Investigation of Transcritical Shear flow’s Dynamics in the GH2/LOX and GCH4/LOX Cryogenic Flames with Real Gas SLFM

The dynamics of transcritical shear flames of GH2-LOX and GCH4-LOX has been investigated numerically. Present results have been compared with available experimental data that show reasonable agreement. The standard k-ε model is applied to simulate flow field. For the combustion and turbulence interaction a steady laminar flamelet model (SLFM) with real gas table has been adapted. Real gas flamelet tables obtained from the Cantera open source code. Initially, it is observed that in the physical space, the difference between real gas condition and ideal gas is significant in terms of the position and dimensions of the flame for the transcritical state. In the mixture fraction space, there is no significant difference between the real gas solution and the ideal gas. However, in near extinction point there is considerable difference. On the other hand it is shown that in the transcritical shear flames the mass flux ratio of fuel and oxidizer is most important parameter from view-point of flame shape and dimension. With increase of the mass flux ratio, the turbulent viscosity and heat transfer in the shear layer increases drastically. Accordingly, the pseudo-boiling phenomenon causes the flame shape and dimension changed remarkably. In the GCH4-LOX flame due to higher density of methane, at the lower mass flux ratio (about 5), a strong recirculation appeared in the front of the flame, while in the GH2-LOX flame this vortex formed around mass flux ratio of 25.