This study experimentally investigated the combustion process in a cavity-based supersonic combustor at the inflow condition of Mach 2.92 with stagnation pressure 2.6 MPa and stagnation temperature 1530 K. Time-averaged flame distribution and oscillation characteristics were revealed by post-processing CH* chemiluminescence images. Wall pressures along the combustor bottom wall were also measured to provide quantitative information. Representative cascaded injection set-ups upstreaming the cavity were selected to compare ethylene flame characteristics. It is found that the combustion process is approaching thermal chocking when increasing the equivalence ratio to 0.8 according to the one-dimensional analysis of the Mach number distribution. At the same equivalence ratio, increasing the number of the cascaded injectors by lowering the injection pressure is not beneficial for the combustion enhancement, indicating that the injection pressure is also a key factor affecting the combustion heat release. However, increasing the injection pressure can cause obvious flame oscillations above the cavity as well as increasing the axis distance of the injectors. As a result, the injection scheme with two cascaded injectors which have the injection distance of 0.1 and 0.4 time the length of the cavity floor, respectively, upstreaming the cavity is suggested as a favorable scheme for scramjet applications.

本研究通过实验研究了空腔超音速燃烧器在流入条件为 2.92 马赫、停滞压力 2.6 MPa 和停滞温度 1530 K 下的燃烧过程。通过后处理 CH* 化学发光图像揭示了时间平均火焰分布和振荡特征. 还测量了沿燃烧器底壁的壁压以提供定量信息。选择腔上游的代表性级联注入装置来比较乙烯火焰特性。根据马赫数分布的一维分析，当当量比增加到0.8时，燃烧过程接近热阻塞。在相同的当量比下，通过降低喷射压力来增加级联喷射器的数量不利于燃烧增强，说明喷射压力也是影响燃烧放热的关键因素。然而，增加注射压力会导致腔上方明显的火焰振荡以及增加喷射器的轴线距离。因此，建议在腔上游具有两个级联喷射器的喷射方案，它们的喷射距离分别为腔底长度的 0.1 倍和 0.4 倍，作为超燃冲压发动机应用的有利方案。增加注射压力会导致型腔上方明显的火焰振荡以及增加喷射器的轴距。因此，建议在腔上游具有两个级联喷射器的喷射方案，它们的喷射距离分别为腔底长度的 0.1 倍和 0.4 倍，作为超燃冲压发动机应用的有利方案。增加注射压力会导致型腔上方明显的火焰振荡以及增加喷射器的轴距。因此，建议在腔上游具有两个级联喷射器的喷射方案，它们的喷射距离分别为腔底长度的 0.1 倍和 0.4 倍，作为超燃冲压发动机应用的有利方案。