Abstract
When water is flowing from the bottom of a shell-type fixed wheel gate with a skin plate at the downstream side, the combined force is derived by the bottom pressure on leaf and by the weight of water in leaf and becomes extremely large downward force or uplift force. Because there is a huge water chamber in the gate leaf and water is filled in this chamber in closing condition and this chamber becomes vacancy when gate is fully opening. And under the operating conditions, water flows out from this chamber at the gate is opening and flows in at the gate is closing. There must be the suitable condition for the combined force between the parameters as the pressure at gate bottom, operating speed of gate, volume of chamber and both location and total area of holes for the water flows in and out. If this suitable condition is not satisfied under gate operation, the large downward force or uplift force arises. The method to derive the hydrodynamic vertical force is proposed in this paper on two types of gates such as the shell-type fixed wheel gate and the lower leaf of double leaf fixed wheel gate. And the effects of both the location and the total area of the holes, which are provided at the gate bottom leaf, are shown as the relation of hydrodynamic down pull or uplift force by numerical analyses.
