DETERMINING FAN PARAMETERS THROUGH PRESSURE MONITORING

• US 20110219741A1
• Filed: 03/15/2010
• Published: 09/15/2011
• Est. Priority Date: 03/15/2010
• Status: Active Grant

• Current Assignee: Rolls-Royce Corporation (Rolls-Royce Holdings Plc)
• Original Assignee: Rolls-Royce Corporation (Rolls-Royce Holdings Plc)
• Inventors: ERNST, JAMES, Collins, Shawn Thomas, Zizzo, Claudio
• Granted Patent: US 8,752,394 B2
• Time in Patent Office: Days
• US Class Current: 60/39.15
• CPC Class Codes: F01D 21/003 Arrangements for testing or measuring for measuring vibrations G01H
• CPC Class Codes: F02C 9/28 Regulating systems responsive to plant or ambient parameters, e.g. temperature, pressure, rotor speed F02C9/30 - F02C9/38, F02C9/44 take precedence
• CPC Class Codes: F02K 3/06 with front fan
• CPC Class Codes: F02K 3/072 with counter-rotating , e.g. fan rotors
• CPC Class Codes: F05D 2260/80 Diagnostics
• CPC Class Codes: F05D 2270/301 Pressure
• CPC Class Codes: G01P 3/263 by using fluidic impulse generators
• CPC Class Codes: G01P 3/48 by measuring frequency of generated current or voltage in general G01R23/00

Abstract

A method for determining the speed of at least one rotating fan, such as a propeller, through sensing pressure waves generated by the blades of the fan. An apparatus operable to execute the method is also disclosed. The apparatus includes a fan having a hub portion and a plurality of blades extending radially outward from the hub portion. The apparatus also includes an engine operable to rotate the fan about an axis of rotation. The apparatus also includes a sensor spaced from the fan along the axis of rotation. The sensor is positioned to sense at least one physical condition that is external of the engine and is changed by rotation of the plurality of blades. The sensor is operable to emit a signal corresponding to at least one physical condition. The apparatus also includes a processor operably engaged with the engine and the sensor. The processor is operable to receive the signal from the sensor and change the operation of the engine in response to the signal to change a speed of the fan.

Claims

1. An apparatus comprising:

a fan having a hub portion and a plurality of blades extending radially outward from said hub portion;

an engine operably to rotate said fan about an axis of rotation;

a sensor spaced from said fan along said axis of rotation and positioned to sense at least one physical condition external of said engine changed by rotation of said plurality of blades, wherein said sensor is operable to emit a signal corresponding to the at least one physical condition; and

a processor operably engaged with said engine and said sensor such that said processor is operable to receive said signal from said sensor and change the operation of said engine in response to said signal and change a speed of said fan.

2. The apparatus of claim 1 wherein said engine is further defined as a turbine engine housed in a nacelle and wherein at least part of said sensor is flush with an outer surface of said nacelle.

3. The apparatus of claim 1 wherein said sensor is further defined as operable to sense a level of ambient pressure.

4. The apparatus of claim 1 wherein said sensor is further defined as operable to sense a level of sound.

5. The apparatus of claim 1 further comprising:

a second fan spaced from said first fan and having a hub portion and a plurality of blades extending radially outward from said hub portion, wherein said engine is operably engaged with said second fan to rotate said second fan about said axis of rotation and said sensor is positioned to concurrently sense at least one physical condition external of said engine changed by rotation of said plurality of blades of said first fan and changed by rotation of said plurality of blades of said second fan.

6. A method comprising the step of:

determining the speed of at least one rotating propeller through sensing pressure waves generated by the blades of the propeller.

7. The method of claim 6 further comprising the step of:

changing the operation of the engine in real time in response to the speed derived from the sensed pressure waves.

8. The method of claim 6 further comprising the step of:

positioning a sensor upstream or downstream of the at least one propeller.

9. The method of claim 6 wherein said determining step further comprises the steps of:

sensing the pressure dynamically in the time domain; and

converting the pressure data sensed in the time domain to the frequency domain with a fast Fourier transform.

10. The method of claim 9 wherein said determining step further comprising the steps of:

associating the frequency having the highest magnitude in the frequency domain with the angular velocity of the propeller;

11. The method of claim 10 wherein said associating step further comprises the step of:

dividing the frequency having the highest magnitude in the frequency domain by the number of blades of the at least one propeller to determine the angular velocity of the propeller.

12. The method of claim 6 further comprising the steps of:

sensing the variation in ambient pressure dynamically with a sensor; and

ascertaining a pitch of the blades from the sensed variation in ambient pressure over time.

13. The method of claim 12 wherein said ascertaining step further comprises the steps of:

directing a signal from the sensor to a processor wherein the signal corresponds to the sensed variation in ambient pressure over time; and

filtering substantially all noise from the signal.

14. The method of claim 12 wherein said ascertaining step further comprises the step of:

assessing at least one of an amplitude and a raise+decay time of a portion of the sensed variation in ambient pressure over time.

15. The method of claim 12 wherein said assessing step further comprises the step of:

comparing the sensed variation in ambient pressure over time with a predetermined wave form.

16. The method of claim 6 further comprising the steps of:

sensing the ambient pressure dynamically with a sensor; and

identifying vibration in the blades of the at least one propeller through said sensing step.

17. The method of claim 16 wherein said identifying step further comprises the steps of:

converting the sensed variation in ambient pressure over time to the frequency domain with a fast Fourier transform; and

detecting a sequential series of frequencies in the converted ambient pressure data wherein the sequential series of frequencies has substantially the same magnitude in the frequency domain.

18. The method of claim 6 further comprising the steps of:

sensing the variation in ambient pressure dynamically with a sensor; and

identifying unbalance in the at least one propeller through said sensing step.

19. The method of claim 18 wherein said identifying step further comprises the steps of:

converting the sensed variation in ambient pressure over time to the frequency domain with a fast Fourier transform; and

detecting at least two different magnitudes having substantially the same frequency in the frequency domain.

20. The method of claim 6 wherein said determining step further comprises the steps of:

sensing the pressure dynamically in the time domain; and

converting the pressure data sensed in the time domain to the speed of at least one rotating propeller through a variable threshold comparator.

21. The method of claim 20 wherein said converting step includes the steps of:

applying a first threshold comparator over a predetermined time to identify a first number of pressure pulses having greater than a first predetermined magnitude; and

applying a second threshold comparator over the predetermined time to identify a second number of pressure pulses having greater than a second predetermined magnitude less than the first predetermined magnitude.

22. The method of claim 20 further comprising the step of:

tuning a track order filter to obtain an amplitude of pressure pulses in the time domain.

23. The method of claim 6 wherein said determining step further comprises the steps of:

sensing the pressure dynamically in the time domain; and

detecting ice on the at least one propeller from the sensed pressure data.

24. An aircraft propulsion apparatus comprising:

a turbine engine extending along a centerline axis;

a nacelle housing said turbine engine;

a first propeller driven in rotation in a first direction by said turbine engine and having a first hub portion and a first plurality of blades extending radially outward from said first hub portion;

a second propeller driven in rotation in a second direction opposite the first direction by said turbine engine and having a second hub portion and a second plurality of blades extending radially outward from said second hub portion; and

a sensor positioned to sense physical conditions outside of said nacelle changed as a result of the rotation of said first propeller and as a result of the rotation said second propeller.