The impact of thermal compression on combustion has been studied experimentally in a hydrogen-fuelled, non-uniform scramjet flowpath. The experimental model consisted of a three-dimensional inlet, a constant area rectangular combustor, and a single-ramp expansion nozzle, all having a constant width, and was tested at an equivalent Mach 10 flight condition with 58 kPa dynamic pressure. Combustion was suppressed in different regions of the combustor by injecting helium as a replacement for hydrogen fuel in either spanwise half of the engine. Thermal compression effects increased the combustion-induced pressure rise by $(11.9\pm 5.8)\text{\%}$ across the majority of the combustor for an equivalence ratio of 0.8, however a shock-related artefact dominated similar measurements for a case with an equivalence ratio of 1.0. Over a smaller region at the end of the combustor, the combustion-induced pressure rise was increased by $(9.4\pm 9.2)\text{\%}$ and $(6.7\pm 6.8)\text{\%}$ for equivalence ratios of 0.8 and 1.0, respectively. Time-integrated OH emission signals increased by 19% and 31%, whilst time-resolved signals increased by 54% and 35%, for equivalence ratios of 0.8 and 1.0, respectively. This study presents the first experimental evidence of thermal compression directly increasing combustion-induced pressure rise in a scramjet engine.

已经在氢燃料非均匀超燃冲压流路中实验研究了热压缩对燃烧的影响。实验模型由三维入口，等面积矩形燃烧室和单斜坡膨胀喷嘴组成，均具有恒定宽度，并在等效马赫数10飞行条件下以58 kPa动态压力进行了测试。通过在发动机的任一展向一半处注入氦气代替氢气来抑制燃烧器不同区域的燃烧。热压缩效应使燃烧引起的压力上升增加了$（11.9\pm 5.8）\text{％}$在当量比为0.8的情况下，燃烧器的绝大部分区域都处于类似状态，但是当当量比为1.0时，与冲击有关的伪像占主导地位。在燃烧器末端的较小区域上，燃烧引起的压力上升增加了$（9.4\pm 9.2）\text{％}$ 和 $（6.7\pm 6.8）\text{％}$当量比分别为0.8和1.0。时间积分OH发射信号分别增加了19％和31％，而时间分辨信号分别增加了54％和35％，当量比分别为0.8和1.0。这项研究提供了热压缩直接增加超燃冲压发动机燃烧引起的压力升高的第一个实验证据。