Compressor rotor blade

A compressor rotor blade (1) includes a rotor blade (2), a platform (3) that adjoins the rotor blade (2) and blade footing (4) that adjoins the platform (3). The rotor blade (4) is embodied so as to be massive, without an internal cooling system, and exhibits a leading and a trailing edge (5, 6), a suction and a compression side, as well as a blade tip (7). The compressor rotor blade (1) is distinguished by virtue of the fact that the rotor blade (2) of the compressor rotor blade (1) exhibits a recess (8) on the trailing edge (6) of the blade tip (7).

This application claims priority under 35 U.S.C. § 119 to German application number 103 52 253.0, filed 8 Nov. 2003, the entirety of which is incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a compressor rotor blade.

2. Brief Description of the Related Art

A compressor rotor blade in keeping with this type is known from European patent EP 0 991 866 B1. Such compressor rotor blades have the disadvantage that as a result of the excitation of high frequencies (lyra mode), they are made to oscillate in such a manner that the profiled tips, in particular, are exposed to an elevated mechanical stress. This can lead to considerable damage of the compressor rotor blades, even to breaking.

SUMMARY OF THE INVENTION

Therefore, the task of creating an extension of a compressor rotor blade such that the oscillatory behavior described above is diminished exists, so that damage as a consequence of excessive mechanical stress is precluded. The measures in question that are to be taken are to be as simple as possible in terms of construction and as cost-effective as possible in their realization.

According to principles of the present invention, this task can be resolved by a compressor rotor blade.

An underlying aspect of the present invention includes equipping the rotor blade with a recess at the blade tip, in an area in front of the trailing edge of the rotor blade. At the blade tip, proceeding from the blade's leading edge, the rotor blade exhibits, first of all, an untouched area, which makes a transition, by means of a shoulder in the form of a step or a rounding, to a recess extending as far as the trailing edge of the rotor blade.

In the case of a compressor rotor blade according to the invention, damages at the tip of the rotor blade tip due to the lyra mode are avoided to good advantage on the side of egress.

Only those characteristics that are essential to the invention are shown.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1shows an embodiment of a compressor rotor blade1according to the invention, which comprises a rotor blade2, a platform3and a blade footing4. The compressor rotor blades1are arranged across the circumference of a rotor (not depicted). They are not connected by means of a cover band. The rotor blade2of compressor rotor blade1exhibits a rotor blade tip2, a leading edge5, a trailing edge6, as well as compression and a suction side. The compressor rotor blade1is configured massively and it exhibits no internal cooling system. According to the invention, the rotor blade2of compressor rotor blade1is equipped with a recess8at the blade tip7. This recess8extends across an area of the blade tip7on the egress side, as far as the trailing edge6, whereby the untouched length l1of the leading edge5of the compressor rotor blade1to the beginning of the recess constitutes 20% to 60%, preferably 30% to 50%, and particularly preferably, between 30% and 40% of the axial chord length of the compressor rotor blade1. The transition from the untouched area of the blade tip7to the recess8is accomplished by means of a shoulder9in the form of a step, whereby, to avoid indentation effects, the edges of the shoulder9are embodied with a radius R1of about 2 mm to 5 mm. The surface of the blade within the recess8runs substantially parallel to the original contour of blade tip7, which is indicated in the Figures by lines of dashes. The depth h1of the recess8is about 5% to 10% of the height H of the trailing edge6. With this compressor rotor blade1according to the invention, damage to blade tip7at the egress side, due to the lyra mode at high frequencies, is avoided.

FIG. 2shows an additional embodiment of a compressor rotor blade1according to the invention, whose essential characteristic consists of a recess8of the blade tip7on the egress side, configured as a rounding off10. The transition from the blade tip7to the trailing edge6is constructed in the form of a rounding off10with a radius R2, whereby R2corresponds to 0.5 to 1.5 times the chord length of blade1. According to one favorable variant, blade tip7makes the transition to a radius R2in the trailing edge6, which corresponds to the chord length. The area of the untouched length l2of blade tip7amounts, in this case, to about 50% to 80%, preferably 60% to 70% of the chord length. The depth h2of the recess8on the trailing edge will regularly lie beneath 30%, especially under 20%, preferably between 10% and 20% of the length of the trailing edge6.

According to an additional alternative embodiment of a compressor rotor blade1according toFIG. 3, the blade tip on the egress side is formed by a slope11, which makes the transition, in each case, through a rounding off having a radius R3at one end, to the blade tip7, and at the other end, to the trailing edge6. The slope11assumes an angle α of 20° to 60°, preferably of 30° to 45° to the trailing edge6. In this embodiment, too, the untouched length l3of blade tip7is about 50% to 80%, preferably 60% to 70% of the axial chord length of blade12. The depth h3of the recess8on the trailing edge6lies below 30%, preferably between 10% and 20% of the height H of the trailing edge6. With this compressor rotor blade1according to the invention, in addition, damage to the blade tip on the egress side due to the lyra mode at high frequencies is avoided.

The saving in mass that results from recess8on the compressor rotor blade1is approximately identical in the embodiments according to theFIGS. 1 through 3.

List of Reference Symbols

H Height of the trailing edge6

h1Depth of recess on trailing edge6

h2Depth of recess on trailing edge6

h3Depth of recess on trailing edge6

While the invention has been described in detail with reference to exemplary embodiments thereof, it will be apparent to one skilled in the art that various changes can be made, and equivalents employed, without departing from the scope of the invention. Each of the aforementioned documents is incorporated by reference herein in its entirety.