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For the pump-stopping water hammer prevention of the floating pumping station water-conveying system, in addition to ensuring the safety of the pump unit and the pipeline, the impact of the water hammer pressure on the movable rocker pipe and the floating boat should be considered to ensure the stability of the floating boat. The numerical simulation of the pump-stopping transient of a floating pumping station water-conveying system under large range variable water source level was conducted. The results show that the lowest inlet water level is the most unfavorable condition for water hammer prevention. Under the condition that the pump outlet valve refuses to close, if the unit’s reverse speed exceeds the standard and the maximum reverse flow is reached within 3 s after the pump-stopping. The axial-flow check valve is recommended for the pump outlet valve considering the valve driving capacity requirements, the unit reverse speed and water hammer pressure. In the water hammer protection scheme of "pump outlet axial-flow check valve + air chamber on shore + intermediate check valve + hammer-prevention air valve", the axial-flow check valve ensures that the pump unit does not reverse, the air chamber and air valve reduce the maximum water hammer pressure and improve the negative pressure condition in the pipeline, and the intermediate check valve reduces the pressure oscillation amplitude and oscillation time in the pump outlet and rocker pipe. Therefore, the water hammer prevention problem in the floating pumping station water-conveying system is effectively solved.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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