# Hydraulic Analysis of a Passive Wedge Wire Water Intake Screen for Ichthyofauna Protection
## 3 Results
### Tests of Approach Velocity into Cylindrical Wedge Wire Screen without Deflector  
In the next series of tests, the model of the wedge wire screen shown in Figures 4 and 6 was installed at the end of the water intake pipe, but without an internal deflector to  
Figure 12: An example of a convergence diagram (**a**) and velocity change diagram during the simulations (**b**). Figure 13: Distribution of velocities normal to the surface of the inlet pipe of a water intake without a screen installed depending on the distance from this surface obtained in laboratory tests in the absence of flow in the hydraulic trough (the distance between point A and points A–F marked in Figure 8). equalize the inflow velocity distribution. The capacity of the water intake pump during this series of tests was similar to that adopted during the tests of the intake without the screen, described in Section 3.1, and was 275 dm\({}^{3}\)/min (-4.6 dm\({}^{3}\)/s). Inflow and inlet velocities were measured along the length of the screen every 3 cm, at angles of 0\({}^{\circ}\), 45\({}^{\circ}\), 90\({}^{\circ}\), and 135\({}^{\circ}\) in cross-section and at distances from the screen surface equal to 0.5; 2.5; 5.1, and 7.6 cm. The locations of the measurement points in the cross-section are shown in Figure 9 (points 1-10) and in the longitudinal section in Figure 8. Figure 14 shows the distributions of the experimentally measured normal velocities with respect to the surface of the screen. In general, regardless of the adopted longitudinal section angle, the inflow velocities were highest on the water-sucking side and decreased along the section to the lowest value on the screen termination side. Only at a distance of 0 cm, that is, where the screen began was the value slightly smaller than at the 3 cm farther away point. In all cases, the inflow velocities decreased as one moved away from the screen surface. The highest value of inlet velocity, equal to 0.08 m/s, was recorded at a distance of 3 cm from the beginning of the screen on the suction side. This value was lower than the accepted maximum allowable inlet velocity value in the US standards, but more than twice as high as the value accepted for \"eel\" type fish in the Canadian guidelines. The value was also more than 20 times lower than the maximum velocity measured for the intake without a wedge wire screen installed at the end of the inlet (suction) pipe. To sum up, measured velocity values independent of the longitudinal cross-section analyzed as well as the distance from the inlet surface were significantly lower in the case of tests with the screen installed (Figure 14) than in the case of tests without the screen at the end of the inlet pipe (Figure 13). Figure 14: Distribution of normal velocities along the length of the cylindrical wedge wire screen (from 0 to 15 cm) at different distances from the surface of the screen (0.5; 2.5; 5.1; 7.6 cm) at an angle in the cross-section (**a**) 0\({}^{\circ}\), (**b**) 45\({}^{\circ}\), (**c**) 90\({}^{\circ}\), (**d**) 135\({}^{\circ}\) from the vertical with no deflector installed inside the screen obtained in laboratory tests in the absence of flow in the hydraulic channel. Tests of Approach Velocity into Cylindrical Wedge Wire Screen with the Deflector with Uniform Openings  
In another series of tests, approach velocities were measured around the wedge wire screen shown in Figures 4 and 6 and equipped internally with the deflector shown in Figure 7a with equal holes of 6.0 mm diameter. The deflector's task was to equalize the inflow and inlet velocities around the screen surface. As in the previous test series, no-flow conditions were simulated in the hydraulic plume. The low water flow was the result of water being drawn through the study screen and discharged at the beginning of the flume. The capacity of the pump sucking up water in the intake was 275 dm\({}^{3}\)/min (\(\sim\)4.6 dm\({}^{3}\)/s), similar to that in previous test series.