306 



;OA 20°P /nr\ l5°P /^^T^ IO^P /^"TN 5°P /^TA 0° 



^^T^ 5°Stb. ^3^ 15° St b. Ar\ 20°Stb. 

 Ta =9.75 m 

 en=0.22 



/^ 25> 



Stb. Ar\ 30°Stb. 

 Vs=22.3kn;n=105RPM 

 Po=17.1MW.Jkq=0.69 



FIGURE 8. Cavitation "Sydney-Expess . " 



in the Aminco-colorimeter . The deflection of the 

 meter for the filtered sample was adjusted on the 

 indicating scale to "0", which served as reference 

 value. Measured values of unfiltered samples are 

 shown in Figure 10; Relative Intensity is an 

 arbitrary unit. 



The first measurements, at the end of October, 

 were made with a one-hole-aperture in the beam 

 path, the following ones with a four-hole-aperture 

 due to a thereby increased intensity. 



In order to obtain a general idea of the sensi- 

 tivity of the Aminco scattered light method, 

 standard solutions were produced using the plastic 

 spheres also used for the calibration of the LSL- 

 instrument. It is apparent from this that five 

 parts per cm with a diameter of D = 25.7 pm could 

 still be measured. 



Many results from investigations of sea water 

 did not show any difference between filtered and 

 unfiltered samples. The content of suspended 

 particles was thus very small in the Indian Ocean; 

 it was below the response level of the Aminco-device . 

 The samples taken on the 7th December 1977 contained, 

 however, suspended particles. They descended from 

 the shallow water region of the Bab-el-Mandab at 

 the entrance to the Red Sea. 



The lack of knowledge about the back scattering 

 qualities of the particles appears to be a problem 

 when applying this scattered light method with the 



Aminco-colorimeter. A more expanded and intensive 

 investigations of suspended particles, for instance, 

 with coulter counter, could not be carried out within j 

 the frame of this research work. 



+ Scattered Laser Light M. 

 ©Velocity Measurements 



FIGURE 9. Positions of measurements. 



» Aminco - Colorimeter 

 T Total Air Content 



