Numerical simulation of jet flows and flames

An implicit type of numerical algorithm with a strictly treated pressure solver is developed to investigate coherent instability vortical structures of jet flows and flames. With careful treatments of the pressure and boundary conditions in the solution algorithm the general dynamic instability behaviors and spectral characteristics of the natural jet flows and flames are successfully simulated without artificial addition of disturbances in the numerical simulation. The buoyancy-induced outer vortices are found to make apparent stretching on the flame, resulting in flame flickering and bulges and neckings along the flame surface. When passing through the flame tip, outer vortices experience a split-and-merge process. In the high-speed jet flame; the passage of the outer vortices impedes the formation of the small inner vortices and when outer vortices get close to the inner vortices in the downstream region the strong interactions would dissipate the outer vortices.