For large hydrocarbon fuels used in internal combustion engines, different low-temperature and high-temperature chemistries are involved in the autoignition processes under different initial temperatures. As one of the simplest fuels with low-temperature chemistry, dimethyl ether (DME) is considered in this study and one-dimensional autoignitive reaction front propagation induced by temperature gradient is simulated for stoichiometric DME/air mixtures considering detailed chemistry and transport. The emphasis is placed on assessing and interpreting the influence of initial temperature on the detonation development regime. Different initial temperatures below, within and above the negative-temperature coefficient (NTC) region are considered. For each initial temperature, four typical autoignition modes are identified: supersonic autoignitive reaction front (without detonation); detonation development; transonic reaction front; and subsonic reaction front. The detonation development regimes for two fuels, DME and n-heptane, at the same initial temperature and those for the same fuel, DME, at three different initial temperatures respectively below, within and above the NTC region are obtained. Based on these results, the influence of fuel type and initial temperature on detonation development regime are discussed. It is found that the detonation development regime becomes narrower at higher initial temperature. Moreover, the influence of initial temperature on reaction front propagation speed is investigated. The reaction front propagation speed is shown to be strongly affected by different chemistries involved in low and high temperature regions. When only the high-temperature chemistry is involved, the reaction front propagation speed is shown to be less dependent on the initial temperature.

对于用于内燃机的大型烃燃料，在不同的初始温度下，不同的低温和高温化学成分会参与自燃过程。作为具有低温化学性质的最简单的燃料之一，本研究考虑了二甲醚（DME），并模拟了化学计量DME /空气混合物的温度梯度引起的一维自燃反应前沿传播，并考虑了详细的化学作用和运输过程。重点放在评估和解释初始温度对爆轰发展机制的影响上。考虑在负温度系数（NTC）区域以下，之内和之上的不同初始温度。对于每个初始温度，确定了四种典型的自燃模式：超音速自燃反应前沿（无爆轰）；爆炸发展；跨音速反应锋 和亚音速反应前沿。获得了在NTC区域内，上方和上方分别在相同初始温度下的两种燃料DME和正庚烷以及在三种不同初始温度下的相同燃料DME的爆轰发展机制。基于这些结果，讨论了燃料类型和初始温度对爆炸发展规律的影响。已经发现，在较高的初始温度下，爆炸发展范围变得更窄。此外，研究了初始温度对反应前沿传播速度的影响。结果表明，反应前沿的传播速度受低温和高温地区涉及的不同化学物质的强烈影响。