Large Eddy Simulations of Supercritical Multicomponent Mixing Layers
Final technical rept. 1 Mar-31 Aug 2000
JET PROPULSION LAB PASADENA CA
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A study of fuel disintegration and mixing in a supercritical environment was undertaken. The approach was based on a model describing a supercritical, temporal mixing layer and on the utilization of Direct Numerical Simulations DNS . The database from a DNS of a temporal, binary species, initially density stratified, excited mixing layer that did not reach transition was enlarged and scrutinized. The scrutiny was based on the development of the entropy equation for a supercritical fluid and on the examination of contributions to the irreversible entropy production the dissipation. The lack of transition was due to the formation of regions of large density gradients that damped the emerging turbulent scales. To obtain transition, the Reynolds number, as well as the amplitude of the initial excitation, were increased. Two new databases were created for initial Reynolds numbers of 500 and 600. The two new databases were examined to determine the phenomena responsible for vorticity production. Most of the spanwise vorticity production was due to stretchingtilting, and most of the contribution to the vorticity magnitude was due to the viscous terms. The regions of large density gradients created during roll-up and pairing persisted at transition, and the fluid in these regions was non-ideal and consisted primarily of the entrained fluid, with small amounts of entraining fluid dissolved in it.
- Fluid Mechanics