Scramjet Engine Flowpath That Improves Specific Impulse Using JP-7 Fuel

IF 1.7 4区工程技术 Q2 ENGINEERING, AEROSPACE

Journal of Propulsion and Power Pub Date : 2023-04-16 DOI:10.2514/1.b38931

Yunseok Choi, J. Driscoll

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Abstract

A flowpath geometry was computed that improves the specific impulse of a dual-mode scramjet engine in a generic X-51 hypersonic vehicle. Six parameters were varied: inlet contraction ratio, the diameters and numbers of fuel injectors, divergence angle of the combustor wall, nozzle flap deflection angle, and flight Mach number. The maximum specific impulse [Formula: see text] was 2296 s in the ram mode and 832 s in the scram mode. A reduced-order model simulates the finite-rate chemistry of JP-7 fuel and the unstart limits. Results show that both combustion efficiency and [Formula: see text] drop to unacceptably low levels when the finite-rate chemical reaction rates are weakened by flame strain-out due to the large air velocities, or when the flame becomes longer than the combustor. Small [Formula: see text] occurs when the following are too small: the inlet contraction ratio, the inlet compression ratio, the number of fuel injectors, and the diameter of fuel injectors. When these parameters are too large, excessive heat release causes unstart. The operating range was identified between these limits. For JP-7 fuel, it was found that the inlet should raise the pressure to above 5 atm. Results are explained by the interactions between reactions, mixing, and flame strain-out.

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使用JP-7燃料提高比冲的超燃冲压发动机流道

计算了一种流道几何形状，该几何形状改善了X-51高超音速飞行器中双模超燃冲压发动机的比冲。改变了六个参数：入口收缩比、燃料喷射器的直径和数量、燃烧室壁的发散角、喷嘴襟翼偏转角和飞行马赫数。冲压模式下的最大比冲[公式：见正文]为2296 s，紧急停堆模式下为832 s。一个降阶模型模拟了JP-7燃料的有限速率化学和不启动极限。结果表明，当有限速率的化学反应速率因大空气速度导致的火焰应变而减弱时，或者当火焰变得比燃烧器长时，燃烧效率和[公式：见正文]都降至不可接受的低水平。当以下因素太小时，就会出现小[公式：见正文]：进气收缩比、进气压缩比、喷油器数量和喷油器直径。当这些参数过大时，过多的热量释放会导致不启动。确定了这些限值之间的工作范围。对于JP-7燃料，发现入口应将压力升高到5atm以上。结果通过反应、混合和火焰应变之间的相互作用来解释。

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来源期刊

Journal of Propulsion and Power 工程技术-工程：宇航

CiteScore

4.20

自引率

21.10%

发文量

审稿时长

6.5 months

期刊介绍： This Journal is devoted to the advancement of the science and technology of aerospace propulsion and power through the dissemination of original archival papers contributing to advancements in airbreathing, electric, and advanced propulsion; solid and liquid rockets; fuels and propellants; power generation and conversion for aerospace vehicles; and the application of aerospace science and technology to terrestrial energy devices and systems. It is intended to provide readers of the Journal, with primary interests in propulsion and power, access to papers spanning the range from research through development to applications. Papers in these disciplines and the sciences of combustion, fluid mechanics, and solid mechanics as directly related to propulsion and power are solicited.