Research on Combustion Fluctuation and Compound Choking in SCRAM Jet Engines

SCRAM喷气发动机燃烧脉动与复合壅塞研究

• 批准号: 09450368
• 负责人: KAJI Shojiro
• 金额: $ 8.32万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B).
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-09450368/
• 关键词: supersonic combustion; SCRAM Jet; thermal choking; compound choking; high enthalpy wind tunnel; space plane; hydrogen combustion

The most important problems in supersonic combustion ram jet engines (SCRAM) which are suitable for hypersonic transports and space planes are the phenomena such as thermal choking and compound choking. In the case of integrated SCRAM engines, the boundary layer flow which is developed along the vehicle fuselage is sucked into engines with the main flow. The flow tube of the boundary layer and that of the main flow have the same total temperature but different total pressures and Mach numbers. When they coexist in the engine they behave quite queerly against the cross-sectional area change in the engine and heat addition in each flow tube. The main flow tube is easily choked at supersonic conditions because of the existence of the boundary layer flow, where the static pressure balance is kept between two flow tubes. This phenomenon is called compound choking.The purpose of the present research is to investigate the details of choking phenomena in SCRAM engines and to find out the control rule which is necessary for stable operation of SCRAM engines.In order to realize choking in SCRAM engines, an engine module of 30mm×32.6mm frontal cross section was put in the supersonic wind tunnel of 100mm×100mm cross section driven by the vitiated air of temperature 2000K (maximum) at Mach number 2.0. Self-ignition was realized by injecting hydrogen fuel into the engine module. From the pressure signals measured on the engine wall, it was recognized that supersonic combustion was realized while the injection pressure of hydrogen was low. But when the injection pressure was increased the pressure inside the engine increased indicating subsonic combustion. In such circumstances the region of high pressure was observed to extend in sequence from downstream to upstream in the engine and it finally fell into the unstart condition.

适用于高超音速运输和空间平面的超音速混合物RAM喷气发动机（SCRAM）中最重要的问题是诸如热窒息和复合窒息之类的现象。在集成的SCRAM发动机的情况下，沿车身机身开发的边界层流被主要流动吸入发动机。边界层和主流量的流管具有相同的总温度，但总压力和马赫数不同。当它们在发动机中共存时，他们对发动机的横截面区域的变化和每个流管中的加热都非常奇怪。由于存在边界层流的存在，主流管在超音速条件下很容易被窒息，其中将静压平衡保持在两个流管之间。这种现象称为复合窒息。本研究的目的是调查Scram发动机中窒息现象的细节，并找出Scram发动机稳定运行所必需的控制规则。在Scram引擎中chok the choke choke ins in Scram引擎，为32.6毫米额叶横截面的发动机模块在2000毫米旁的空中置于100mm×100mm×100mm×100mm×100mm的空中， （最大）在马赫数字2.0处。通过将氢燃料注入发动机模块来实现自动点。从发动机壁上测得的压力信号中，可以认识到，在氢的注入压力低时，实现了超音速混合物。但是，当注入压力增加时，发动机内部的压力增加了表明亚音速混合物。在这种情况下，观察到高压区域会从下游到上游延伸，最终陷入了脱离的条件。