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In the hydraulic transition calculation of long-distance water transmission pipeline, the intake and exhaust coefficient of air valve is mostly constant. In order to explore the influence of the intake and exhaust coefficient of water hammer air valve on the change of pipeline pressure, the DN100 water hammer air valve was simulated by FLUENT software to obtain the mass flow at -9 kPa -11 kPa, and the dynamic intake and exhaust coefficient curves with different pressure differences were established. Taking Xishan primary water lift pump station as an example, dynamic value and fixed value were adopted for air valve inlet and exhaust coefficient respectively (mean value 0.55) to calculate and compare the transition process. The numerical simulation results show that the improved dynamic inlet and exhaust coefficient of the air valve has little impact on the negative pressure of the pipeline and great impact on the positive pressure. The improved dynamic inlet and exhaust coefficient effectively reduces the pressure fluctuation in the pipeline. In the actual operation of the pump station, it is necessary to pay attention to the positive pressure change of the pipeline, and strengthen protection. The calculation of water hammer prevention should be based on the measured data of air valve inlet and exhaust. The research results can provide some references for the hydraulic transition calculation of air valve in the operation of pump station.
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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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