Full
Outline
To deeply investigate the complex flow mechanisms inside a jet pump，2D visual measurement and quantitative analysis of the confined space jet flow field inside the jet pump were carried out based on a high‑precision particle image velocimetry （PIV） system.The study focused on the regulatory mechanisms of the area ratio m and the flow rate ratio q on its flow characteristics.The results indicate that the length of the potential core decreases as q decreases，and the smaller the m，the faster the shortening rate.The axial velocity accelerates first and then decays within the suction chamber，and the decay rate is negatively correlated with q.The height and width of the recirculation zone are negatively correlated with q and positively correlated with m.When m=4 and q=0.534，the dimensionless height and width of the recirculation zone are 0.26 and 0.73，respectively；when q drops to 0.04，the height increases to 0.6，while the width increases significantly to 4.37.The jet half‑width first increases with axial distance and then stabilizes，with q influencing the half‑width distribution in the midstream.The velocity distribution in the midstream and upstream exhibits a partial self‑similarity state，while the downstream displays pipe flow characteristics.The radial velocity shows an antisymmetric distribution，with the peak velocity decreasing as q decreases；the change in velocity direction affects the acceleration and deceleration of the jet.The throat inlet is the point of minimum pressure，and q has a significant influence on the magnitude of the pressure rise along the throat and diffuser.Complex flow structures such as jet boundary fluctuations，wake oscillations，and potential core intermittency appear in the transient flow field.Spanwise vortices are generated at the nozzle exit and distributed along the shear layer；a decrease in q intensifies the erosion of the vortex core region，promoting turbulent mixing and vorticity dissipation.The results of this study provide a reliable experimental basis for the optimal design of jet pumps.
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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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