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Water-jet pumps are widely used in power fields such as ships, and the internal cavitation flow characteristics have an important impact on propulsion performance. In order to quantitatively evaluate the energy loss in cavitation flow field, the cavitation characteristics of an axial water-jet pump were studied based on entropy production theory. As the tip clearance vortex cavitation is typical in axial-flow propulsion pumps, the local vortical flow features were considered in the present numerical method. The SST-CC turbulence model with rotation correction and a modified cavitation model based on vortex identification were adopted. The numerical calculation method was verified according to the referenced experiment of a model pump. The results show that, under different cavitation conditions, with the deterioration of cavitation, the increase of entropy production value reflects the increase of energy loss of water-jet pump, which is corresponding to the decrease of efficiency curve, and the change law of total entropy production in pump is basically consistent with its power characteristics. Analysis of the energy loss in each geometrical region of the water-jet pump shows that the entropy production in the impeller section is the highest, especially the turbulent dissipation and wall dissipation, which are closely related to the vortex and cavitation flow field in the tip clearance of the impeller. On the different cavitation conditions, study on the flow characteristics at the tip of the impeller shows that the tip leakage vortex region causes cavitation, but significant energy dissipation occurs at the outer edge of leakage vortex and on the nearby wall area, while the cavitating vortex attached on the blade surface is the main source of turbulent dissipation.
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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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