INJECTION OF FLUIDS INTO SUPERCRITICAL ENVIRONMENTS
This paper summarizes and compares the results of systematic research programs at two independent laboratories regarding the injection of cryogenic liquids at subcritical and supercritical pressures, with application to liquid rocket engines. Both single jets and coaxial jets have been
studied. Cold flow studies provided valuable information without introducing the complexities of combustion. Initial studies utilized a single jet of cryogenic nitrogen injected into a quiescent room temperature nitrogen environment with pressures below and above the thermodynamic critical
pressure of the nitrogen. Later, the work was extended to investigate the effects of a co-flowing gas. Parallel to this work, combustion studies with cryogenic propellants were introduced to understand high pressure coaxial injection phenomena with the influence of chemical reaction. Shadowgraphy
and spontaneous Raman scattering were used to measure quantities such as growth rates, core lengths, turbulent length scales, fractal dimensions, and jet breakup regimes. It is found that jets injected at supercritical pressures do not atomize as they do at subcritical pressures. Rather, they
behave in many respects like variable density turbulent gas jets.
Document Type: Research Article
German Aerospace Center (DLR), Institute of Space Propulsion, Lampoldshausen, Germany
Engineering Research Consultants, Lancaster, Pennsylvania, USA
U.S. Air Force Research Laboratory (AFRL), Propulsion Direct orate, Edwards Air For ce Base, California, USA
January 1, 2006
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