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Development of GOX/Hydrocarbon Multi-Element Swirl Coaxial Injector Technology

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Technical paper for 20-23 Jul 2002

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In developing the advanced liquid rocket engine, injector design is critical to obtaining the dual goals of long engine life as well as providing high-energy release efficiency in the main combustion chamber. Introducing a swirl component in the injector flow can enhance the propellant mixing and thus improve engine performance. Therefore, swirl coaxial injectors, which swirl liquid fuel around a gaseous oxygen core, show promise for the next generation of high performance staged combustion rocket engines utilizing hydrocarbon fuels. Understanding the mixing and combustion characteristics of the swirl coaxial flow provides the insight of optimizing the injector design. A joint effort of Sierra Engineering Sierra and the Propulsion Directorate of the Air Force Research Lab AFRL was conducted to develop a design methodology, utilizing both high-pressure cold-flow testing and uni-element hot-fire testing, to create a high performing, long life swirl coaxial injector for multi-element combustor use. Several swirl coax injector configurations designed and fabricated by Sierra have been tested at AFRL. The cold-flow tests and numerical simulations have been conducted. The cold flow result provided valuable information of flow characteristics of swirl coaxial injectors. However, there are two important flow features of liquid rocket engines missed from the cold flow test 1 the effect of combustion on the propellant mixing, and 2 the interaction of multiple injectors. The present work studies the hot flow environment specifically the multiple element swirl coaxial injector. Numerical simulations were performed with a pressure-based computational fluid dynamics CFD code, FDNS. CFD results produced loading environments for an ANSYS finite element thermalstructural model. Since the fuels are injected at temperature below its critical temperature, the effect of phase change and chemical reactions needs to be accounted for in the CFD model.

Subject Categories:

  • Inorganic Chemistry
  • Combustion and Ignition
  • Fuels

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