0.05 0.10 0.15 020 025 0.30 

 Unit Discharge q of Free Air (ft 3 /s/ft) 



0.35 



Figure 142. Effect of unit air discharge, q, and orifice 

 diameter on effectiveness of pneumatic breakwater 

 (after Straub, Bowers, and Tarapore, 1959). 



spacings of 1-foot centers were tested in the larger channel, but there 

 appeared to be no advantage to using multiple manifolds. Actually, for lower 

 discharges, the airflow was not uniform and resulted in poor efficiency (.Fig. 

 143). The spacing was varied for a two-manifold arrangement in the smaller 

 wave channel in an attempt to isolate the desired spacing of two release 

 points. Again, the performance appeared to be no better than for the one- 

 manifold system (Fig. 144). 



Width of Channel = 9.0 ft 

 Depth of Water = 45 ft 

 Wave Length = 8.0 ft 



Wave Steepness = 0.04 

 No. of Orifices per 



Manifold per foot = 5. 1 

 A One Manifold System 

 O Two Manifold System 

 O Three Manifold System 



0.05 0.10 0.15 Q20 025 0.30 



Unit Discharge q of Free Air (ft 3 /s/ft) 



0.35 



Figure 143. Effect of unit air discharge, q, and multiple mani- 

 fold systems on effectiveness of pneumatic breakwater 

 (after Straub, Bowers, and Tarapore, 1959). 



204 



