streamers (2ST). The nozzle description presented in Table 2 includes the 

 height and width of the nozzle, indicates whether the nozzle had a curved lip 

 (CL) , hood (H) , straight lip (SL), or door, and describes any special testing 

 conditions (type of streamer cloth, orientation of nozzle relative to flow 

 direction, etc.)- Photographs of the nozzles tested, referenced in Table 2, 

 are shown in Appendix C (Figures CI through C8). 



45. Hydraulic testing was conducted by initially evaluating each nozzle 

 for midrange and high-range flow conditions (V mid = 43 and 74 cm/sec). 

 Hydraulic efficiencies for these two flow conditions ranged from 0.75 for the 

 2.5- by 15-cm streamer nozzle, to 1.30 for the H-S sampler. The average 

 hydraulic efficiency for the "standard" 9- by 15-cm nozzle previously used in 

 the DUCK85 field data collection project (hereafter referred to as the DUCK85 

 nozzle) was close to optimum for these two flow conditions (E h = 0.94). Tests 

 conducted with the DUCK85 nozzle turned at 10- and 30-deg angles to the flow 

 (as might occur in the field), reducing the hydraulic efficiency slightly; but 

 values for the two initial flow speeds used in these variations were still 

 above 0.90. Comparison of three streamer mesh sizes indicated that the 0.105- 

 mm mesh diameter cloth (56.9 mesh/cm) previously used in the DUCK85 experiment 

 had a hydraulic efficiency closest to optimum. Because the 0.105-mm diameter 

 cloth was the most economical mesh size, all but two streamers used in the 

 hydraulic efficiency tests were constructed of this material. Shortening 

 streamer lengths to 36 cm resulted in only a 2 percent reduction in hydraulic 

 efficiency. 



46. From the initial evaluation using two flow conditions, four nozzles 

 were identified for further testing over additional flow speeds (V mid = 22 and 

 74 cm/sec) : two streamer trap nozzles with hydraulic efficiencies close to 

 optimum (2.5- by 15-cm nozzle with 5.1-cm hood (hereafter referred to as the 

 SUPERDUCK nozzle); and the 5.1- by 5.1-cm nozzle with 5.1-cm hood, hereafter 

 referred to as the Cube (C) nozzle); the H-S sampler for comparison; and the 

 DUCK85 nozzle. 



47. The hydraulic efficiency of the H-S sampler over the range of flow 

 conditions (E h = 1.30) confirms the study by Druffel et al . (1976) who 

 calculated an average hydraulic efficiency for the sampler equal to 1.54 for 



33 



