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As a common safety problem in water diversion engineering, water hammer is often caused by abnormal operation of valves, So, it is necessary to conduct a comparative analysis of water hammer problems under different valve adjustment methods. The CFD technology and dynamic mesh technology were used to simulate different single and double valve adjustment modes, and analyze the fluctuation of water hammer pressure at different locations in the pipeline. The results show that when the single valve is adjusted, the first fast and then slow closing valve mode has an inhibitory effect on the water hammer within a certain range of fast shutdown; The fast closing amount is too large, which will play a worsening effect of water hammer; When the fast shutdown amount is 60%, the water hammer pressure can be effectively controlled, and the water hammer will deteriorate when the fast shutdown amount is 80%; When adjusting the double valve, considering the pressure before and between the two valves, it can be found that the “first 0.25 s off 60%, the last 0.25 s off 40%” method can avoid the occurrence of excessive pressure and negative pressure. The research result provides a design and operation scheme for the rapid shut-off process of the valve in practical engineering.
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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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