305 



Ik 



P5 = j)^jp; Pressure Pick-Up P3 (St.-B) 

 0.03- 



Damaged Propeller 

 Indian Ocean, i-12-1977 



FIGURE 5. Pressure fluctuations during laser-scattered- 

 light (LSD -measurement. 



I '^'pn 

 0.03- 



0.02- 



aoi- 



0- 



0.03- 



0.02- 



0.01- 



0' 



Deep Water with Low Nuclei Content 

 Test No 99: Vs = 22.4 Kn; n = 103.1 RPM 



iii 



_i_L 



llli.-.i 



Shallow Water with High Nuclei Content 

 Test No 105: Vs=22.5Kn;n = 101.7 RPM 



iii 



1 5 



Pressure Pick-Up Pi (Port) 

 Damaged Propeller, 

 Indian Ocean 



» I I I I I ■ . I I 



10 ► 15 



Harmonic Order n 



FIGURE 7. Harmonic components of pressure fluctuations. 



ing due to a thunderstorm at the entrance of the 

 Suez Channel. The cavitation of the damaged blade 

 was so strong that it existed during the total pro- 

 peller revolution. This could be seen through the 

 cavitation observation windows. Unfort:unately , no 

 photographies were made because the measuring crew 

 of Det Norske Veritas carrying out the cavitation 

 observations left the ship in Port Said. 



In the Mediterranean, however, a large number 

 (about 800) of black-white photographs of the 

 undamaged propeller were made with the equipment 

 of Det Norske Veritas with stroboscopic lighting. 

 Since pictures were always taken with two Hasselblad 

 cameras it might be possible to carry out stereo- 



jKpn 



0.03 



ao2 



001 

 

 0.03 

 00 2 

 0.01- 

 



Pressure Pick -Up P3 (St-B) 



iii 



I I I I I I ■■ I I 



Pressure Pick- Up Pi (Port ! 



iiii 



■ I I I I I ■ . I I 



1 5 



TEST NO 70 

 Damaged Propeller 

 Indian - Ocean 



10 ^ 15 



Harmonic Order n 



Vs = 21.8 Kn 

 n =101.7RPM 



FIGURE 6. Harmonic components of pressure fluctuations 

 during LSL-measurement. 



metric measurements of the cavitation layers in 

 dependence of the blade positions. As an example 

 for the cavitation extension of n = 105 rpm a 

 collection of photographs is shown in Figure 8. 

 These pictures were made with a camera with a fisheye- 

 objective. The photographed condition belongs to 

 Test No. 16. 



4. INVESTIGATION OF THE WATER QUALITY 



Measurements of Suspended Particles 



In addition to nuclei measurements, which will be 

 described later, the content of suspended particles 

 was investigated as often as possible. This was 

 necessary for two reasons: the LSL-method does 

 not allow direct differentiation between solid and 

 gaseous particles. Thus it became necessary to 

 estimate the proportion of dirt or organic particles 

 (probably contained in the water) in the measured 

 nuclei sprectra. For these investigations a 

 scattered-light instrument (nephelometer) was used; 

 the J4-7439 f luoro-colorimeter of the American Instru- 

 ment Company (Aminco) . The Aminco-scattered-light 

 instrument works on almost the same physical princi- 

 pie as the LSL instrument. Water samples of 1 cm^, 

 investigated in the Aminco-colorimeter under a 

 scattered light angle of 90° were exposed to a green 

 light (514 nm) as in the laser control volume. The 

 geographical positions where the Aminco scattered 

 light measurements were carried out (as well as all 

 the other measurements described in this report) 

 are shown in Figure 9 . 



The results of the Aminco scattered light investi- 

 gations, given in Figure 10, were obtained in the 

 following way: 



Water samples were taken from the condenser in- 

 flow of the ship's turbine during the voyage. One 

 part of this water was poured through a filter with 

 a pore size of 0.4 \im. Anotiier part was used for 

 tmfiltered samples, which previously were roughly 

 degassed by stirring and shaking. Subsequently, 

 the unfiltered and filtered samples were investigated 



