US 3778184 A
Damping of compressor or turbine vanes in the supporting shroud is accomplished by surrounding one end of the vane with a damping material of the steel wool or felt metal type held in contact with the shroud in which the vane is loosely supported.
Claims available in
Description (OCR text may contain errors)
United States Patent 11 1 1111 3,778,184
Wood 1 Dec. 11, 1973 1 VANE DAMPING 3,519,222 7/1970 Davis 415/174 3,071,346 1/1963 Broffit r 415/137 [751 Glasmnbury, 3,556,735 11/1963 Epelman 60/297 Conn.
 Ass1gnee: United Aircraft Corporation, East Primary Examiner camon R cmyle Hartford, Conn.
Assistant Examiner-Louis J. Casaregola  Filed: June 22, 1972 Att0rr7ey-Charles A. Warren  Appl. No.: 265,413
 11.8. C1. 415/174, 415/191  ABSTRACT W [511 E Fold 11/08 Fold 1/02 Fold 9/00 Damping of compressor or turbine vanes in the sup-  Fleld 01 Search 415/174, 219, 136, porting Shroud is accomplished by surrounding one 415/137 191; 416/190 500 end of the vane with a damping material of the steel wool or felt metal type held in contact with the shroud  References cued in which the vane is loosely supported. 1
UNITED STATES PATENTS 2,952,442 9/1960 Warnken 415/174 4 Claims, 2 Drawing Figures 'PAIENIEnnm 1 ma Z? M XX VANE DAMPING BACKGROUND OF THE INVENTION This invention relates to damping the vanes in a compressor or turbine.
Damping has been accomplished by positioning a thermoplastic or thermosetting material between the end of the vane and the supporting shroud or around the vane externally of the shroud with the damping material functioning as a bond between the vane and the shroud. Heat may be required in placing the material in the desired position around the vane ends and in some cases heat may be essential in curing the thermosetting material.
A feature of the present invention is a damping structure which requires no heating of the device or the material. Another feature is a damping structure in which the effectiveness of the damping may be controlled by more or less compressing the damping material prior to or during installation. Another feature is the damping of vane vibration by a material of the felt metal, steel wool or braided or knit wire type.
According to the present invention the row of vanes are secured to the inner shroud and extend loosely through slots in the outer shroud with the vane ends surrounded by damping material of the felt metal, steel wool or braided or knit wire type thus forming a damper for vane vibration. This material is different in structure and function from other damping material in that it is a resilient fibrous material with a significant porosity. This material is in contact with the sides of the vane adjacent to the ends of the vanes and may also be in contact with the outer ends of each of the vanes if so desired. The damping material is positioned between the shroud and a surrounding cover plate that holds it in position to accomplish the desired damping.
Other features and advantages will be apparent from the specification and claims and from the accompanying drawings which illustrate an embodiment of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an axial sectional viewthrough a vane assembly showing the damping materials therein. damping FIG. 2 is a fragmentary sectional view along the line 2-2 of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT A row of vanes 2 only one of which is shown in FIG. I are supported at their inner ends by an inner shroud ring 4 the vanes being brazed or welded or otherwise secured in slots 6 in this inner shroud ring.
Each of the vanes extends outwardly through a slot 8 in the outer shroud ring 10 and the outer end of the vane extends beyond the outer surface of the shroud ring as shown. The shroud ring 10 is preferably somewhat U-shaped in cross section having outwardly projecting flanges l2 and 14 with laterally projecting flange rings 16 and 18 thereon. The outer edges of the rings 16 and 1 8 may have attachment flanges 20 and 22 for securing the adjacent stages of compressor vanes thereto.
The outer end of each vane is received in a porous compressible pad 24 of felt metal, stainless steel wool, braided wire or knit wire which encircles the vane end tightly and extends over the tip of the vane. A sheet metal cover 26 attached as by rivets 28 to the shroud ring holds the damping material in place and may serve to preload the material against the vanes and acts as a seal. The compartment defined between the shroud ring 10 and the cover 26 is a fixed dimension within which the damping pad is compressed. When the vane vibrates energy is dissipated at the contact surface of the vane and damper and internally within the damper. This arrangement requires no structural restraint on the outer end of the vane with respect to the shroud and serves effectively to reduce vibratory stress levels.
The damping material may extend over a plurality of vanes or there may be a separate damping pad for each of the vane ends. In either event the cover plate 26 holds the pads in position and may be utilized to apply a predetermined load on the damping material thereby to control the effective damping action. It may be desirable to form the pad with a notch 30, F IG. 2, to receive the end of the vane although this :may be unnecessary in many instances depending on the length that the vane projects beyond the shroud ring and the amount of damping pressure that is to be applied to the end of the vane by the damping material.
A form of pad that has proved to be satisfactory for this purpose is a porous stainless steel single filament wire pad since it will be effective for a longer period of time at the hot end of a multistage axial flow compressor. Other wire pad structures in which the wires are feathered together are equally usable. It will be understood that the amount that the pad is compressed thereby reducing the porosity will determine the effectiveness of the damping action on the vane end. It should be noted that no particular preparation is necessary for the vane end since the wire pad is not attached to the vane positively in any way. It may be desirable to provide notches 32 and 34 at the leading and trailing edges of the vane at its outerend since this arrangement will serve to provide a broader surface for damping vibrations chordwise of the vane.
1. A turbine vane assembly including a row of turbine vanes extending in a generally radial direction about an axis,
an inner shroud to which the inner ends of the vanes are secured,
an outer shroud having openings therein through which the outer ends of the vanes project,
a porous wire mesh fabric forming a compressible pad surrounding and receiving therein the outer end of each vane on the outer side of the outer shroud for damping purposes, and
a band surrounding said outer shroud and overlying the outer ends of the vanes, said hand holding the wire mesh fabric in position, said band being se cured to said outer shroud.
2. A turbine vane assembly as in claim 1 in which said wire meash fabric is an open work material made up of a plurality of metallic wires feathered together to form a compressible mass.
3. A turbine vane assembly as in claim 1 in which said wire mesh extends around substantially the entire periphery of the outer shroud.
4. A turbine vane assembly as in claim 1 in wire mesh is in contact with both the sides and the end of each of the vanes.
I t 4 Q I which said I mg? l a v UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3,778,184 Dated December 11, 1973 n flslDonald H. Wood It is certified that error appears in theabove-identified patent and that said Letters Batent are hereby corrected as shown below:
Column 1, line 32, delete "may" line 32, delete "be" and insert --desirably-- lines 44-45, delete "damping" second 7 occurrence 7 Column 2, line 30, change "feathered' to --felted-- line 32, delete "thereb y reducing the porosity" line 58, change Y'meas h" to -n1esh-- line 59, 1 change "feathered" to --:Eelted-- Signed and sealed this 21st day of May 1971+.
(SEAL) Attest: I
'0. MARSHALL DAM Commissioner of Patents EQWAEPW QL Attesting Officer