f . Ambient flow speeds were measured at the same locations as in 

 step d. These point measurements defined the flow field 

 without the nozzle. 



42. Figure 15 presents a comparison of typical profiles measured in 

 Step b (without trap) and Step c (with trap) for the highest flow condition 

 (V mld equal to 74 cm/sec). In all cases, the difference between two speed 

 measurements at the same elevation was no more than 5 percent, and values of 

 the majority of point measurements with the trap in place were slightly 

 smaller than those taken without the trap in the tank. 



Calculation of hydraulic efficiency 



43. Hydraulic efficiencies were calculated from the flow speed data 

 using the point measurements and the area each measurement represented. An 

 example nozzle cross section with measurement locations is presented in Figure 

 16. Data corresponding to the point measurements are presented in Appendix B. 

 The hydraulic efficiency is calculated from these data as 



I v tjk A Yj Az k 

 Eh= (7) 



I v ojk A Yj Az k 



where 



V t j k = flow speed directly in front of trap nozzle 



Ay. = representative horizontal distance 



Az k = representative vertical distance 



V j k = flow speed at same location without the trap 



Hydraulic Test Results 



Overview 



44. One hundred and seventeen combinations of nozzle type, elevation of 

 nozzle in the water column, and flow condition were tested. Computed 

 hydraulic efficiencies for each test and average hydraulic efficiencies for 

 each nozzle are presented in Table 2. Tests were conducted with nozzles 

 positioned on the bed (BOT) , at midflow (MID), and at both positions using two 



31 



