3 1.8 



O 



1.3 

 1.2 



Re = 5 (10)6 



O 600 Ai STANDARD 

 n 600 /i 



3/4 in. STRIP PRESSURE TIP 

 1/4 in. STRIP SUCTION TIP 

 A 600 p 1/2 in. STRIP PRESSURE TIP 



90 Ai 1/4 in. STRIP SUCTION TIP 

 O 600 i" 1/2 in. STRIP PRESSURE TIP 

 SMOOTH SUCTION TIP 



1/2 in. STRIP PRESSURE TIP 

 1/4 In. STRIP SUCTION TIP 



0.32 0.36 



LIFT COEFFICIENT Cl 



0.40 



Figure 26 - Tip Vortex Cavitation Inception Speed Ratio as a Function of Lift 

 Coefficient for Increased Roughness Treated Area 

 and Reduced Suction Side Roughness Grain Size 



suction side surface cavitation characteristics. For this effort, the standard pat- 

 tern was used with 90-micron grain size on the suction side tip and 600-inicron grain 

 size on the pressure side tip. -As seen in Figure 26, this arrangement resulted in 



substantial reductions in U„/U as compared to the same distribution with 600-micron 



P P 

 on both the suction and pressure sides. Although the 90-micron/ 600-micron arrange- 

 ment improves the surface cavitation characteristics as compared to the 600-micron/ 

 600-micron arrangement (Figure 25), this grain is negated by the corresponding loss 

 in TVC performance. 



37 



