A new direct-connect supersonic combustor has been designed and tested for the study of plasma-assisted combustion in the ACT-II supersonic combustion tunnel. Laser-induced plasma ignition was investigated in an ethylene-fueled cavity flame holder at Mach 3. Combustor design, geometry, and flow characteristics are discussed in the first part of the paper. The supersonic combustor includes a cavity flame holder, where ethylene fuel is injected, mixed with entrained air, and ignited. Two injector configurations are included, one horizontal and one vertical, which were designed in such a way as to enhance the cavity flow recirculation. Two different plasma ignition mechanisms were considered: 1) a laser-induced plasma located at the center of the cavity, and 2) a spark plug placed on the bottom surface of the cavity. The diagnostics tools tested to characterize the flow include time-resolved pressure measurements, high-speed schlieren visualization and ${\mathrm{OH}}^{*}$ chemiluminescence visualization, and instantaneous planar laser-induced fluorescence of the CH radical. The second part of the paper discusses the results of the comparison between horizontal and vertical fuel injection. The larger backpressurization of the isolator and a more uniform ${\mathrm{OH}}^{*}$ distribution within the cavity suggest a greater heat release and combustion efficiency when the horizontal jet is used.

为了研究ACT-II超音速燃烧隧道中的等离子体辅助燃烧，已经设计并测试了一种新型的直连式超音速燃烧器。在马赫数为3的乙烯燃料腔火焰保持器中研究了激光诱导的等离子体点火。在本文的第一部分中讨论了燃烧器的设计，几何形状和流动特性。超音速燃烧器包括空腔火焰保持器，在其中喷射乙烯燃料，与夹带的空气混合并点燃。包括两种喷射器配置，一种是水平的，一种是垂直的，其设计方式是增强型腔的再循环。考虑了两种不同的等离子体点火机制：1）位于腔体中心的激光诱导等离子体，以及2）置于腔体底面上的火花塞。${哦}^{*}$化学发光可视化，以及瞬时平面激光诱导的CH自由基荧光。本文的第二部分讨论了水平和垂直燃油喷射的比较结果。隔离器的背压更大，更均匀${哦}^{*}$ 当使用水平射流时，空腔内的分布表明更大的热量释放和燃烧效率。