高焓条件下燃料点火延迟调节对超燃发动机燃烧性能的影响

为了研究燃料与空气化学反应活性变化对超燃冲压发动机燃烧性能的调节机制,本文以氢燃料为基础,基于阿伦尼乌斯反应动力学体系和不确定量化分析(Uncertainty Quantification,UQ)方法,构建点火延迟可调的燃料模型,通过一系列的数值计算,对比分析燃料在不同点火延迟特性下的超声速燃烧特性。计算结果表明：基于不确定量化分析方法能够合理地构建基于点火延迟时间的氢燃料特性变化模型；当前高焓来流环境下,随着燃料点火延迟的增加,燃烧效率并不简单的单调递减,以氢气的基准点火延迟为参照,燃烧效率随点火延迟的变化存在两个清晰的拐点,并以此构成三个不同的特征区域,说明燃料的点火延迟特性对燃烧性能起不同程度的调控作用,详细的流动机理有赖于进一步针对燃烧流动结构形成和演化过程的精细化研究。

The role of fuel ignition delay time on supersonic combustion performance at high stagnation temperature

In order to study the influence of fuel characteristics on the combustion performance of scramjet engine, a hydrogen-based fuel was used to construct a hydrogen fuel model with adjustable ignition delay time based on the method of uncertain quantitative analysis. Numerical calculations were carried out by RANS method. Based on ignition delay time, combustion chamber wall pressure distribution, total pressure loss, combustion efficiency and thrust, the supersonic combustion characteristics of hydrogen fuel under different characteristics were compared and analyzed. The calculation results show that the characteristics changing model of hydrogen fuel based on ignition delay time can be reasonably constructed based on the uncertain quantitative analysis method. Under the current inflow environment, the combustion efficiency is not simply monotonically decreasing with the increase of fuel ignition delay time. The combustion efficiency curve has two clear inflection points with the change of ignition delay time, and constitutes three different characteristic regions. The characteristics of fuel has different degrees of regulation mechanism on combustion performance, however, the detailed mechanism needs further research on the formation and evolution of combustion flow structures.