attachment point of the tip vortex (Figure 15) and aligned streamwise with the 



vortex core. The designed AMI delivery rates were based upon tip vortex mass 



14 

 injection data obtained in wind tunnel experiments. The data from these experi- 

 ments indicated optimum injection velocities U. for vortex wake dissipation to be 

 approximately three times that of the free stream velocity 3U. For this study, with 

 U ~ 43 ft/sec (13.1 m/sec) and an injection tube ID = 0.104 in. (0.0034 m) , the 

 maximum AMI designed delivery rate was 3.42 gal/min (12.95 £/min) . 



The AMI had no measurable effect on the foil lift over the range of delivery 

 rates Q investigated — 0.3 to 2.4 gal/min (1.14-9.08 £/min) . For the higher delivery 

 rates, the foil drag was decreased approximately 10 percent as expected, due to the 

 AMI jet reaction force. 



The cavitation characteristics of the AMI are given in Figure 33. These data 

 show the following trends: 



(a) . Each of the AMI delivery rates shows significant increases in the TVC in- 

 ception speed Uq/U over the entire range of C investigated; e.g., for design C 

 ~ 0.2, a Q ~ 1.2 gal/min (4.54 il/min) resulted in a 53 percent increase in TVC incep- 

 tion speed. 



(b) . In general, U„/U increases with increasing Q up to Q ~ 1.2 gal/min (4.54 



£/min) , where further increases in Q — up to Q ~ 2.4 gal/min (9.08 £/min) — show no 



appreciable increase in U„/U . 



3 P 



(c). For the lower Q, Q ~ 0.3 and 0.6 gal/min (1.14 and 2.27 £/min) , U /U de- 

 creases rapidly with increasing C . As was the case for the roughness, apparently 

 the lower injection rates are not sufficient to dissipate or destablize the tip 

 vortex core energy for the higher tip vortex vorticity — higher C . The higher Q — Q 

 ~ 0.9, 1.2, and 2.4 gal/min (3.41, 4.54, and 9.08 il/min)— did not suffer in this 

 respect and, in general, were equally effective over the whole range of C 

 investigated. 



(d). The AMI data (Figure 33) can be used to estimate the mass delivery rates 

 produced by the PMI (Figure 32). Comparing Figures 32 and 33 over the range of pa- 

 rameters 1.2 < U„/U < 1.3 and 0.24 < C, < 0.36, one sees that the PMI 2 produced 

 P P L 



mass flow rates into the tip vortex core of from approximately 0.3 to 0.9 gal/min 

 (1.14 to 3.41 il/min). 



Based upon these observations, the optimum AMI mass flow rate is seen to be Q ~ 1.2 

 gal/min (4.54 £,/min) . It is interesting to note that this mass flow rate is 



46 



