超声速燃烧室理想释热规律与理想几何构型的探索

In scramjet engines, burning in supersonic stream must always cause relatively higher heat addition losses. It has been always a major concern to find the ideal heat release of supersonic combustion to the smallest irreversibility, which corresponds to the performance limitation of supersonic combustion. The optimization of the heat release of supersonic combustion is a longstanding classic problem in scramjet propulsion. Many of the present efforts centered on parameterizing the heat release and then performing parameter optimizations to find the optimal solution approximately. Inevitably, the parameterization will introduce high-dimensional problem due to the infinite degree of freedom of heat addition. In the present study, the problem of optimizing heat release is viewed from a perspective of functional theory. Different from the previous studies devoted to finding the optimal parameters in the finite-dimensional parameter space, the present study attempts to seek the ideal heat release of supersonic combustion in the infinite-dimensional function space. Further, we formulate the heat release/combustor configuration coupling optimization problem based on functional theory, aiming at finding the ideal heat release and ideal configuration of supersonic combustor. The final purpose of this study is to present the performance limitation of supersonic combustion. The preliminary findings of the study has been published in AIAA J. Propulsion and Power.

通过调节超声速燃烧释热规律来提高发动机性能是一个经典问题。一直以来对于该问题的研究主要是先人为设定有限个燃料喷注点，再通过数值模拟或试验来寻找优化的燃料喷注点位置及流量分配。但是释热规律变化理论上的无穷维自由度使得在人为假定约束下无法得到最优结果，这是对此问题有大量研究而无定论的原因所在。.考察经典问题需要新视角，我们把研究该问题的定义域从参数空间(由燃料喷注点数量、位置及流量分配等所张成)拓展到函数空间(由描述超声速燃烧释热规律的函数所组成)来搜索最佳燃烧释热规律，如此可以结合泛函理论等来对该经典问题进行演绎。并进一步提出了超声速燃烧释热规律/几何构型耦合泛函优化问题，旨在利用数学理论来帮助演绎超声速燃烧室理想释热规律与理想几何构型。该研究的最终意义在于试图通过理论演绎来探索“超声速燃烧的性能极限”。初步研究结果已发表在AIAA J. Propulsion and Power。