518 



Discussion 



R. LATORRE 



Our lack of understanding of cavitation noise 

 and its measurement technique is an area of recent 

 concern and the authors' experiments and discussion 

 will hopefully aid other researchers with these 

 problems . 



The correlation of cavitation noise and the 

 observed cavitation is a complicated research topic. 

 In my dissertation I am studying tip vortex cav- 

 itation noise and as a contribution to the authors' 

 paper, I would like to present some illustrative 



^ 



/B 



m. TOKYO CAVITATION TUNNEL 



FIGURE 1. 

 ment. 



Tip vortex cavitation noise measure- 



SHIP RESEARCH INSTITUTE 

 CAVITATION TUNNEL 



KEY: 



FOIL / PROPELLER 



TIP VORTEX CAVITATION 



B & K 8103 HYDROPHONE 



B & K 2625 COND. AMP, 



RION 1/3 BAND PASS FILTER 



RION HIGH SPEED LEVEL 

 RECORDER 



B) 



10 



I I I I I I I I I I I I I I 



SRI HEASUREMENT 

 PROPELLER No. 121 

 Q |_J = .35, N = 20 RPS 

 ■" 1 - 0^ = 23.06 

 2 - S^ = 20.0 3 - e„ = 19. 

 Ill 



0,5 1 2 5 10 KHz 

 1/3 OCTAVE BAND CENTER FREQUENCY 



20 



I I I I II II I I II I I 



SRI heasurehenI 



lA SRI FOIL, 6.5 H/S, 10" 



1 - 0^ = 2.3 tJ/n = ''19 ■ 

 2-0^ = 2.3 

 3 - <3„ = 2.0 

 M I I I I I 



0.5 1 2 5 10 KHz 



1/3 OCTAVE BAND CENTER FREQUENCY 



FIGURE 2. Tip vortex cavitation noise measure- 

 ments of propeller and foil tests comparison of 

 intermittent and steady tip vortex cavitation 

 noise. 



HO 



20 



D) 3.15 KHz BAND CENTER FREQ. 



UNIV. TOKYO TEST 

 l/'l SRI FOIL 



12 M/S, 10- 



1 - d, = 3,5 

 2 - 8^ = 2.8, 3 - 6.^ = 2.7 

 I I I I I M I I I I I I I 



0.5 1 2 5 10 KHz 

 1/3 OCTAVE BAND CENTER FREQUENCY 



10 (JB 



1 INTERMITTENT = 2 STEADY = 3 

 TIP VORTEX CAVITATION TEST (REF, C) 



DEVELOPMENT OF TIP VORTEX CAVITATION NOISE 

 TRACE OF NOISE SIGNAL AND NOISE ENVELOPE 



