详细化学反应机理对预混丙烷钝体熄火模拟影响

The prediction of aero engine flameout is a crucial problem. The nonlinear interaction of turbulence and chemical reactions increases the difficulty of prediction. The phenomenon and law of premixed propane bluff body blow-off were investigated by analyzing turbulence and combustion. The large eddy simulation was used to simulate turbulence with high accuracy. Three chemical mechanisms, JL4, Z66 and H73, were coupled by the transported probability density function to describe combustion process. JL4's reaction is the simplest of the three, leading to the larger rate of exothermic reaction, wider flame width, higher temperature gradient on both sides of the flame and more stable combustion, and is unable to simulate the blowoff state. The lower adiabatic flame temperature of H73 mechanism results in the lower simulated flame temperature, and the content of OH in the middle of the simulated recirculation zone is very high. In the blowoff state, a large amount of CO is oxidized, and excessive heat is released, which makes it impossible to simulate the flameout state. The mechanism of Z66 can simulate the normal state of flame, and the flameout state can be correctly simulated under low equivalence ratio. In this bluff body example, if the flame region where the local Da number is greater than 1 exceeds 35%, the extinction will occur.