ElectroScience Laboratory 1 EM PROPAGATION IN JET ENGINE TURBINES Eric Walton, Jonathan Young, Jim Moore and Kyle Davis The Ohio State University ElectroScience Laboratory 2006 AMTA Meeting; Austin TX.

ElectroScience Laboratory 2 EM PROPAGATION IN JET ENGINE TURBINES

ElectroScience Laboratory 3 EM PROPAGATION IN JET ENGINE TURBINES 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)

ElectroScience Laboratory 4 A-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)

ElectroScience Laboratory 5 EM PROPAGATION IN JET ENGINE TURBINES 747 Turbine (inlet to stage 1 borehole) TIME (NS) Free space Noise level NO INITIAL IMPULSE

ElectroScience Laboratory 6 EM PROPAGATION IN JET ENGINE TURBINES Amp. (dB) vs. Freq.; F110 Outlet to Inlet; Circumf. Polarization; Various Blade Rotation Angles Free space window CIRCUMFERENTIAL

ElectroScience Laboratory 7 EM PROPAGATION IN JET ENGINE TURBINES Amp. (dB) vs. Freq.; F110 Outlet to Inlet Radial Polarization; Various Blade Rotation Angles window RADIAL

ElectroScience Laboratory 8 EM PROPAGATION IN JET ENGINE TURBINES Amp. (dB) vs. Time (ns); F110; Outlet To Inlet Radial Polarization; Various Blade Rotation Angles Ring Down = 20 ns RADIAL (CIRC. SIMILAR)

ElectroScience Laboratory 9 EM PROPAGATION IN JET ENGINE TURBINES 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 ANGULAR SETS CALIBRATION TO FREE SPACE PROPAGATION (SAME DISTANCE)

ElectroScience Laboratory 10 EM PROPAGATION IN JET ENGINE TURBINES 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.

ElectroScience Laboratory 11 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

ElectroScience Laboratory 12 EM PROPAGATION IN JET ENGINE TURBINES No variation with rotation! F-16

ElectroScience Laboratory 13 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 Tx Rx

ElectroScience Laboratory 14 EM PROPAGATION IN JET ENGINE TURBINES CONSIDER A SINGLE DOMINANT SCATTER (THIS SHOULD PRODUCE A SINGLE MODE INTERFERENCE PATTERN) one direct path and one main scatter As Zs Rs Ts Ar Zr Rr Tr DATA FILE “Direct_one.txt” SINGLE MODE PATTERN (NOTE PERIODICITY IS AS EXPECTED) WE EXPECT THIS BEHAVIOR ! AMP (DB) 2.0FREQ (GHZ)20.0

ElectroScience Laboratory 15 EM PROPAGATION IN JET ENGINE TURBINES NOW LETS GET MORE COMPLEX: NOTE MULTIPLE BLADES/SCATTERERS PER STATOR/ROTOR DISK PARTIAL F16 GEOMETRY WITH FLOOR BOUNCE INCLUDED (SORT OF) Tx Rx

ElectroScience Laboratory 16 EM PROPAGATION IN JET ENGINE TURBINES SUPPOSE WE PUT THE TURBINE INTO ROTATION: STATOR SCATTERER ROTOR SCATTERER RECEIVER ON ROTOR SIMPLE CASE AS SHOWN BEFORE

ElectroScience Laboratory 17 EM PROPAGATION IN JET ENGINE TURBINES SET OF FREQUENCY SCANS FOR ROTATING TURBINE (SIMPLE SCATTERER CASE) BASICALLY, THE PHASE OF THE SCATTERER VARIES WITH THE ROTATION AS EXPECTED 2 GHZFREQ.20 GHZ TRANSMISSION (DB)

ElectroScience Laboratory 18 EM PROPAGATION IN JET ENGINE TURBINES Example Results from the Model Data for Various Blade Rotation Angles (1-way prop.; 20 stators, 20 rotors). 2 GHZFREQ.20 GHZ TRANSMISSION (DB)

ElectroScience Laboratory 19 EM PROPAGATION IN JET ENGINE TURBINES 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

ElectroScience Laboratory 20 EM PROPAGATION IN JET ENGINE TURBINES TAKE AWAY CONCLUSION IT SHOULD BE “POSSIBLE” TO COMMUNICATE WITH SENSORS INSTALLED INSIDE A JET ENGINE TURBINE.