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为了研究湍流脉动对化学反应的影响,在对冲火焰中引入了时空发展的扰动,其中H2O2扰动模拟组分脉动,拉伸率扰动在燃料和氧化剂边界温度均匀的条件下模拟速度脉动,在非均匀条件下模拟温度脉动。正庚烷自点火的计算结果显示:H2O2扰动可以缩短点火延迟时间。通过RO2同素异形化以及C2H3氧化的反应路径通量分析,发现H2O2扰动不会改变反应路径间的极限竞争关系。均匀温度边界条件下的拉伸率扰动通过恶化热量和自由基的损失抑制中温机理,延长点火所需时间。非均匀温度边界条件下的拉伸率扰动能产生附加的温度扰动,点火延迟时间随扰动频率的变化关系复杂。通过RO2同素异形化的反应路径通量分析可知,该扰动能够改变反应路径间的极限竞争关系,也能逆转点火进程。由此可以推断,在工程应用中,若湍流脉动较强,点火可能会从单级转化为多级。
In order to study the influence of turbulent pulsation on chemical reaction, the disturbance of space-time development was introduced into the hedge flame. The fluctuation of pulsation and elongation of H2O2 perturbation simulates the velocity pulsation under the uniform temperature of fuel and oxidant boundary, Conditions to simulate temperature fluctuations. Calculation of n-heptane self-ignition showed that H2O2 perturbation can shorten the ignition delay time. Through RO2 allotrope and C2H3 oxidation pathway flux analysis, it was found that H2O2 perturbation did not change the limit competition between the reaction pathways. Tensile rate perturbation under uniform temperature boundary conditions suppresses the medium-temperature mechanism by deteriorating the loss of heat and free radicals, lengthening the time required for ignition. Tensile rate perturbation under non-uniform temperature boundary conditions can generate additional temperature disturbances, and the ignition delay time is complicated with the disturbance frequency changes. Through RO2 allotrope reaction path flux analysis shows that the disturbance can change the limit competition between the reaction path, but also can reverse the ignition process. It can be inferred that, in engineering applications, if the turbulent pulsation is strong, the ignition may change from single stage to multiple stage.