Page - 836 - in Book of Full Papers - Symposium Hydro Engineering

The following parameters were measured: - Qa,o: To measure the air flow velocity Ua,o in the air vent, vane anemometers were mounted at two locations in the center of the air vent cross section. Qa,o was calculated assuming that the measured velocity Ua,o corresponds to 110% of the mean air velocity in the air vent. - pa: Absolute pressure sensors were installed in both gate chambers, in the middle of both tunnels and at the tunnel conjunction. - Air velocity at the end of the outlet tunnel Ua,u: Bidirectional vane anemometers were installed in the upper half of the tunnel cross section at the end of both tunnels to measure air flowing out of or into the BO tunnel. - Air temperature Ta: Temperature sensors were installed at two locations in the air vent; in the horizontal part and at the end of the air vent in the new BO. Additionally, video cameras were installed in both gate chambers and at the tunnel conjunction. Table 1 Overview on measurement devices and accuracy, symbols refer to Fig. 3 Symbol Type Name Range Accuracy U1, U2 unidirectional vane Höntzsch ZS25-mn120 1.4 - 120 m/s ± (1.5% of MV + 0.6 m/s) U3 - U5 bidirectional vane Höntzsch ZSR25-mn120 ‒60 - 60 m/s ± (1.5% of MV + 0.6 m/s) U6, U7 bidirectional vane Schiltknecht Air ‒40 - 40 m/s ± (1.5% of MV + 1 m/s) P1 - P5 absolute pressure sensor Keller PAA-26 W 700 - 1200 mbar ± 2.5 mbar R flow direction indicator VAW-made 0 - 360° ± 2° T1, T2 Air temperature Arthur-Grillo MTA90-P ‒30 - 40°C ± (0.25% of MV + 0.15°C) Fig. 3 Sketch of the measurement setup at Malvaglia Dam (not to scale) Esquisse de la configuration de mesure au barrage Malvaglia (pas à l'échelle) 836