Full
Outline
In response to the insufficient research on existing stratified injection nozzles regarding the “large diameter+strong throttling” structure，as well as the complexity of multi‑component injection conditions involving CO2，N2，and CH4 and the unclear flow characteristics of the nozzles，this study proposes applying the Helmholtz nozzle to stratified injection.A real gas flow model considering the variation of multi‑component fluid properties with temperature and pressure was established.The flow characteristics and influencing laws of the nozzle under different component concentrations，nozzle contraction section diameters，and confining pressures were investigated.The results show that under the same volumetric flow rate，the throttling pressure drop of the Helmholtz nozzle significantly decreases with a reduction in CO2 mass fraction.Compared to the pure CO2 control group，when the mass ratio of CO2，N2，and CH4 is 0.34∶0.42∶0.24，the throttling pressure drop reduction can reach 69.56%.The jet temperature is significantly affected by the CO2 mass fraction.Compared to the pure CO2 control group，when the mass ratio of CO2，N2，and CH4 is 0.65∶0.25∶0.10，the temperature drop increase can reach 40.56%.Under high confining pressure conditions，a high throttling pressure drop and a smaller temperature drop can be achieved.The relationship between the throttling pressure drop and the nozzle contraction section diameter exhibits an inflection point.Under specific nozzle diameter combinations，a multi‑stage throttling effect can be achieved，enabling adaptive transfer and adjustment of the throttling effect while maintaining high flow capacity.Therefore，the feasibility of using the Helmholtz nozzle as a stratified injection nozzle is high.The research findings can provide a theoretical basis for the structural design of downhole stratified injection tools and the optimization of gas injection process parameters.
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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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