220 



ZTrf- 



Ui 



■ P.on" 



■9.^ \ 



\ 



\ 



f I .; 



180° 



Vry/U 

 I — L_l_w 

 0.3 



FIGURE 29. Tangential velocity vector due to induced 

 flow on propeller disk (M-7) . 



72°) are shown in Figure 32. According to the 

 results, main effects of the stern vortices flow 

 appeared on the vertical force (F ) and the 

 horizontal bending moment (M ) of the propeller, 

 but the other components are almost negligible. 



It can be concluded that the effect of the stern 

 vortices is fairly limited to a few components of 

 forces and moments generated by propeller. The 

 results may be attributed to the tangential flow 

 around the propeller caused by the stern vortices. 

 It is mainly concentrated at the underside near the 

 bossing, and does not severely appear on the 

 propeller tip as shown in Figure 29. 



5. CONCLUSION 



The authors developed the rotor- type vortexmeter , 

 giving careful attention to the calibration method 

 of the vortexmeter, and, by using it in these tests, 

 showed its high utility. 



0.070 

 ^ 060 



Q 



^ 050 

 t- 



0-040 



0.0070r 

 ^ 00060 



■^ 00050 



o 



"^ 0.0040 



Top Starboard side 



Bottom 



90 



ISO 270 



8 (deg ) 



with stern vortices 

 without stern 

 vortices 



FIGURE 31. Variations of thrust and torque 

 coefficients on one blade (M-7) . 



Top 

 360 



0.26 



0.25 



0005 



-0005 



-0.10 



005 



— with stern vortices 



— without stern vortices 



Q029 



Thrust 



li 028 



0027 



Vertical force 



Horizontol bending Mt 



Horizontal force 



Vertical bending Mt 



,X 



-0 005 



005, 



FIGURE 30. Definitions of forces and moments due to 

 propeller. 



FIGURE 32. Variations of force and moment coeffi- 

 cients on propeller {M-7) . 



