US2917274A - Compressor and turbine blades - Google Patents

Compressor and turbine blades Download PDF

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Publication number
US2917274A
US2917274A US304975A US30497552A US2917274A US 2917274 A US2917274 A US 2917274A US 304975 A US304975 A US 304975A US 30497552 A US30497552 A US 30497552A US 2917274 A US2917274 A US 2917274A
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United States
Prior art keywords
blade
elements
metal
contact
tip
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Expired - Lifetime
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US304975A
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English (en)
Inventor
Davidson Ivor Macaulay
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Power Jets Research and Development Ltd
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Power Jets Research and Development Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
    • F01D5/12—Blades
    • F01D5/14—Form or construction
    • F01D5/16—Form or construction for counteracting blade vibration
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
    • F01D5/12—Blades
    • F01D5/14—Form or construction
    • F01D5/147—Construction, i.e. structural features, e.g. of weight-saving hollow blades
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S416/00—Fluid reaction surfaces, i.e. impellers
    • Y10S416/50—Vibration damping features

Definitions

  • the blade fixed at its root and free at its tip, constitutes a loaded cantilever.
  • This cantilever must be fairly substantial so as to.withstand both the static gas loading and also the dynamic loadingwhich tends to cause vibration, a condition which is in opposition to the two requirements of lightness and thinness.
  • the present invention consists essentially in a blade formed of at least two layers engaging each other by contact surfaces extending along the .blade'length, from tip to root, and fastened immovably together at one end but left free along the rest of the blade length for one layer to move longitudinally over another.
  • the invention provides in a bladed rotary fluid flow machine, a blade having an attachment end and a tip at its respective longitudinal extremities which blade comprises at least first and second elements coextensive in length into which the blade is divided from the attachment end to the tip thereof, at least said first element being initially bowed to afford a concave contacting surface said blade including means securing said blade elements together at the attachment end of the blade only with said contacting surface of said first blade element constrained into contact with said second blade element whereby said first blade element is deflected and parts of said blade elements radially outward of their attachment ends are free to move over one another under the mutual constraint of their contact. 7
  • the aforesaid mutual constraint under which the contacting surfaces of the partsof the blade elements are free to move over one another may be supplemented by means of an intervening layer serving to increase the friction between the contacting surfaces.
  • Such means may comprise an intervening third element of rubbery material, the initially concave surface of one metal blade element and the other metal blade element being constrained into contact with opposite sides of the rubbery material.
  • Figure l is a view of a lengthwise section through the complete blade
  • Figure 3 is a view of a lengthwise section through the complete blade before being completely assembled
  • Figure 4 is a sectional view of a machine, for example a compressor, incorporating the blade of Figures 1-3,
  • FIG. 1 is an isometric view of the mounted blade of Figures 1 and 2, I I
  • Figure 6 is a projected view showing a modification of the blade of Figures 1 to 3 in which the contact surface is roughened
  • Figure 7 is a view corresponding to Figure 1 of a further modified blade of this invention having an intermediate layer of friction material
  • Figures 8 and 9 are views corresponding to Figures 3' and 2 of a further modified blade of this'invention having the concave surface of one blade element coated with a rubber material.
  • the'laminated blade consists of two metal blade elements, 1 and 2 into which the blade is divided along its length, from tip to root, and across its width (as shown in Fig. 2) substantially chordwise from leading to trailing edge. The division continues down through theroot of the blade, which is separated into more or less equal attachment ends 1a and 2a locked together against relative radial movement e.g. by key 2b of one element engaging groove 1b in the other bladeelement. 7
  • the metal blade elements are secured together at the root but not elsewhere and so the laminae are free to slide slightly over each other on flexure of the assembled blade, as in a laminated spring.
  • the attachment ends or root parts 1a and 2a are rivetted togethere.g. by rivet 3 through the base of the blade and n'vet 4 through the bottom of the'r'oot-- but these rivets will only need to be heavy enough to hold the parts together during assembly; when the blades are mounted in the machine the parts will be held together by the anchoring of the root in its seating.
  • the blade elements '1 and 2 are initially bowed so that when brought together as in Figure 3 they are in- 'clined towards each other; when rivetted up and so clamped together in contact, the blade elements are each elastically deflected and pre-stressed to such a degree that they do not separate under the action of the gas load.
  • a sample blade can be made up of laminae which are'shaped initially to the desired final shape shown in Fig. 1, so that they will fit together without deflection and pre-stressing, to give the desired blade shape.
  • Each blade element, apart from the other one, is then separately loaded to subject it to the estimated contact force but in a sense which will produce stresses opposite in sign from the desired pre-stressing; this will deflect the blade element to the shape to which it should be pre-formed. Accordingly, this deflected blade element can be used as a master pattern of the correct shape to which the blade elements should be made.
  • the elements 1 and 2 will beof metal.
  • the friction between the metal in contact can be artificially increased by roughening as shown in Figure 6 or coating the rubbing surfaces of the elements as shown in Figure 7.
  • a thin layer of frictional material usually non-metallic, and possible textile or fibrous material, shown at 5 in Fig. 7, can be inserted between or form part of adjacent metal elements.
  • a thin layer 6 of rubbery materialsuch as natural orsynthetic rubber can be bonded to at least'one of the metal elements.
  • this bonded layer may serve as a cement to hold the metal laminae temporarily together.
  • the thickness and strength of the bonded layer may be either such that on application of a bending load to the blade, the cement fails in shear, after which it serves as the frictional coating between the relatively slidable layers, or such that the layer serves permanently to hold the metal elements together, the necessary relative longitudinal movement of the metal laminae being permitted by shear strain of the rubbery material, which thus serves to supply the necessary damping in place of frictional damping due to rubbing of the laminae.
  • attachment ends forming the root can be of any of the suitable forms, such as a bulbous root, it is indicated in the drawings as a tapered and serrated root of so-called fir-tree form.
  • the invention consists in a fabricated metal blade permitting bending of the blade under load by very free but highly damped relative movement between layers of metal extending chordwise along the blade length from root to tip.
  • the division through the blade lies transversely to the blade thickness; the division is shown in the drawings as extending chordwise and passing through the leading edge and the trailing edge of the blade, but this is merely by way of example of one possible manner of division.
  • the blade profile may be such that the surface which passes chordwise through each section of the blade and equally divides each section, from tip to root is substantially a surface generated by a radius of the rotor of the machine in which the blade is to be used; centrifugal force acting alone will then produce substantially no bending or twisting moment on an undeflected blade, and will tend to restore a deflected blade. In such case a dividing surface between laminae 1 and 2 coincides with the said camber sheet.
  • the surface of separation may be chosen to cut the external surface of the blade at positions displaced from the blade edges, so as to maintain an unbroken external surface of the blade along its length at around at least the leading edge, especially of a compressor blade.
  • the edges of the blade elements where they meet at or near the leading edge of the blade may have their sharpness removed by slight rounding.
  • Final machining of the blade and of its root to its finished shapee.g. by grinding may be done after assembly of the separate parts.
  • the invention by reducing the stresses in blades, may make possible the use of aluminium or like light alloy castings for compressor blades and these can then be precision die castings, requiring little or no external machining.
  • a bladed rotary fluid flow machine including a blade having an attachment end and a tip at its respective longitudinal extremities which blade comprises at least first and second elements co-extensive in length into which the blade is divided from the attachment end of the tip thereof, at least said first element being initially bowed to afford a concave contacting surface, said blade including means securing said blade elements together at the attchment end of the blade only with said contacting surface of said first blade element constrained into contact with said second blade element whereby said first blade element is deflected and parts of said blade elements radially outward of their attachment ends are free to move over one another under the mutual constraint of their contact.
  • a bladed rotary fluid flow machine including a blade having an attachment end and a tip at its respective longitudinal extremities which comprises a plurality of blade elements. extending from the attachment end to the tip of the blade into which the latter is divided, said elements including at least two metal elements and an intervening third element of rubbery material, at least one of said metal elements being bowed to afford a concave contact surface on its side adjacent the other metal element, said machine including, means securing said blade elements together at the attachment end of the blade only with said initially concave surface and the said other metal element constrained into contact with opposite sides of said rubbery layer whereby said initially bowed element is deflected and parts of said metal elements radially spaced from said attachment ends are free to move relatively under the constraint of their contact with said rubbery layer.
  • a bladed rotary fluid flow machine including a blade having an attachment end and a tip at its respective longitudinal extremities, which blade comprises at least first and second elements co-extensive in length into which the blade is divided from the attachment end to the tip thereof, at least said first element being initially bowed to afford a concave contacting surface, said machine including means securing said blade elements together at the attachment end of the blade only with said contacting surface of said first blade element constrained into contact with said second plate element whereby said first blade element is deflected and parts of said blade elements radially outward of said attachment end are free to move over one another under the mutual constraint of their contact.
  • a bladed rotary fluid flow machine including a blade having an attachment end and a tip at its respective longitudinal extremities, said blade being divided in two substantially equal first and second blade elements from the attachment end to the tip, said blade elements being co-extensive in length and whereof at least said first element is initially bowed to aiford a longitudinally concave surface on its side adjacent said second element, said machine including means securing said blade elements together at the attachment end only with said first blade element being deflected by said securing means into frictional engagement with said second blade element, whereby parts of said first and second blade elements spaced from said attachment end are able to move over one another relatively to one another under their mutual friction constraint.
  • a bladed rotary fluid flow machine as claimed in claim 5 in which a third element constitued by a separate layer of friction material is interposed between said first and second blade elements.
  • a bladed rotary fluid flow machine including a blade having an attachment end and a tip at its respective longitudinal extremities which comprises a plurality of blade elements extending from the attachment end to the tip of the blade into which the latter is divided, said elements including at least two metal elements at least one of said metal elements being bowed to afford a concave contact surface adjacent the other element, said machine including means securing said blade elements together at the attachment end of the blade only thereby to draw said initially concave surface into frictional engagement with the adjacent surface of the other element whilst allowing parts of said elements spaced from said attachment end to move relative to each other under frictional constraint and including means between said elements for supplementing the frictional constraint tending to restrict such movement of said elements.
  • a bladed rotary fluid flow machine as claimed in claim 7 in which said means between said elements for supplementing frictional constraint includes an artificial roughening of one of the two adjacent surfaces of said blade elements.
  • a bladed rotary fluid flow machine as claimed in claim 7 in which a third element is interposed between said first and second elements, said third element comprising a layer of friction material and said securing means serving to constrain said first and second elements into frictional contact with said third element whilst allowing parts of said first and second elements spaced from said securing means free to move relatively under the constraint of their contact with said third element.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Architecture (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)
US304975A 1951-08-31 1952-08-18 Compressor and turbine blades Expired - Lifetime US2917274A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB313851X 1951-08-31

Publications (1)

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US2917274A true US2917274A (en) 1959-12-15

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US (1) US2917274A (enrdf_load_html_response)
CH (1) CH313851A (enrdf_load_html_response)
DE (1) DE971286C (enrdf_load_html_response)
FR (1) FR1068776A (enrdf_load_html_response)
NL (1) NL81240C (enrdf_load_html_response)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3796513A (en) * 1972-06-19 1974-03-12 Westinghouse Electric Corp High damping blades
US4118147A (en) * 1976-12-22 1978-10-03 General Electric Company Composite reinforcement of metallic airfoils
US4462755A (en) * 1981-08-24 1984-07-31 The United States Of America As Represented By The Secretary Of The Navy Anvil-strap rotor
FR2682992A1 (fr) * 1991-10-23 1993-04-30 Snecma Aubage de turbomachine en materiau composite a matrice a base d'un elastomere.
US5356264A (en) * 1991-12-26 1994-10-18 General Electric Company Viscoelastic vibration damper for engine struts
US20070041840A1 (en) * 2004-03-08 2007-02-22 Alstom Technology Ltd. Rotor end piece

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB246801A (en) * 1925-01-31 1926-03-18 Nieuport Astra Sa Improvements in or relating to aerial propellers
US2340133A (en) * 1940-12-14 1944-01-25 United Aircraft Corp Propeller blade
US2394124A (en) * 1943-02-13 1946-02-05 Gen Electric Bladed body
US2412615A (en) * 1943-04-16 1946-12-17 Gen Electric Bladed machine element

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2317338A (en) * 1942-02-07 1943-04-20 Westinghouse Electric & Mfg Co Turbine blade fastening apparatus
BE470026A (enrdf_load_html_response) * 1945-12-21

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB246801A (en) * 1925-01-31 1926-03-18 Nieuport Astra Sa Improvements in or relating to aerial propellers
US2340133A (en) * 1940-12-14 1944-01-25 United Aircraft Corp Propeller blade
US2394124A (en) * 1943-02-13 1946-02-05 Gen Electric Bladed body
US2412615A (en) * 1943-04-16 1946-12-17 Gen Electric Bladed machine element

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3796513A (en) * 1972-06-19 1974-03-12 Westinghouse Electric Corp High damping blades
US4118147A (en) * 1976-12-22 1978-10-03 General Electric Company Composite reinforcement of metallic airfoils
US4462755A (en) * 1981-08-24 1984-07-31 The United States Of America As Represented By The Secretary Of The Navy Anvil-strap rotor
FR2682992A1 (fr) * 1991-10-23 1993-04-30 Snecma Aubage de turbomachine en materiau composite a matrice a base d'un elastomere.
US5356264A (en) * 1991-12-26 1994-10-18 General Electric Company Viscoelastic vibration damper for engine struts
US20070041840A1 (en) * 2004-03-08 2007-02-22 Alstom Technology Ltd. Rotor end piece
US7309214B2 (en) 2004-03-08 2007-12-18 Alstom Technology Ltd Rotor end piece

Also Published As

Publication number Publication date
CH313851A (de) 1956-05-15
FR1068776A (fr) 1954-06-30
NL81240C (enrdf_load_html_response) 1955-11-15
DE971286C (de) 1959-01-08

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