Daiki Muto

Numerical Simulation of Jet Mixing in a Recessed Coaxial Injector at Supercritical Pressure

Three-dimensional numerical simulations of cryogenic coaxial jets under supercritical pressure are performed with flushed and recessed injectors to investigate the effect of a recess on the coaxial mixing. A hybrid ILES/RANS method is applied to simulate wallbounded injectors and a recessed region. The recessed injector enhances the density decay and the temperature increase on the central axis, indicating the improvement of mixing compared with the flushed injector. However, the mixing improvement by the recess is not significant in the present conditions. The recess also induces distinct vortex rings around the outer jet. The power spectra of the velocity fluctuations also demonstrated that the low-frequency velocity fluctuations are clearly induced by the recess which frequency corresponds to the large vortex structures.

Effects of Injector Geometry on Co-Flowing Planar Jet Mixings under Supercritical Pressures

The effects of the injector geometries on co-flowing planar cryogenic jet mixings under a supercritical condition are numerically investigated. The present study focuses the recess of the coaxial injector which is widely applied in practical liquid rocket engines. The present numerical method applies an ILES/RANS hybrid method to simulate the jet mixing in the wall-bounded recessed region. As a validation of the present method, a mono-planar jet and a round jet simulations are carried out, and the results agree well with an experimental result. To examine the effects of the recess length on the coaxial injections, two-dimensional co-planar jet simulations at the supercritical pressure are performed in three recess lengths. The recessed cases show the strong flapping motions of the high densty jet, and as a result, the injected fluids are mixed well compared with the case without the recess. While there is a small difference on the potential core length between the cases without the recess and the shorter recess, the longer recess case largely shortens the jet core.