246 



gn no 270 



« 90 I 120 160 I 200 240 I 280 320 



3eo 



FIGURE A-1. Circumferential dis- 

 tribution of piezoelectric pres- 

 sure transducer signals for 15- 

 knot run 209. 



UOO 



13 90 



5-30 

 12 5 25 



5-20 



U-30 



R1 l*-2 

 K-20 



970 



96-5 



960 

 2M0 ^ 



2k 05 

 24. 00 



80 120 160 



BLADE POSIIION e IN DEGREES 



200 240 2BD 320 



36D°= 9C REVOLUTION ID 17SEC I 



380 



(345 rpm) , but with the pi tot tube in different 

 angular positions, 180° for Run 205 and 300° for 

 Run 209. Run 208 was obtained at a speed of 8.9 

 knots and a propeller speed of 245 rpm, with the 

 pitot tube at 300°. 



As can clearly be seen from the data obtained 

 during Run 209, the pressure signal from the three 

 operating pressure transducers is periodic. There 

 is an obvious periodicity at twice blade frequency 

 (eighth harmonic in shaft frequency) . A Fourier 

 series analysis of the data from the two 15-knot 

 runs showed that the second harmonic in blade 

 frequency was the dominant harmonic in all three 



signals. For Run 209, the amplitude of the eighth 

 harmonic was 3 percent and those of the other har- 

 monics were generally less than 10 percent of the 

 eighth harmonic. The only exception to this is the 

 sixteenth harmonic which is again of increased mag- 

 nitude . Although the magnitude of the harmonics 

 from Run 205 were lower than those from Run 209 the 

 saem results apply. There is not obvious periodicity 

 in the data from Run 208. However, a harmonic 

 analysis of this data shows that the twelfth har- 

 monic is dominant, although not nearly to the same 

 extent as in the cases of the high speed runs. 



<o 80 120 16D M 



320 360 



9-20 



II 96 



9C 



5 40 



5 35 

 5D 



13 35 



Rl 13 30 



13-25 



26 60 



t 26' 55 



26 50 



T I S"" I n* r~- 1 i I 1 srr 



*^ . 







120 

 POSIIION 



160 •• 



IK DEGREES 



240 

 3600 = 



ao 320 360 



ONE REVOLUTION (0 17 SEC I 



FIGURE A- 2. Circumferential dis- 

 tribution of piezoelectric pres- 

 sure transducer signals for 15- 

 knot run 205. 



