预燃/流向涡掺混超声速燃烧室的稳焰火炬实验研究

 为研究飞行马赫数Ma_flight=4~7的双燃室碳氢燃料超燃冲压发动机燃烧室的原理和工程参数,进行了直连双燃室超声速冷主流和亚燃室稳焰火炬热流的掺混实验和燃烧实验。将进气道输出的超声速气流的10%流量经亚燃进气道导入亚声速预燃室,先低速地与雾化预燃油掺混并建立稳定的预燃。该预燃气流与二次喷入的主燃油掺混而形成富含吸热分解油气的高温射流,再经一组波瓣掺混器与超声速主流在下游流向涡中深入掺混/燃烧,扩大燃区厚度而趋于深入超声流层,以期实现稳定超燃。在总温约为285 K、总压为1.5×10⁶ Pa和1.0×1.0⁶ Pa,燃烧室进口马赫数Ma_inlet=2.5的来流下,对3种不同结构参数的预燃室和一种超燃室,进行了冷态流场和预燃/主燃的喷油/燃烧实验。实验与计算结果表明,冷/热态实验中整个超燃室保持了超声速流动,尽管斜激波系存在一些变化。利用存在的4种旋涡掺混现象,增强超/亚声速流之间的掺混。当采用三波系进气道和较小容积热强度的大体积预燃室和流向涡掺混器,可以形成稳定的高温富油火炬,成为超燃室稳定点火源。在超燃室下层流层的原无预热冷态来流的亚声速和低超声速区域中出现火焰,且其并不破坏超燃室上层的高超声速未燃流动。

Experimental Study on Flame Holding Torch of a Hydrocarbon Fueled Combined Supersonic Combustor with a Pilot Burner and a Streamwise-vortices Generator

To investigate the principle and parameters of the flight Mach number Maflight=4-7 hydrocarbon fueled dual-combustor scramjet engine,we perform the experimental studies of both cold flow field mixing and combustion on a direct-connected combined supersonic combustor with a flame holding torch formed by a small pilot burner and a streamwise vortice generator.Let 10% inlet outlet supersonic flow again into the pilot burner,in which the air experiences the first air fuel spray mixing and a stable subsonic pilot combustion.The pre-combustion gas then mixes secondly with the major fuel injection stream to form a hot torch with rich and partly decomposed fuel.The torch effluent then passes a group of lobed mixer and emits into the supersonic main flow.This confluent flow is designed to generate a streamwise-vortices mixing and,by immersing gradually from the layer of subsonic flow into the layer of supersonic flow,to induce an efficient and stable supersonic combustion.Three pilot burners and one supersonic combustor are used in the experiment of cold air through flow,fuel injection and ignition under the conditions of combustor inlet Mach number Mainlet=2.5,total pressure 1.5×106 Pa and 1.0×106 Pa,total temperature 285 K.The experiment and calculation indicate that the main flow in the supersonic combustor keeps supersonic,though the oblique shock train slightly moves while dual-combustor is ignited.There are four kinds of vortices phenomena which enhance the mixing between subsonic and supersonic flows.The combination of a triple-shock inlet and a small volumetric-heat-intensity combustor with the lobed mixer could realize a stable torch flame as a stabilized holder of the supersonic combustion.In this combustor,the second area of flame has been found in the original cold flow region of subsonic and low-supersonic flows within the supersonic combustor,without the destruction of the supersonic flow state of the upper flow-layers.