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Preliminary Test Results for the Modified* Philtec D63 Optical Probe for use as a High

Speed Time of Arrival (TOA) Probe

John J Jagodnik

Project EngineerMechanical Solutions, Inc.11 Apollo DriveWhippany, NJ 07981(973) 326-9920 x123jjj@mechsol.com

4/16/2009

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MSI’s Compressor Test Rig

• MSI tested the 2 MHz bandwidth D63 optical probe on our in house high speed compressor test rig.

• The compressor test rig uses a small axial blisk from a 2 stage LTS101 Turboshaft Engine.

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MSI’s Compressor Test Rig

• MSI’s compressor test rig includes:

• A shaker to excite blade modes

• Instrumented shroud

• Telemetry to simultaneously monitor strain on 2 blades

• A variable speed electric motor

Shaker

Shroud Telemetry Variable Speed

Motor

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MSI’s Compressor Test Rig

• The Philtec D63 Probe was attached to the shroud and pointed radially inward at the blade tips.

• The time of arrival (TOA) of each blade was recorded using an 80 MHz NI counter timer card.

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Vibrating Blade Test Results

1500 RPM Blades 1 and 10 Vibrating

0.00E+00

5.00E-07

1.00E-06

1.50E-06

2.00E-06

2.50E-06

3.00E-06

3.50E-06

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Blade Number

ST

DE

V o

f ex

pec

ted

Arr

ival

Tim

e (s

ec)

• While spinning at 1500 RPM, the shaker was activated at the first bending frequency of Blade 10.

• This resulted in higher non-synchronous vibration levels on Blade 10 (Blade 1 also demonstrated higher vibration levels).

• All other blades (which have higher first bending frequencies) vibrated at significantly lower levels.

• A larger standard deviation of the expected arrival time was observed for the vibrating blades.

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Non Vibrating Blade Test Results

2000 RPM No Vibration

0.00E+00

5.00E-07

1.00E-06

1.50E-06

2.00E-06

2.50E-06

3.00E-06

3.50E-06

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Blade Number

ST

DE

V o

f E

xpec

ted

Arr

ival

Tim

e (s

ec)

• A test was then conducted spinning at 2000 RPM with no shaker excitation.

• This resulted in low vibration levels for each blade.

• No variations in the standard deviation of the expected arrival time were observed, indicating that no blades were significantly vibrating.

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Deviation from the Expected Arrival Time vs. Rotation Number

• The blade vibration can be detected directly from the deviation in expected arrival time curves for each blade.

• The graph on the left demonstrates that for rotations 10-50, Blade 2 (low vibration levels) has only small deviations from the 24 Blade average deviation (representative of average rotational speed fluctuation).

• The graph on the right demonstrates that for rotations 10-50, Blade 10 (high vibration levels) has large deviations from the 24 Blade average deviation.

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Future Work

• MSI has ordered two D63 optical probes with modified amplifiers for higher slew rates.

• One probe will be used as a once per rev, monitoring a shaft keyway near the blades.

• The second probe will monitor blade time of arrival.

• The combined 2 probe method will be used to separate out arrival time variations caused by fluctuations in shaft rotational speed.