Modern rockets operate at supercritical pressures with respect to propellants. There is a need to understand mixing and combustion beyond liquid and gas states. Shear coaxial injectors are a common choice for cryogenic liquid rocket engines. Interactions of transverse acoustics with an injector's own modes and mixing need to be understood in terms of combustion instability. There is a need to understand the differences in response to pressure and velocity ...
This experimental study investigated the response of dynamic flow structures of cryogenic coaxial nitrogen jets to pressure perturbations due to transverse acoustic forcing at a pressure antinode (PAN). The role of injector exit geometry on the flow response was examined using two shear coaxial injectors with different outer-to-inner jet area ratios. Flow conditions spanning subcritical (reduced pressure of 0.44) to supercritical (reduced pressure of 1.05) chamber pressures, varying outer-to-inner jet ...
An investigation of the mixing enhancement behavior of N2 shear coaxial jets between two injector geometries is presented. A total of 20 cases with one injector geometry and 15 with the other, corresponding to different momentum flux ratios (J's) at subcritical, nearcritical and supercritical pressures are analyzed and compared. The measurements are extracted from 998 backlit images. Acoustic excitation is used to analyze the response of the system to velocity ...
A new technique to delay transition to turbulence in hypervelocity air flows is introduced and investigated in this work. The main motivation for such a technique is the pressing need to reduce aerodynamic heating rates on hypersonic vehicles. Turbulent heat transfer rates can be an order of magnitude higher than laminar rates at hypersonic Mach numbers. Hence, schemes to delay transition to turbulence could provide an important means to reduce ...
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