Based on the computational fluid dynamics software CONVERGE, a numerical simulation of the methanol spray auto-ignition process was carried out using the large eddy simulation method. The effect of ambient oxygen volume fraction on auto-ignition characteristics of the methanol spray was studied in a constant volume combustion bomb at an ambient temperature of 1200K and an ambient pressure of 7.77MPa. The results show that when the ambient oxygen volume fraction decreases from 21% to 15%, the ignition delay time(IDT) increases by 2.5%. When the ambient oxygen volume fraction further decreases to 10%, the IDT increases by 8.1%. At 10% ambient oxygen volume fraction, a tiny amount of OH is generated during methanol combustion and always distributed in the periphery of methanol spray. From the perspective of the spatiotemporal distribution characteristics of CH2O, as the oxygen volume fraction decreases, the temperature range of CH2O generation narrows, the equivalence ratio range widens, and the spatial distribution range of CH2O increases and the concentration distribution becomes more uniform. It can be seen that the change of ambient oxygen volume fraction significantly affects the ignition characteristics of methanol spray, and then affects the generation and distribution of its key radicals (CH2O, OH).
| 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 |