A Study on Control of Supersonic Combustion using Mixing Enhancement by Instability Excitation

本研究的目的是实验研究燃料和空气的混合增强和超声速空气流中的燃烧增强。声扰动的注入激发了燃料流与空气流之间形成的混合层的不稳定性。位于流动通道壁上的空腔被用作声干扰源。混合增强预计将出现声扰动，因此燃烧效率预计将增加。非燃烧实验：实验没有燃烧进行的第一阶段，以调查声学扰动对混合层的生长的影响。氢作为气体燃料平行于超音速空气流喷射。将声扰动注入超声速混合层，以探讨声扰动对混合的强化作用。混合层中的先导压力分布的测量是 关于我们 实验结果表明，声扰动对混合层的生长速率有明显的促进作用，这表明声扰动的注入对增强空气与燃料的混合是有效的。燃烧实验表明，声扰动的注入对混合层的生长速率有明显的促进作用。为了研究上述混合增强对燃烧行为的影响，将声学扰动注入到燃烧混合层中，获得燃烧效率。燃烧效率由燃烧室中测得的壁面压力分布获得。结果表明，超声速燃烧室中存在声扰动时，燃烧效率比无声扰动时高，且在超声速燃烧室中出现了稳定的强燃烧模式，这表明声扰动的引入有利于超声速流场中的混合增强和燃烧效率的提高。少

The objective of the present study is to investigate experimentally mixing enhancement of fuel and air and combustion enhancement in supersonic air flows. The instability of the mixing layer which formed between air flow and fuel flow is excited by injection of the acoustic disturbances. The cavity which is located on the wall of the flow channel is used as the source of acoustic disturbances. The mixing enhancement is expected to be appeared by acoustic disturbances, and consequently the combustion efficiency is expected to increase.Non-Combustion Experiments : Experiments without combustion are conducted at the first stage in order to investigate effects of acoustic disturbance on the growth of the mixing layer. Hydrogen is injected as a gaseous fuel parallel to the supersonic air flow. The acoustic disturbance is injected to the supersonic mixing layer in order to explore mixing enhancement by acoustic disturbances. Measurements of Pilot pressure distribution in the mixing layer is … More conducted and Schlieren photography is used for the visualization of the mixing layer by a CCD camera with the image intensifies The results show that the growth rate of the mixing layer is larger with the acoustic disturbance than that without it. This suggests that the injection of the acoustic disturbance is effective for the enhancement of the mixing of air and fuel.Combustion Experiments : The acoustic disturbance is injected to the mixing layer with combustion and the combustion efficiency is obtained in order to investigate effects of mixing enhancement mentioned above on the combustion behavior. The combustion efficiency is obtained from the measured wall pressure profiles in the combustion chamber. The combustion efficiency with the acoustic disturbance is larger than that without it. The results also show that the intense combustion mode appears stably using acoustic disturbances.These results indicate that, the injection of the acoustic disturbance is useful for the enhancement of mixing and increase in the combustion efficiency in the supersonic flow. Less