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Diesel spray characteristics under hydrogen atmosphere were researched by employing backlighting techniques in a virtual high-pressure constant-volume vessel under an environmental pressure of 2MPa and an environmental temperature of 293K. The effects of hydrogen volume fraction λH and fuel injection pressure pinj on the macroscopic and microscopic characteristics of diesel spray were discussed in detail. Furthermore, based on the spray characteristics results, this study clarified the effect of micro-addition of hydrogen on diesel combustion characteristics. The results indicate that the spray penetration increases with λH, but the curves overlap when pinj≥120MPa. The spray cone angle initially decreases and then slightly increases with λH, but when pinj≥120MPa, the spray exhibits intense fluctuations, and the angle changes irregularly. Small amounts of hydrogen addition(λH≤9.0%) significantly reduce droplet size, and the sauter mean diameter(SMD) decreases by 1.45% when λH=9.0% compared to that of no hydrogen addition. Excessive hydrogen addition(λH≥25.0%) inhibits secondary atomization of the spray, resulting in an increased droplet size. Due to the vortex effect, droplet size first decreases and then increases radially at lower λH, while at higher concentrations, it increases slowly along the radial direction. Microaddition of hydrogen in the atmosphere alters the diesel ignition delay time. The ignition timing is 3.55ms after the start of injection(ASOI) when λH=1.5%, and 2.70ms when λH=3.0%. As λH increases, intensity of combustion first decreases and then increases, while the duration of large-area combustion extends, leading to a more uniform distribution of diesel ignition points.
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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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