Numerical Study of Flow Turning Phenomenon.

The objective of the present research work is an understanding of the physical mechanisms by which energy is exchanged between the mean and acoustic flow fields in resonant combustion chambers (in particular, solid rocket motors). These processes may alter the balance between sources and sinks of oscillatory energy in the combustor significantly and thus are critical to our ability to predict the stability characteristics of proposed motor designs. The present report concentrates on the description and analysis of the computational results obtained to date in the study of acoustic refraction and flow turning phenomena. Three studies were conducted. The time-dependent compressible Navier Stokes equations were solved utilizing an implicit, non-iterative Linearized Block Implicit scheme. In the first study acoustic wave propagation in a tube with a coexisting sheared mean flow was investigated. The results demonstrate that acoustic refraction effects, i.e., the growth of acoustic pressure near the wall (for downstream propagation), are significant., In addition, the results demonstrate acoustic energy transfer to the mean flow as well as Richardson's annular effect. To the best of the authors' knowledge these are the first solutions demonstrating either Richardson's annular effect or refraction effects that are obtained through solution of the complete Navier-Stokes equations.