ElectroScience Laboratory 1 EM PROPAGATION IN JET ENGINE TURBINES Eric Walton, Jonathan Young, Jim...

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ElectroScience Laboratory

EM PROPAGATIONIN JET ENGINE TURBINES

Eric Walton, Jonathan Young,

Jim Moore and Kyle DavisThe Ohio State University


2006 AMTA Meeting; Austin TX.


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EM PROPAGATION IN JET ENGINE TURBINES


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Small Turbine(F16)

(compressor stage only)

Large Turbine[“F-110-GE-100”]

(747)

Borehole locations

“B” = INLET TO COMPRESSOR(on the bottom in this photo)“A” = OUTLET FROM COMPRESSOR(on top in photo)


4A-to-bottom borehole transmission

(circumferential polariz. 90° increments)

Circumfer’l Polarization

FROM PREVIOUS SLIDE, THERE IS ONLY 45 CM RANGE SPREAD (1.5 NS), WHILE THESE DATA ARE SHOWING APPROX. 5 NS SPREAD

F16 TURBINE

OTHER DATA SHOWS SIMILAR RIPPLE PATTERN.

FREE-SPACE (same dist)


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747 Turbine(inlet to stage 1 borehole)

TIME (NS)

Free space

Noise level

NO INITIAL IMPULSE


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Amp. (dB) vs. Freq.; F110 Outlet to Inlet; Circumf. Polarization; Various Blade Rotation Angles

Free space

window

CIRCUMFERENTIAL


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Amp. (dB) vs. Freq.; F110 Outlet to InletRadial Polarization; Various Blade Rotation Angles

window

RADIAL


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RING DOWN TIME

Amp. (dB) vs. Time (ns); F110; Outlet To InletRadial Polarization; Various Blade Rotation Angles

Ring Down = 20 ns

RADIAL (CIRC. SIMILAR)


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TEST MATRIX(I CAN’T SHOW ALL OF IT IN THE TIME ALLOTTED)

•F16 AND 707 TURBINES•RADIAL AND CIRCUMFERENTIAL POLARIZATION •2 TO 20 GHZ•A SMALL ROTATIONAL SECTOR WITH SMALL INCREMENTS•THROUGH ENTIRE COMPRESSOR SECTION•TO/BETWEEN VARIOUS BOREHOLE COMBINATIONS•0-90-180-270 ANGULAR SETS•CALIBRATION TO FREE SPACE PROPAGATION (SAME DISTANCE)


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• Signal loss is often less than in free space. (confined?)• There is no isolated initial time domain term.

•signal is spread out in time so initial direct term is as small as the multiple reflection terms.

• The multiple reflection terms spread out over a duration that corresponds to no more than 3 times the physical size of the turbine.• In the time domain

•individual stages can be discerned•but not individual turbine blades•this indicates that the internal propagation

•is axial•with multiple reflections•but not circumferential or spiral.


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EM “WINDOWS” IN JET ENGINE TURBINES

Amp. (dB) vs. Freq. and Rotation; F110-GE-100 (Boeing 747) Propagation to Farthest Borehole (Circumf. Polariz) vs. Freq. and Rotor Position.

WINDOWS

No variation with rotation!

747


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No variation with rotation!

F-16


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EM MODEL OF TURBINE PROPAGATION

MODEL THE PROPAGATION INSIDE A TURBINE AS A SIGNAL TRANSMITTER AND A SIGNAL RECEIVER WITH A SET OF “POINT” SCATTERERS IN BETWEEN.

(A “POINT SCATTERER” IS A POINT IN SPACE WHERE THE SCATTERING IS CENTERED. THE SCATTERER HAS NO FREQUENCY, ANGLE, OR POLARIZATION DEPENDENCE.)

R S R S R S R

TxRx


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-20

-10

0

10

20

-20

-10

0

10

20

0

5

10

15

20

25

30

DISTANCE (CM)

Walton Turbine Propagation Model (red rotors, green stators)

one direct path and one main scatter

2 4 6 8 10 12 14 16 18 20-25

-20

-15

-10

-5

0

5

10

FREQ one direct path and one main scatter

SIG

NA

L A

MP

LIT

UD

E (D

B)

ONE-WAY TURBINE PROPAGATION, 1 stators & 1 rotors

CONSIDER A SINGLE DOMINANT SCATTER(THIS SHOULD PRODUCE A SINGLE MODE INTERFERENCE PATTERN)

one direct path and one main scatterAs Zs Rs Ts Ar Zr Rr Tr1 0 28 0 1 34 18 0.9 25 22 30 .01 27 23 45

DATA FILE “Direct_one.txt”

SINGLE MODE PATTERN (NOTE PERIODICITY IS AS EXPECTED)

WE EXPECT THIS BEHAVIOR !

AM

P (

DB

)

2.0 FREQ (GHZ) 20.0


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NOW LETS GET MORE COMPLEX:

-40

-20

0

20

40

-40

-20

0

20

400

10

20

30

40

50

60

70

80

DISTANCE (CM)


bigger f16 Turbine model (with floor bounce)

NOTE MULTIPLE BLADES/SCATTERERS PER STATOR/ROTOR DISK

PARTIAL F16 GEOMETRY WITH FLOOR BOUNCE INCLUDED (SORT OF)

Tx

Rx


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-20

-10

0

10

20

-25 -20 -15 -10 -5 0 5 10 15 20 25

0

5

10

15

20

25

30


one direct path and one main scatterDISTANCE (CM)

SUPPOSE WE PUT THE TURBINE INTO ROTATION:

STATOR SCATTERER

ROTOR SCATTERER

RECEIVER ON ROTOR

SIMPLE CASE AS SHOWN BEFORE


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2 4 6 8 10 12 14 16 18 20-25

-20

-15

-10

-5

0

5

10

FREQ one direct path and one main scatter

SIG

NA

L A

MP

LIT

UD

E (D

B)


SET OF FREQUENCY SCANS FOR ROTATING TURBINE(SIMPLE SCATTERER CASE)

BASICALLY, THE PHASE OF THE SCATTERER VARIES WITH THE ROTATION AS EXPECTED

2 GHZ FREQ. 20 GHZ

TR

AN

SM

ISS

ION

(D

B)


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2 4 6 8 10 12 14 16 18 20-40

-30

-20

-10

0

10

20

30

FREQ bigger f16 Turbine model (with floor bounce)

SIG

NA

L A

MP

LIT

UD

E (

DB

)



Example Results from the Model Data for Various Blade Rotation Angles (1-way prop.; 20 stators, 20 rotors).

2 GHZ FREQ. 20 GHZ

TR

AN

SM

ISS

ION

(D

B)


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CONCLUSIONS

•PROPAGATION DOES NOT HAVE UNACCEPTABLY LARGE LOSSES (5 TO 30 DB COMPARED TO FREE SPACE)

•THE STATOR ANGLE EFFECTS THE PROPAGATION.

•MULTIPATH (RINGING) IN THE TIME DOMAIN IS LESS THAN THREE TIMES THE PHYSICAL SIZE OF THE TURBINE. (THUS LESS THAN 20 TO 40 NS)

•POLARIZATION EFFECTS ARE STRONG IN MOST BANDS.

•THERE ARE SOME NARROW FREQUENCY BANDS WHERE THE ROTATION ANGLE OF THE TURBINE HAS ONLY A SMALL EFFECT ON THE PROPAGATION.

DATA SET AVAILABLE TO INTERESTED PARTIES – CONTACT ERIC WALTON


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TAKE AWAY CONCLUSION

IT SHOULD BE “POSSIBLE” TO COMMUNICATE WITH SENSORS

INSTALLED INSIDE A JET ENGINE TURBINE.

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ElectroScience Laboratory 1 EM PROPAGATION IN JET ENGINE TURBINES Eric Walton, Jonathan Young, Jim...

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