不同自燃模式对压力波动形成的影响

在内燃机中，HCCI(均值混合气压燃)爆震、汽油机常规爆震、汽油机超级爆震都是由未燃混合气自燃引起的化学能突然释放，从而产生振荡燃烧，但其压升率及压力振荡幅值却截然不同。为了阐明其中机理，根据上述的带震荡的燃烧压力波变化规律，提出以实验测得的放热率为基础的“能量注入法”，建立了3种自燃模式。通过对能量方程中的热源项进行分类改变，进而对3种自燃模式进行数值模拟、对其产生的压力波动进行比较分析。模拟结果表明，不同震荡特征的燃烧压力波源于不同的自燃模式，从而导致其宏观表现的压升率以及压力波振荡幅值有极大的差异。以放热率为基础的“能量注入法”能准确、快捷地探究内燃机燃烧室中压力波的形成与传播。

Effect of different auto-ignition modes on the formation of pressure waves

In internal combustion engines, different combustion technologiescan result in different knocks, such as the conventional knock of gasoline engines, the super knock and the knock of HCCI engines.Though they are all caused by the auto-ignition of unburned mixture which leads to the oscillation burning, the rising rate and the oscillation amplitude of their pressure are totally different. In order to explore the inner mechanism working behind them, three kinds of auto-ignition modes were built up to illustrate the different phenomena of pressure oscillations under different combustion technologies. The differences of these three kinds of auto-ignition modes in engines were clarified. In the method of "Energy Injected", the heat source term of the energy equation can be changed based on the heat release rate obtained from experiments, and then a series of numerical simulations were conducted to realize these three kinds of auto-ignition modes. The numerical simulation shows that different auto-ignition modes will lead to different pressure waves, which can explain the different pressure rising rate and pressure oscillation amplitude. The method of "Energy Injection" based on the experiment measured heat release rate can accurately and rapidly identify the formation and propagation of pressure waves in the engine combustion chamber.