement additionally comprises securing elements 41, which extend in circumferential direction and are located between the inner shrouds 31 of the guide vanes 28 and the seal bearing 32. The securing elements 41 are configured as securing wires and—viewed in cross-section—extend laterally next to the, or each, spring element 34 that is configured as a leaf spring. The securing elements 41 are guided in appropriate cutouts 42 and 43, respectively, inside the inner shroud 31 or the seal bearing 32. On its one end, the spring element 34 has angled sections 44 that act as securing tabs and fix the securing elements 41 in position.
Within the meaning of the present invention, a particularly advantageous design of a damping arrangement for the guide vanes of a gas turbine is provided. The radially minimal design height, as well as the easy manufacture of the spring elements, are particularly advantageous. Considering their uninstalled and thus relaxed state, the spring elements are configured as a simple, flat metal sheet. Therefore, the manufacture of the, or each, spring element does not require any bending. The spring forces or the deformation of the, or each, spring element is determined, among other things, by the contour of the inner shroud of the guide vanes and by the contour of the, or each, seal bearing.
Patent Application
20080019836
