Abstract: A method and apparatus for maintaining integrally bladed rotors (IBR) includes using first vibration data from a IBR vibration apparatus of a first IBR to determine a set of values for a corresponding set of inherent vibratory properties based on a reduced order model for an IBR type to which the first IBR belongs. Shape data indicating an initial shape of a surface of a first blade is used, with repair data that indicates a candidate repair to form a restored shape, to determine a change in a value of an inherent blade section vibratory property of the set of inherent vibratory properties. A condition of the first IBR is determined based at least in part on the change in the value of the inherent blade section vibratory property. The first IBR is maintained based on the condition.

Abstract: A method and apparatus for maintaining integrally bladed rotors (IBR) includes using first vibration data from a IBR vibration apparatus of a first IBR to determine a set of values for a corresponding set of inherent vibratory properties based on a reduced order model for an IBR type to which the first IBR belongs. Shape data indicating an initial shape of a surface of a first blade is used, with repair data that indicates a candidate repair to form a restored shape, to determine a change in a value of an inherent blade section vibratory property of the set of inherent vibratory properties. A condition of the first IBR is determined based at least in part on the change in the value of the inherent blade section vibratory property. The first IBR is maintained based on the condition.

Abstract: A method and apparatus for maintaining integrally bladed rotors (IBR) includes using first vibration data from a IBR vibration apparatus of a first IBR to determine a set of values for a corresponding set of inherent vibratory properties based on a reduced order model for an IBR type to which the first IBR belongs. Shape data indicating an initial shape of a surface of a first blade is used, with repair data that indicates a candidate repair to form a restored shape, to determine a change in a value of an inherent blade section vibratory property of the set of inherent vibratory properties. A condition of the first IBR is determined based at least in part on the change in the value of the inherent blade section vibratory property. The first IBR is maintained based on the condition.

Abstract: A bladed rotor system includes a circumferential row of blades mounted on a rotor disc. Each blade includes an airfoil and a shroud attached to the airfoil at a span-wise height of the airfoil. The row of blades includes a first set of blades and a second set of blades. The airfoils in the first and second set of blades have substantially identical cross-sectional geometry about a rotation axis. The blades of the second set are distinguished from the blades of the first set by a geometry of the shroud that is unique to the respective set, whereby the natural frequency of a blades in the first and second sets differ by a predetermined amount. Blades of the first set and the second set alternate in a periodic fashion in said circumferential row, to provide a frequency mistuning to stabilize flutter of the blades.

Abstract: A reduced order model of an integrally bladed turbine disk (IBD) is used with experimental vibrational test data to modify a finite element model (FEM) of the IBD so that the FEM more accurately predicts the vibrational mistuning of the disk. The refined FEM can be used to evaluate a proposed modification of the IBD before the hardware is actually modified, and to evaluate the actual modification if there is a difference between the proposed and actual modifications.

Abstract: A bladed rotor system (10) includes a circumferential row of blades (14) mounted on a rotor disc (12). Each blade (14) includes an airfoil (16) and a shroud (30) attached to the airfoil (16) at a span-wise height of the airfoil (16). The row of blades (14) includes a first set (H) of blades (14) and a second set (L) of blades (14). The airfoils (16) in the first (H) and second (L) set of blades (14) have substantially identical cross-sectional geometry about a rotation axis (22). The blades (14) of the second set (L) are distinguished from the blades (14) of the first set (H) by a geometry of the shroud (30) that is unique to the respective set (H, L), whereby the natural frequency of a blades (14) in the first (H) and second (L) sets differ by a predetermined amount. Blades (14) of the first set (H) and the second set (L) alternate in a periodic fashion in said circumferential row, to provide a frequency mistuning to stabilize flutter of the blades (14).

Abstract: A method and system for establishing sets of blade frequency values for each rotating blade of a rotor assembly at two or more different points in time and determining an indication of blade health from the change in the blade frequency values is provided. Blade frequency values are determined by receiving measurements of vibratory responses from blade monitoring equipment (20) and processing via a processing device (30) vibration data as a system of rotating blades to extract a frequency of each blade. Sets of blade frequency values are compared to determine a change in the blade frequency values for each rotating blade to provide the indication of blade health.

Abstract: A method and system for establishing sets of blade frequency values for each rotating blade of a rotor assembly at two or more different points in time and determining an indication of blade health from the change in the blade frequency values is provided. Blade frequency values are determined by receiving measurements of vibratory responses from blade monitoring equipment (20) and processing via a processing device (30) vibration data as a system of rotating blades to extract a frequency of each blade. Sets of blade frequency values are compared to determine a change in the blade frequency values for each rotating blade to provide the indication of blade health.

Abstract: An extended version of a reduced order model called the Fundamental Mistuning Model (FMM) accurately predicts vibratory response and damping in a bladed disk system. The extended FMM software may describe the normal modes and natural frequencies of a mistuned bladed disk as well as damping in the disk using complex-valued inputs of its tuned system frequencies and the frequency mistuning of each blade/disk sector (i.e., the sector frequencies). The extended FMM system identification methods—basic and advanced extended FMM ID methods—also use complex mistuned modes and complex frequencies of the mistuned bladed disk as inputs. As a result, in extended FMM ID calculations, the tuned system frequencies and the mistuning frequency ratios are complex numbers. The real parts of frequencies relate to sector frequencies as well as tuned system frequencies. However, the imaginary part can be related to system damping.

Abstract: A reduced order model called the Fundamental Mistuning Model (FMM) accurately predicts vibratory response of a bladed disk system. The FMM software may describe the normal modes and natural frequencies of a mistuned bladed disk using only its tuned system frequencies and the frequency mistuning of each blade/disk sector (i.e., the sector frequencies). The FMM system identification methods—basic and advanced FMM ID methods—use the normal (i.e., mistuned) modes and natural frequencies of the mistuned bladed disk to determine sector frequencies as well as tuned system frequencies. FMM may predict how much the bladed disk will vibrate under the operating (rotating) conditions. Field calibration and testing of the blades may be performed using traveling wave analysis and FMM ID methods. The FMM model can be generated completely from experimental data. Because of FMM's simplicity, no special interfaces are required for FMM to be compatible with a finite element model.

Abstract: A reduced order model called the Fundamental Mistuning Model (FMM) accurately predicts vibratory response of a bladed disk system. The FMM software may describe the normal modes and natural frequencies of a mistuned bladed disk using only its tuned system frequencies and the frequency mistuning of each blade/disk sector (i.e., the sector frequencies). The FMM system identification methods—basic and advanced FMM ID methods—use the normal (i.e., mistuned) modes and natural frequencies of the mistuned bladed disk to determine sector frequencies as well as tuned system frequencies. FMM may predict how much the bladed disk will vibrate under the operating (rotating) conditions. Field calibration and testing of the blades may be performed using traveling wave analysis and FMM ID methods. The FMM model can be generated completely from experimental data. Because of FMM's simplicity, no special interfaces are required for FMM to be compatible with a finite element model.

Abstract: This invention relates to the construction of a turbine rotor having a rotor disc with a plurality of blades, said blades having roots fitted into slots around the periphery of the disc with each blade engaging a stop means to properly position it, said blades being held in place by a cover plate fixed to the rotor disc and said stop means; a pocket is formed on the front face of each blade while an annular groove on said cover plate is positioned over said circumferential ring of pockets. Each pocket has an outer flat surface placed at an angle so that each surface intersects the outer surface of the annular groove; a stiff solid damper having a rectangular surface is positioned in each pocket so that one end of said surface will be supported by the outer surface of the annular groove while the other end of said surface will be supported by the outer surface of the pocket when the damper is thrown outwardly by centrifugal force.