| Abstrakt: |
A theory is developed that is shown to give good prediction of the headdischarge relationships for two designs of vortex drop structures. The first design is the widely used spiral guide wall design, and it is shown that control is shared between the critical section at the top of the shaft and the vortex inducing asymmetry of the guide wall inlet design. A second simplified and more space saving design, called the vertical slot vortex drop structure, is also analyzed. It is shown that, although the flow conditions and analysis are quite different, the resulting headdischarge relationship is quite similar to the spiral guide wall design. For both designs the headdischarge relationship is shown to be almost linear and the theoretical and measured discharges are in close agreement. The proposed vertical slot design produces a stable air core, similar to the spiral guide wall design, and consequently the flow is free from risk of surging to the pipefull flow condition. The compactness of the new design is especially suitable for underground installations. |
