EXPANDING HOOD 



HOOD. LENGTH 



Figure 13. Nozzle parameters varied in hydraulic test 

 (after Rosati and Kraus 1988) 



By means of either the nozzle design or by bending the bars used to mount the 

 nozzle to the rack, the entrance to each nozzle was positioned upstream from 

 the rack to minimize flow disturbance caused by the mounts and rack. A 

 prototype streamer trap rack as used in the field was employed to position 

 nozzles at a particular elevation for hydraulic testing; the 0.4-m-long rack 

 legs were removed because they served no purpose on the metal floor of the 

 tank. Tape was used to attach nozzles to the rack. 



Test Conditions 



Definition of terms 



37. Hydraulic efficiency Ej, is defined as the ratio of the average 

 flow speed directly in front of the sampler nozzle V t (units of distance per 

 time) to the average speed for the same ambient flow condition at the same 



27 



