The present invention relates to a blade of a guide vane or of a rotor blade of a fluid flow machine according to the definition of the species set forth in claim 1. The present invention also relates to a fluid flow machine according to the definition of the species set forth in claim 13.
The European Patent EP 0 798 447 B1 describes a blade for fluid flow machines, in particular for gas turbines, which extends radially in a ring channel or flow channel, adjacently to at least one defining side wall of the ring channel, the blades exhibiting a thickened portion of the blade profile that is beneficial from a standpoint of fluid mechanics. In accordance with the EP 0 798 447 B1, this thickened portion is formed by an enlarged leading-edge nose radius and/or an enlarged leading-edge wedge angle and/or an enlarged trailing-edge wedge angle and/or an enlarged absolute profile thickness of profile sections adjacent to the defining side wall, as compared to a reference profile section. By employing blades having this type of design, guide vanes, as well as rotor blades, and, respectively, guide vane rings as well as rotor blade rings can be provided whose blade geometry influences a secondary flow in order to minimize the blade losses. However, the drawback associated with such a blade geometry is that the thickened portion necessitates an increased overall axial length of the blade and thus, ultimately, of the entire fluid flow machine.
Against this background, the object of the present invention is to devise a novel type of blade of a guide vane or of a rotor blade of a fluid flow machine.
This objective is achieved by a blade as set forth in claim 1. In accordance with the present invention, the thickened portion is cut in the area of one leading edge of the blade, forming a mirror surface or a basal plane.
It is provided along the lines of the present invention for the or each thickened portion of a blade to be cut in the area of one leading edge of the blade, forming a mirror surface or a basal plane. As a result, the decisive advantage is derived over the related art that secondary flow losses are minimized without having to elongate the overall axial length of the blades and thus of the fluid flow machine. In this respect, the present invention makes it possible to achieve a compact design of the fluid flow machine, while, at the same time, minimizing the secondary flow losses in the fluid flow machine.
In accordance with one advantageous embodiment of the present invention, a straight or plane cut is made in the thickened portion, in the area of the leading edge, in such a way that the cutting direction of the cut extends circumferentially or transversely to the axial direction of the fluid flow machine.
One alternative advantageous embodiment of the present invention provides for a circular segment-shaped or cylindrical segment-shaped cut to be introduced into the thickened portion in the area of the leading edge in such a way that a tangent line placed at the frontmost portion of the cut extends circumferentially or transversely to the axial direction of the fluid flow machine.
The or each thickened portion is preferably formed by a large radius of curvature at the radially inside end region and/or at the radially outside end region of the blade, the ratio of the radius of curvature to a chord length of the blade being between 2% and 10%.
The fluid flow machine according to the present invention is defined in independent claim 13.
Preferred embodiments of the present invention are derived from the dependent claims and from the following description. The present invention is described in greater detail in the following on the basis of exemplary embodiments, without being limited thereto. Reference is made to the drawing, whose figures show:
Prior to describing the present invention in greater detail with reference to
In accordance with
It should be noted here that thickened portion 11 shown in
It should also be noted here that, in the case of rotor-mounted rotating rotor blades, the blades are provided with such thickened portions 11 only on the radially inside, hub-side end. On the other hand, if it is a question of fixed guide vanes, then, typically, they each have a thickened portion 11 of this kind, both on the radially inside, hub-side end, as well as on the radially outside, housing-side end.
The present invention provides for thickened portion 11 to be cut in the area of leading edge 12 of blade 10, forming a mirror surface 14 or a basal plane. This is illustrated in particular in
In the exemplary embodiment of
The combination of a thickened portion having large radius of curvature r and the cutting of thickened portion 11 in the area of leading edge 12, forming a mirror surface 14, makes it possible to minimize secondary flow losses without having to elongate the overall axial length of the blade or of the fluid flow machine.
Common to the exemplary embodiment according to
The blades according to the present invention are preferably used for guide vanes or rotor blades of a turbine or of a compressor of a gas turbine, in particular of a gas turbine aircraft engine. As previously mentioned, the blades of rotating rotor blades have thickened portions in accordance with the present invention merely in the area of the hub-side end. Fixed guide vanes may have a thickened portion of this kind both on the radially inside, hub-side end, as well as on the radially outside, housing-side end. In accordance with the present invention, the thickened portions are cut in the area of the leading edge, forming a mirror surface or a basal plane. The present invention also provides for a large radius of curvature to be used. This makes it possible, on the one hand, to minimize secondary flow losses without, on the other hand, having to increase the overall axial depth or length of the fluid flow machine equipped with such blades.
Number | Date | Country | Kind |
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10 2004 026 386.8 | May 2004 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/DE05/00788 | 4/29/2005 | WO | 11/28/2006 |