# Hydraulic Analysis of a Passive Wedge Wire Water Intake Screen for Ichthyofauna Protection
## 3 Results
### Influence of Deflectors on Inlet and Approach Velocity Distributions  
The results of the measurements shown in Figures 14-17 make it possible to analyze the effect of the deflector on the inlet and approach velocities to the cylindrical wedge wire screen intake. Figure 18 compares with each other the distributions of approach velocities along the screen section at 0 degrees away from the screen surface 0.5 cm, 2.5 cm, 5.1 cm, and 7.6 cm for the case without a deflector, with a deflector with equal openings and with a deflector with varying openings. As can be seen in Figure 18, the unevenness and maximum inlet and approach velocities were clearly higher for the screen case without a deflector installed than for the cases with deflectors with equal and differentiated openings. For smaller distances (0.5 cm and 2.5 cm), slightly smaller maximum normal velocities were measured with the deflector with varied openings than with equal openings. The relationships between the distributions of inlet and approach velocities in the absence of a deflector and also with deflectors with equal and non-uniform openings for the other measurement lines analyzed at angles of 45\({}^{\circ}\), 90\({}^{\circ}\), and 135\({}^{\circ}\) were similar to those shown in Figure 15 for the 0\({}^{\circ}\) angle. Figure 17: Distributions of normal velocities along the cylindrical screen at different angles at a distance of 7.6 cm from the screen surface with (**a**) no deflector, (**b**) deflector with uniform openings, (**c**) deflector with non-uniform openings obtained in a laboratory test in the absence of flow in the hydraulic channel. Influence of Cylindrical Wedge Wire Screen and Deflectors on Maximum Inlet and Approach Velocities and Non-Uniformity of Velocity Distribution  
One of the tasks of the cylindrical wedge wire screens and deflectors was to reduce maximum inlet and approach velocities below maximum acceptable values. Figure 19 summarizes the values of maximum inlet and approach velocities \(V_{max}\) in longitudinal sections of the screen at different distances from the screen surface and at different angles in the cross-section. As shown earlier, mounting the cylindrical wedge wire screens at the end of the suction pipe reduced the value of the maximum inlet velocity from 2.17 m/s (Figure 13) to 0.08 m/s (Figure 19). In contrast, as can be seen in Figure 19, mounting any of the deflectors caused a significant reduction in the maximum inlet and approach velocities at short distances from the screen surface (0.5 cm and 2.5 cm). This effect was clearly greater when a deflector with varying opening sizes was installed than when a deflector with equally sized openings was installed. As one moved away from the screen surface, the influence decreased, and already at a distance of 5.1 cm, it was the same regardless of the type of deflector mounted. At a distance of 7.6 cm, the measured maximum velocities were similar to each other regardless of whether the deflectors were mounted or not. Figure 18: Distributions of normal velocities along the cylindrical screen at 0\({}^{\circ}\) (above the screen) with no deflector, with deflector with uniform openings, and with deflector with non-uniform openings at a distance of (**a**) 0.5 cm; (**b**) 2.5 cm; (**c**) 5.1 cm; (**d**) 7.6 cm from the screen surface obtained in laboratory tests in the absence of flow in the hydraulic channel. The effectiveness of the analyzed deflectors mounted inside the cylindrical wedge wire screen could also be expressed by the degree of equalization of inlet and approach velocity non-uniformities. Less inhomogeneity of these velocity vectors mean smaller values of the highest inlet and approach velocities at the same intake capacities. The inlet and approach velocity non-uniformities expressed by quotients (\(V_{max}/V_{aver}\)) and (\(V_{max}/V_{min}\)) are summarized in Figures 20 and 21. As can be seen, in almost all cases, the non-uniformities were significantly lower after the installation of any of the analyzed deflectors.