Method for balancing a turbofan engine or other rotating system

Patent metadata

Field	Value
Publication number	US-10145265-B2
Application number	US-201715416794-A
Country	US
Kind code	B2
Filing date	Jan 26, 2017
Priority date	May 8, 2012
Publication date	Dec 4, 2018
Grant date	Dec 4, 2018

Abstract

A method for balancing rotating machinery, such as gas turbine engines, to minimize vibrations. The method involves operation of the engine for a period of time at varying power levels and ranges of other operational parameters representative of the system operating envelope to obtain vibration data (amplitude and phase) for the full range of dynamic responses of interest. This usually includes time at elevated power settings until the engine reaches thermal stability, altitude variation, etc. as well as the full engine operating range. The full set of vibration data measured during the engine run is analyzed to generate unique unbalance states. The unique unbalance states are then analyzed and the mean unbalance state is identified. Balancing masses can then be installed or removed in accordance with a balance solution that is equal and opposite to the mean unbalance state.

First claim

The invention claimed is:

1. A system comprising:
an engine comprising a rotating system;
a plurality of balancing masses attached to the rotating system, which plurality includes a first subset of balancing masses attached to the rotating system at a time prior to calculation of a mean unbalance state of the first subset and a second subset of balancing masses attached to the rotating system at a time subsequent to calculation of a mean unbalance state of the first subset;
a plurality of vibration sensors attached to the engine; and
a computer system programmed to perform the following operations:
(a) acquiring vibration sensor data from the vibration sensors during rotation of the rotating system while the first subset of balancing masses are attached to the rotating system and the second subset of balancing masses are not attached to the rotating system;
(b) converting the vibration sensor data output from the vibration sensor during operation (a) into vibration data points, the vibration data points comprising amplitude and phase data;
(c) calculating respective unbalance states for the vibration data points resulting from operation (b);
(d) identifying unbalance states calculated in operation (c) which differ from each other by at least a threshold amount; and
(e) calculating a mean unbalance state having a magnitude and an angle using unbalance states identified in operation (d),
wherein the second subset of the plurality of balancing masses have respective masses and locations which, when treated as respective vectors originating at an axis of rotation and summed, have a vector sum equal to a mass-length equivalent of the mean unbalance state calculated during operation (e) at a phase angle 180 degrees from the angle associated with the mean unbalance state.

2. The system as recited in claim 1 , further comprising memory having a set of influence coefficients that are characteristic of a model of the engine stored therein, wherein the computer system is further programmed to perform the following operation:
deriving influence coefficients from the set of influence coefficients,
wherein operation (c) comprises vector multiplication of vibration data points times the derived influence coefficients.

3. The system as recited in claim 2 , wherein the derived influence coefficients are a function of at least a shaft speed of the engine at the time when the respective vibration data point was acquired.

4. The system as recited in claim 1 , wherein the rotating system is a gas turbine engine.

5. The system as recited in claim 4 , wherein the gas turbine engine is mounted to an aircraft.

6. The system as recited in claim 1 , wherein the rotating system comprises an internal turbofan engine component having an outer periphery with a plurality of threaded holes located around the outer periphery, and the plurality of balancing masses comprise respective balancing screws threadably inserted into respective threaded holes of the plurality of threaded holes.

7. The system as recited in claim 1 , wherein the balancing masses have different masses.

8. A system comprising:
an engine comprising a rotating system;
a plurality of balancing masses attached to the rotating system;
a plurality of vibration sensors attached to the engine; and
a computer system programmed to perform the following operations:
(a) acquiring vibration sensor data from the vibration sensors during rotation of the rotating system while none of the plurality of balancing masses are attached to the rotating system;
(b) converting the vibration sensor data output from the vibration sensor during operation (a) into vibration data points, the vibration data points comprising amplitude and phase data;
(c) calculating respective unbalance states for the vibration data points resulting from operation (b);
(d) identifying unbalance states calculated in operation (c) which differ from each other by at least a threshold amount; and
(e) calculating a mean unbalance state having a magnitude and an angle using unbalance states identified in operation (d),
wherein the plurality of balancing masses have respective masses and locations which, when treated as respective vectors originating at an axis of rotation and summed, have a vector sum equal to a mass-length equivalent of the mean unbalance state calculated during operation (e) at a phase angle 180 degrees from the angle associated with the mean unbalance state.

9. The system as recited in claim 8 , further comprising memory having a set of influence coefficients that are characteristic of a model of the engine stored therein, wherein the computer system is further programmed to perform the following operation:
deriving influence coefficients from the set of influence coefficients,
wherein operation (c) comprises vector multiplication of vibration data points times the derived influence coefficients.

10. The system as recited in claim 9 , wherein the derived influence coefficients are a function of at least a shaft speed of the engine at the time when the respective vibration data point was acquired.

11. The system as recited in claim 8 , wherein the rotating system is a gas turbine engine.

12. The system as recited in claim 11 , wherein the gas turbine engine is mounted to an aircraft.

13. The system as recited in claim 8 , wherein the rotating system comprises an internal turbofan engine component having an outer periphery with a plurality of threaded holes located around the outer periphery, and the plurality of balancing masses comprise respective balancing screws threadably inserted into respective threaded holes of the plurality of threaded holes.

14. The system as recited in claim 8 , wherein the balancing masses have different masses.

Assignees

• Boeing Co

Inventors

• Skilton Timothy L
• Pittenger Kevin J

Classifications

• F05D2260/96

  Preventing, counteracting or reducing vibration or noise · CPC title

• F05D2220/36

  specially adapted for the fan of turbofan engines · CPC title

• F01D21/003

  Arrangements for testing or measuring (for measuring vibrations G01H) · CPC title

• F01D21/045

  special arrangements in stators or in rotors dealing with breaking-off of part of rotor · CPC title

• G01M1/32

  by adding material to the body to be tested, e.g. by correcting-weights · CPC title