Effect of spilling from adjacent orifices on the velocity field and pressures in front of needle stop-logs

In this study, the effect of spilling from neighboring sluice gates on stop-logs was experimentally investigated on a 1:65 physical scale model comprised of a double arch dam, a reservoir area, six spillway orifices and two stop-logs. Two types of measurement were performed: 2D velocity field in approach flow zone at the central horizontal plane of the orifices using two 0.5 MHz long range UVP transducers and dynamic pressures acting on the needle stop-logs at nine relevant positions using piezo-resistive pressure transmitter. The results showed that the pressure acting on the needle stop-logs followed hydrostatic distribution and velocity magnitudes in the zone of the needle stop-log are low and mostly unaffected by the spilling of the neighboring sluice gates.