24-10-2012, 10:36 AM
Numerical Investigation of Dual-Mode Scramjet Combustor with Large Upstream Interaction
ABSTRACT
Dual-mode scramjet combustor configuration with significant upstream interaction is investigated numerically, The
possibility of scaling the domain to accelerate the convergence and reduce the computational time is explored. The supersonic
combustor configuration was selected to provide an understanding of key features of upstream interaction and to identify
physical and numerical issues relating to modeling of dual-mode configurations. The numerical analysis was performed with
vitiated air at freestream Math number of 2.5 using hydrogen as the sonic injectant. Results are presented for two-dimensional
models and a three-dimensional jet-to-jet symmetric geometry. Comparisons are made with experimental results. Twodimensional
and three-dimensional results show substantial oblique shock train reaching upstream of the fuel injectors. Flow
characteristics slow numerical convergence, while the upstream interaction slowly increases with further iterations. As the
flow field develops, the symmetric assumption breaks down. A large separation zone develops and extends further upstream
of the step. This asymmetric flow structure is not seen in the experimental data. Results obtained using a sub-scale domain
(both two-dimensional and three-dimensional) qualitatively recover the flow physics obtained from full-scale simulations. All
results show that numerical modeling using a scaled geometry provides good agreement with full-scale numerical results and
experimental results for this configuration. This study supports the argument that numerical scaling is useful in simulating
dual-mode scramjet combustor flowfields and could provide an excellent convergence acceleration technique for dual-mode
simulations.