Full
Outline
To improve the performance of the adjustable jet pump，the end protrusion structure of the conventional needle head was changed to a streamlined structure with smooth circular arc connections，in order to reduce the disturbance of the needle to the working fluid.Numerical simulations were conducted for adjustable jet pumps with conventional needles and streamlined needles under different nozzle opening conditions to study the influence of needle shape on energy transfer efficiency and the internal flow field.The results show that compared with the conventional needle，the streamlined needle has a smoother flow channel inside the nozzle，which can better improve the flow conditions of the needle and nozzle，thereby facilitating jet energy transfer；The overall efficiency of the adjustable jet pump in the streamlined injection needle is improved，with an increase of about 2.5% when the nozzle opening is 50.41%，and the relative head loss of the nozzle can be reduced by 5.19%.At the same time，the streamlined injection needle can improve the pressure distribution in the nozzle. Under the conditions of nozzle opening of 50.41% and flow ratio of 0.4，it ensures a minimum negative pressure calculation value of approximately -89 kPa，avoiding that excessively low pressure and cavitation occur inside the nozzle..The research results can provide references and basis for the structural design and performance improvement of adjustable 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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