US3588278A - Blade structure for an axial flow elastic fluid utilizing machine - Google Patents

Blade structure for an axial flow elastic fluid utilizing machine Download PDF

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Publication number
US3588278A
US3588278A US809242A US3588278DA US3588278A US 3588278 A US3588278 A US 3588278A US 809242 A US809242 A US 809242A US 3588278D A US3588278D A US 3588278DA US 3588278 A US3588278 A US 3588278A
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United States
Prior art keywords
blades
rotor
speed
frequency
resonant
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Expired - Lifetime
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US809242A
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English (en)
Inventor
Ralph J Ortolano
William P Welch
Harold W Semar
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Cooper Laboratories Inc
Westinghouse Electric Corp
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Westinghouse Electric Corp
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Assigned to COOPER LABORATORES, INC. reassignment COOPER LABORATORES, INC. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: BAXTER TRAVENOL LABORATORIES, INC., A CORP. OF DE
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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
    • F01D5/22—Blade-to-blade connections, e.g. for damping vibrations
    • F01D5/24—Blade-to-blade connections, e.g. for damping vibrations using wire or the like
    • 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
    • F01D5/22—Blade-to-blade connections, e.g. for damping vibrations
    • F01D5/225—Blade-to-blade connections, e.g. for damping vibrations by shrouding

Definitions

  • ABSTRACT The invention provides an improved bladed rotor structure for an axial flow turbine, or the like, operable at constant or variable speed within a speed range extending to maximum rated speed, wherein the vibratory stress at resonant speeds is substantially reduced by connecting the blades to each other, as by shroud or lashing structure in groups equal in number to the resonant harmonic frequency of tee blades divided by the resonant speed.
  • the vibratory stresses on rotor blades for turbines or the like may be substantially minimized in the tangential inphase mode by connecting the blades to each other in groups by lashing structure or shrouding structure divided into arcuate segments of substantially equal arcuate extent and equal in number to the lowest harmonic frequency of the blades that it is desirable to suppress.
  • the blades are connected into groups by shroud ring structure or lashing structure equal in length to the length of one cycle of tangential vibration of the harmonic frequency that is to be suppressed.
  • rotor blades operating at the fourth harmonic frequency would be provided with four 90 shroud ring segments or four 90 lashing structures, while rotor blades operating at the sixth harmonic frequency would be provided with six 60 shroud ring segments or lashing structures, etc.
  • the first type of excitation of a high frequency excitation and therefore resonance questions are primarily considered on the small or initial blades of the turbine which typically have a high vibrating frequency.
  • the second type of excitation is most severe when the blades have a vibrating frequency that is a low multiple of the rotor speed in cycles per second. This is the type of blade vibration with which the invention is concerned.
  • FIG. 1 is a fragmentary view of a turbine rotor having blades provided with shroud segments in accordance with the inven tion;
  • FIG. 2 is a radial sectional view, on a larger scale, taken along line ll-Il of FIG. 1;
  • FIG. 3 is a diagrammatic view of an unshrouded bladed rotor structure, showing the blades in fourth harmonic vibration;
  • FIG. 4 is a diagram showing the fourth harmonic frequency occurrence in the rotor of FIG. 3;
  • FIG. 5 is a chart showing relative amplitude of vibration of the blades plotted against a ratio of harmonic frequency of rotor running speed to number of shroud segments in a blade row;
  • FIG. 6 is a view similar to FIG. 1, but showing a lashed rotor blade structure
  • FIG. 7 is a radial sectional view, on a larger scale, taken along line VII-VII of FIG. 6.
  • FIG. 1 there is shown a portion of a turbine rotor 10 comprising a rotor spindle 11 having an array of radially extending blades 12 supported therein and connected to each other in arcuate groups by arcuate shroud members or segments 13.
  • the spindle 11 is of circular cross section and the blades 12 are arranged in an annular circumferential array about the rim 14 of the spindle.
  • the blades 12 may be connected to the rotor rim 14 in any desirable manner. However, as best illustrated in FIG. 2, the blades are formed with bulbous l-shaped roots 15 received in a mating peripheral groove 16 formed in the spindle rim 14.
  • the blades are provided with air foil vane portions 17 extending radially outwardly from the roots l5 and are further provided with tenons 18 extending through uniformly spaced holes 19 and secured to the shroud segments 13 by deformation of the tenons as by riveting.
  • the structure is substantially conventional, and, in operation as steam or other motive fluid is directed past the turbine rotor blades 12 by the stationary nozzle vanes (not shown) the rotor 10 is rotated, as well known in the art.
  • the blades are susceptible to serious and damaging vibration at frequencies which are harmonies of a resonant running speed of the turbine rotor.
  • Two of the most common causes ofblade vibration excitation are:
  • the first type of excitation is a high frequency excitation and therefore resonant frequencies occurring as high multiples of rotor speed are primarily considered in short blades, typically formed in the early stages of expansion in the turbine.
  • the second type of excitation is a lower frequency excita' tion and therefore resonant frequencies occurring as low multiples of rotor speed are primarily considered in the longer blades typically found in the later stages of expansion in the turbine.
  • the invention is concerned with this type ofvibration.
  • the pattern of deflection of the row of blades 12, without the shroud segments 13, will be a function of some multiple of turbine rotor speed. For example, if the blades have a fundamental vibration frequency of 400 c.p.s. and the rotor is rotating at 6000 rpm. or I00 r.p.s., by substitution in the above formula,
  • the above phenomenon manifests itself on the unshrouded blades 12 as illustrated in FIG. 3, as four complete cycles of vibration, each extending across the blades disposed in the arcuate group extending across a central angle of 90.
  • one halfof the blades in each group are deflecting in one tangential direction and the other half are deflecting in the opposite tangential direction. That is, one half of the blades are going through half of the fourth harmonic vibration cycle (-HQF, while the other half of the blades are going through the other halfof the fourth vibration cycle /2F Therefore, if the blades are isolated into four separate arcuate systems or groups, the excitation forces supplied to the blades in each group, above, have a cancelling effect.
  • the blades 12 are formed into such groups by connecting them to each other by shroud segments 13 extending peripherally to the same extent.
  • shroud segments 13 extending peripherally to the same extent.
  • the blades have a fundamental vibration frequency such that at a running speed of the rotor they are operable in another harmonic, for example the sixth harmonic, then there will be six vibration waves at any one instant occurring in the blades, each vibration extending across the blades included in 1/6 of 360 or 60 and six 60 shroud segments would be employed to dampen such blade vibrations.
  • any plurality of shroud ring segments, in accordance with the invention, equal to, or lower than, the expected harmonic frequency of rotor running speed will result in a ratio of F /N' greater than one, so that the blades are never operable in the high amplitude range (below unity).
  • FIGS. 6 and 7 show another embodiment of the invention wherein a rotor structure 50 is provided with an annular row of unshrouded blades 52 that are connected to each other in arcuate groups by suitable lashing structure 54 and 55.
  • the lashing structure 54 and 55 connects the blades to each other at two points along their radiallength in the embodiment shown.
  • the number of lashing structures may be modified as desired. For example only one lashing structure may be employed, or alternately, more than two, depending on the length and size of the blades, for example.
  • the arcuate lengthof the lashing structure 54 and/or 55 is selected in the same manner as the arcuate shroud ring segments to suppress the same resonant harmonic frequencies of the blades. That is, for the fourth harmonic, four lashing structures of angular extend are employed, etc.
  • the lashing structure 54 and 55 may be of any type, as well known in the prior art, and in a similar manner, the shroud ring structure 13 may be of any type, as well known in the art.
  • a rotor structure for an axial flow elastic fluid utilizing machine comprising a rotor spindle,
  • said blades being susceptible to vibrate in a tangential inphase mode having a resonant frequency at least twice that of the rated maximum running speed of said rotor
  • said connecting means dividing the blade groups into a number equal to said resonant frequency divided by said rotor running speed.
  • connecting means comprises arcuate shroud ring structure attached to the radially outermost tips of the blades.
  • connecting means comprises lashing structure connecting the blades to each other intermediate their inner and outer ends.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Turbine Rotor Nozzle Sealing (AREA)
US809242A 1969-03-21 1969-03-21 Blade structure for an axial flow elastic fluid utilizing machine Expired - Lifetime US3588278A (en)

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US80924269A 1969-03-21 1969-03-21

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GB (1) GB1265464A (enrdf_load_stackoverflow)

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3795462A (en) * 1971-08-09 1974-03-05 Westinghouse Electric Corp Vibration dampening for long twisted turbine blades
US4386887A (en) * 1980-06-30 1983-06-07 Southern California Edison Company Continuous harmonic shrouding
US4662824A (en) * 1984-10-01 1987-05-05 Ortolano Ralph J Sleeve connectors for turbines
US4710102A (en) * 1984-11-05 1987-12-01 Ortolano Ralph J Connected turbine shrouding
USRE32737E (en) * 1980-06-30 1988-08-23 Southern California Edison Continuous harmonic shrouding
US4776764A (en) * 1987-04-02 1988-10-11 Ortolano Ralph J Structure for an axial flow elastic fluid utilizing machine
US5257908A (en) * 1991-11-15 1993-11-02 Ortolano Ralph J Turbine lashing structure
US5498136A (en) * 1993-09-17 1996-03-12 Hitachi, Ltd. Fluid machinery having blade apparatus and blade apparatus for fluid machinery
US5540551A (en) * 1994-08-03 1996-07-30 Westinghouse Electric Corporation Method and apparatus for reducing vibration in a turbo-machine blade
US20090214345A1 (en) * 2008-02-26 2009-08-27 General Electric Company Low pressure section steam turbine bucket
US20150176413A1 (en) * 2013-12-20 2015-06-25 General Electric Company Snubber configurations for turbine rotor blades
US10760592B1 (en) * 2017-01-17 2020-09-01 Raytheon Technologies Corporation Gas turbine engine airfoil frequency design
US10760429B1 (en) * 2017-01-17 2020-09-01 Raytheon Technologies Corporation Gas turbine engine airfoil frequency design
US10788049B1 (en) * 2017-01-17 2020-09-29 Raytheon Technologies Corporation Gas turbine engine airfoil frequency design
US10982551B1 (en) 2012-09-14 2021-04-20 Raytheon Technologies Corporation Turbomachine blade
US11199096B1 (en) 2017-01-17 2021-12-14 Raytheon Technologies Corporation Turbomachine blade
US11293289B2 (en) * 2017-03-13 2022-04-05 Siemens Energy Global GmbH & Co. KG Shrouded blades with improved flutter resistance
US11698002B1 (en) * 2017-01-17 2023-07-11 Raytheon Technologies Corporation Gas turbine engine airfoil frequency design
US11767763B1 (en) * 2017-01-17 2023-09-26 Raytheon Technologies Corporation Gas turbine engine airfoil frequency design

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3706170C2 (de) * 1987-02-26 1997-08-14 Pierburg Ag Seitenkanalpumpe

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3795462A (en) * 1971-08-09 1974-03-05 Westinghouse Electric Corp Vibration dampening for long twisted turbine blades
US4386887A (en) * 1980-06-30 1983-06-07 Southern California Edison Company Continuous harmonic shrouding
USRE32737E (en) * 1980-06-30 1988-08-23 Southern California Edison Continuous harmonic shrouding
US4662824A (en) * 1984-10-01 1987-05-05 Ortolano Ralph J Sleeve connectors for turbines
US4710102A (en) * 1984-11-05 1987-12-01 Ortolano Ralph J Connected turbine shrouding
US4776764A (en) * 1987-04-02 1988-10-11 Ortolano Ralph J Structure for an axial flow elastic fluid utilizing machine
US5257908A (en) * 1991-11-15 1993-11-02 Ortolano Ralph J Turbine lashing structure
US5498136A (en) * 1993-09-17 1996-03-12 Hitachi, Ltd. Fluid machinery having blade apparatus and blade apparatus for fluid machinery
US5540551A (en) * 1994-08-03 1996-07-30 Westinghouse Electric Corporation Method and apparatus for reducing vibration in a turbo-machine blade
US20090214345A1 (en) * 2008-02-26 2009-08-27 General Electric Company Low pressure section steam turbine bucket
US10982551B1 (en) 2012-09-14 2021-04-20 Raytheon Technologies Corporation Turbomachine blade
US20150176413A1 (en) * 2013-12-20 2015-06-25 General Electric Company Snubber configurations for turbine rotor blades
US10760592B1 (en) * 2017-01-17 2020-09-01 Raytheon Technologies Corporation Gas turbine engine airfoil frequency design
US10760429B1 (en) * 2017-01-17 2020-09-01 Raytheon Technologies Corporation Gas turbine engine airfoil frequency design
US10788049B1 (en) * 2017-01-17 2020-09-29 Raytheon Technologies Corporation Gas turbine engine airfoil frequency design
US11199096B1 (en) 2017-01-17 2021-12-14 Raytheon Technologies Corporation Turbomachine blade
US11698002B1 (en) * 2017-01-17 2023-07-11 Raytheon Technologies Corporation Gas turbine engine airfoil frequency design
US11767763B1 (en) * 2017-01-17 2023-09-26 Raytheon Technologies Corporation Gas turbine engine airfoil frequency design
US11293289B2 (en) * 2017-03-13 2022-04-05 Siemens Energy Global GmbH & Co. KG Shrouded blades with improved flutter resistance

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AS Assignment

Owner name: COOPER LABORATORES, INC., 3145 PORTER DRIVE, PALO

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:BAXTER TRAVENOL LABORATORIES, INC., A CORP. OF DE;REEL/FRAME:004067/0785

Effective date: 19820917