

1 1 



LARGE BULB 



SMALL BULB 



- 



I 

 1 



•^ 



— 



1 1 

 1 1 



\ 



2.7 



' 



n 



1 1 



0.229 0.241 



3/4 SPAN 



0.254 0.267 



SPAN (ml 



Figure 7 - Photograph and Spanwise Thickness Distribution for 

 the Small and Large Bulbous Tips 



limited to the area 0.5 in. (0.013 m) inboard from the tip, corresponding to an 

 area of approximately 0.7 percent of the total pressure side area; for the suction 

 side, application was limited to the area 0.25 in. (0.006 m) inboard from the tip, 

 representing an area of approximately one-half of that treated on the pressure side. 

 These optimum areas of application were determined from paint flow studies and will 

 be discussed later. The following roughness configurations were evaluated: pressure 

 side only, suction side only and both pressure and suction sides. A range of rough- 

 ness heights was obtained by using percision grain size silicon carbide, 90-800 

 microns, which was applied with two-stage epoxy resin and easily removed with appro- 

 priate epoxy stripper. Figure 8 is a photograph showing an overall and closeup view 

 of 600 micron roughness applied to the parent foil pressure side. 



Mass Injection 



For the passive mass injection foil, a channel was fabricated through the tip 

 connecting the foil pressure and suction sides and aligned with the free stream flow. 



12 



