TURBINE ENGINE STALL WARNING SYSTEM

• US 20070261492A1
• Filed: 05/04/2007
• Published: 11/15/2007
• Est. Priority Date: 05/12/2006
• Status: Active Grant

• Current Assignee: Curtiss-Wright Flow Control Corporation (Curtiss-Wright Corporation)
• Original Assignee: Curtiss-Wright Flow Control Corporation (Curtiss-Wright Corporation)
• Inventors: Board, David B.
• Granted Patent: US 7,698,942 B2
• Time in Patent Office: Days
• US Class Current: 73/587
• CPC Class Codes: F04D 27/001 Testing thereof; Determination or simulation of flow characteristics; Stall or surge detection, e.g. condition monitoring
• CPC Class Codes: G01M 13/028 Acoustic or vibration analysis
• CPC Class Codes: G01M 15/14 Testing gas-turbine engines or jet-propulsion engines

Abstract

A Stall Warning System (SWS) utilizing the detection and analysis of stress waves, (i.e., ultrasound) emitted by combustion and/or turbulent flow processes of an apparatus, such as a turbine engine, for example. Upon detection of an impending stall condition, the SWS can inform the operator, inform another electronic device (computer, etc.) and/or latch the event for review by maintenance personnel.

Claims

1. A method for predicting an impending stall event for an apparatus, said method comprising the steps of:

monitoring stress waves generated by the apparatus during operation of the apparatus;

processing said stress waves to generate derived values;

comparing said derived values to a threshold value; and

generating an impending stall signal based on said comparing.

2. The method of claim 1, wherein said stress waves have a frequency above the hearable spectrum.

3. The method of claim 1, wherein said stress waves have a frequency of greater than 20 kHz.

4. The method of claim 3, wherein said stress waves have a frequency of less than 100 kHz.

5. The method of claim 1, wherein said stress waves have a frequency of less than 100 kHz.

6. The method of claim 1, wherein said stress waves are centered around a frequency of about 38 kHz.

7. The method of claim 1, wherein

said step of monitoring stress waves includes the steps of:

providing a first sensor to monitor a first series of stress waves, and providing a second sensor to monitor a second set of stress waves;

and wherein said step of processing said stress waves to generate derived values includes the steps of;

processing said first series of stress waves to generate a first series of stress wave energy values,

processing said second series of stress waves to generate a second series of stress wave energy values, and

calculating a difference between said first series of stress wave energy values and said second series of stress wave energy values to generate said derived values.

8. The method of claim 7, wherein said stress waves have a frequency between 20 kHz and 100 kHz.

9. The method of claim 1, wherein said impending stall signal is used to generate an impending stall notification to an operator of the apparatus.

10. A method for predicting an impending stall event for an apparatus, said method comprising the steps of:

monitoring a first part of the apparatus to detect a first series of stress waves;

monitoring a second part of the apparatus to detect a second series of stress waves;

processing said first series of stress waves to generate a first series of stress wave energy values;

processing said second series of stress waves to generate a second series of stress wave energy values;

calculating a difference between said first series of stress wave energy values and said second series of stress wave energy values to generate energy difference values;

comparing said energy difference values to a threshold value;

comparing said first series of stress wave energy values to a normal operating value; and

generating an impending stall signal when both of;

said difference values cross said first threshold value and said first series of stress wave energy values are near said normal operating values.

11. The method of claim 10, wherein the apparatus is a turbine engine.

12. The method of claim 10, wherein an impending stall notification is not issued when said first series of stress wave energy values fall outside said normal operating values.

13. The method of claim 10, wherein said impending stall signal is used to generate an impending stall notification to an operator of the apparatus.

14. The method of claim 10, wherein said stress waves have a frequency of greater than 20 kHz.

15. A system for predicting an impending stall event for an apparatus, said system comprising:

means for monitoring stress waves generated by the apparatus during operation of the apparatus;

means for processing said stress waves to generate derived values;

means for comparing said derived values to a threshold value; and

means for generating an impending stall signal based on an output of said means for comparing.

16. The system of claim 15, wherein said means for monitoring stress waves includes a plurality of sensors mounted on the apparatus.

17. The system of claim 16, wherein said sensors have a resonance response between 20 kHz and 100 kHz.

18. The system of claim 15, wherein said means for monitoring stress waves includes:

a first sensor mounted on the apparatus at a first location to detect a first series of stress waves, and

a second sensor mounted on the apparatus at a second location to detect a second set of stress waves; and

wherein

said means for processing said stress waves to generate derived values includes;

means for processing said first series of stress waves to generate a first series of stress wave energy values,

means for processing said second series of stress waves to generate a second series of stress wave energy values, and

means for calculating a difference between said first series of stress wave energy values and said second series of stress wave energy values to generate said derived values.

19. The system of claim 18, wherein said sensors have a resonance response between 20 kHz and 100 kHz.

20. A system for predicting an impending stall event for an apparatus, said system comprising:

means for monitoring a first part of the apparatus to detect a first series of stress waves;

means for monitoring a second part of the apparatus to detect a second series of stress waves;

means for processing said first series of stress waves to generate a first series of stress wave energy values;

means for processing said second series of stress waves to generate a second series of stress wave energy values;

means for calculating a difference between said first series of stress wave energy values and said second series of stress wave energy values to generate energy difference values;

means for comparing said energy difference values to a threshold value;

means for comparing said first series of stress wave energy values to a normal operating value; and

means for generating an impending stall signal when both of;

said difference values cross said first threshold value, and said first series of stress wave energy values are near said normal operating values.

21. The system of claim 20, wherein said means for monitoring the first part of the apparatus is a first sensor mounted in or on the apparatus at a first location, and wherein said means for monitoring the second part of the apparatus is a second sensor mounted in or on the apparatus at a second location.

22. The system of claim 21, wherein each of said means for processing said first series of stress waves and said means for processing said second series of stress waves includes a filter for filtering noise and a demodulator for detecting amplitude modulations of the stress waves series for generating a first stress wave pulse train and a second stress wave pulse train.

23. The system of claim 22, wherein a CPU is used for generating said first series of stress wave energy values from said first stress wave pulse train and for generating said second series of stress wave energy values from said second stress wave pulse train.

24. The system of claim 23, wherein said CPU includes said means for comparing said energy difference values to a threshold value and said means for comparing said first series of stress wave energy values to a normal operating value.

25. The system of claim 24, wherein said CPU also includes said means for generating an impending stall signal.

26. The system of claim 24, wherein said CPU is located remotely from the apparatus.

27. A system for predicting an impending stall event for an apparatus, said system comprising:

a first sensor provided at a first location on the apparatus for monitoring a first series of stress waves for generating a first sensor output signal;

a second sensor provided at a second location on the apparatus for monitoring a second series of stress waves for generating a second sensor output signal;

a first electric assembly for receiving said first series of stress waves, said first electric assembly including a filter for filtering said first sensor output signal and also including a demodulator for demodulating said first sensor output signal to output a first pulse train;

a second electric assembly for receiving said second series of stress waves, said second electric assembly including a filter for filtering said second sensor output signal and also including a demodulator for demodulating said second sensor output signal to output a second pulse train;

a processor adapted for processing said first pulse train into a first series of stress wave energy values, said processor also adapted for processing said second pulse train into a second series of stress wave energy values, wherein said processor utilizes said first series of stress wave energy values and said second series of stress wave energy values to generate derived values for comparing to a threshold value, said processor also adapted for determining whether said first series of stress wave energy values represent a normal operating condition, wherein

said processor is adapted for generating an impending stall signal based on results of said comparing and said determining.

28. The system of claim 27, wherein said processor is adapted such that said derived values are based on a difference between said first series of stress wave energy values and said second series of stress wave energy values, and wherein said processor is adapted for generating said impending stall signal when both said derived values cross said threshold and said determining results in a determination that the operating condition is not abnormal.

29. The system of claim 28, wherein said impending stall signal is used by said system for generating an impending stall notification to an operator of the apparatus.

30. The system of claim 27, wherein said sensors have a resonance response between 20 kHz and 100 kHz.