Apparatus for eliminating compressor stator vibration induced by tip leakage vortex bursting
Vibration induced compressor vane failure from tip leakage vortex bursting is eliminated or minimized. By securing the vane at opposite ends to inner and outer stationary casings, tip leakage is entirely avoided hence avoiding the mechanism for inducing vibration. By contouring the inner surface of the flow path to converge the flow in a downstream direction with a cantilevered compressor vane having a vane tip spaced from the inner casing surface, airflow lift off is precluded or minimized maintaining the flow attached to the flowpath surfaces with consequent avoidance of tip vortex induced vibration.
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The present invention relates to stator vanes in a compressor between inner and outer stationary components and particularly relates to apparatus for minimizing or eliminating tip leakage vortex bursting.
BACKGROUND OF THE INVENTIONIn compressors for turbines, stator vanes are typically mounted on a fixed or stationary casing surrounding a compressor rotor mounting buckets. Thus, air flowing into the compressor is compressed and heated for flow to various components of the turbine. At the aft end of the compressor, the stator vanes fixed to the outer stationary component are cantilevered in a radial inward direction and have tips spaced from an inner stationary component. These stator vanes at the aft end of the compressor are typically used to straighten the flow from the compressor. As the compressed air flows through the flow path defined between the inner and outer stationary components, a portion of the compressed air flows about the tip of the cantilevered stator vanes from the high pressure side to the low pressure side of each of vane, i.e. from the concave side to the convex side. As the flow passes between the tip and the inner stationary component, however, it forms a vortex. Under certain aerodynamic conditions, it has been discovered that the vortex as it bursts from the vane tips can cause a frequency of vibration in the stator vanes which reinforces the blade natural frequency. This can lead to failure of the compressor stator vanes. Accordingly, there is a need for apparatus which will minimize or eliminate tip leakage vortex bursting with consequent induced vibration such that stator vane failure resulting from such induced vibration does not occur.
BRIEF DESCRIPTION OF THE INVENTIONIn a preferred embodiment of the invention there is provided a compressor comprising: inner and outer stationary casings; and a plurality of stator vanes extending between and secured at radially opposite ends to said inner and outer casings thereby eliminating tip leakage between opposite sides of each stator vane and stator vane vibration induced by tip leakage vortex bursting
In a preferred embodiment of the invention, there is also provided a compressor comprising: a stator vane segment including a plurality of stator blades and inner and outer stationary shrouds about the blades eliminating tip leakage along the inner shroud and between opposite sides of the inner ends of the stator blades.
In a further preferred embodiment of the invention, there is provided a compressor comprising: a stator vane segment including a plurality of stator blades and a radial outer shroud, a stationary inner casing spaced from a tip of the stator blades and having a contoured surface exposed to the flow path for converging the flow in a downstream direction.
BRIEF DESCRIPTION OF THE DRAWINGS
Referring now to
As illustrated in
To minimize or eliminate this possibility, and referring to
In another aspect of the present invention as illustrated in
While it will be appreciated that each stator vane 46 may be fixed to both the outer and inner bands and hence tip leakage is avoided thereby also eliminating the excitation source, i.e., the tip leakage vortex, it is also possible to minimize the occurrence of stator vane tip leakage vortex vibration induced vane failure notwithstanding a gap between tips of cantilevered stator vanes and the opposed inner casing. That is, the stator vanes 46 can remain cantilevered with tips spaced from the inner casing provided the inner casing is contoured to preclude lift off of the tip leakage vortex. Thus, if the tip leakage vortex cannot lift off the contoured surface because of the convergent flow in the downstream direction, and remains attached to the inner and outer flow path defining surfaces, vibration induced by tip leakage vortex bursting is minimized or eliminated. In
While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
Claims
1. A compressor comprising:
- inner and outer stationary casings; and
- a plurality of stator vanes extending between and secured at radially opposite ends to said inner and outer casings thereby eliminating tip leakage between opposite sides of each stator vane and stator vane vibration induced by tip leakage vortex bursting.
2. A compressor comprising:
- a stator vane segment including a plurality of stator blades and inner and outer stationary shrouds about the blades secured to inner and outer ends of the blades respectively, thereby eliminating tip leakage along the inner shroud and between opposite sides of inner ends of the stator blades.
3. A compressor according to claim 2 wherein the inner and outer shrouds define a convergent flow path between adjacent stator blades to minimize or eliminate flow lift off from at least one of said inner and outer surfaces.
4. A compressor according to claim 3 wherein the inner shroud has upstream and downstream surfaces, said downstream surfaces extending radially outwardly relative to an axis of the compressor a greater distance than upstream surfaces enabling a convergent flow path.
5. A compressor comprising:
- a stator vane segment including a plurality of stator blades and a radial outer shroud, and a stationary inner casing spaced from a tip of the stator blades and having a contoured surface exposed to the flow path for converging the flow in a downstream direction.
Type: Application
Filed: Mar 7, 2005
Publication Date: Sep 7, 2006
Applicant: General Electric Company (Schenectady, NY)
Inventors: Steve Schirle (Anderson, SC), Robert Zacharias (Fountain Inn, SC), James Cencula (Neenah, WI), Nicholas Martin (Simpsonville, SC), Thomas Tipton (Simpsonville, SC)
Application Number: 11/072,249
International Classification: F04D 29/66 (20060101);