Parametric Study of Advanced Mixing of Fuel/Oxidant System in High Speed Gaseous Flows and Experimental Validation Planning

摘要

This report results from a contract tasking Institute of High Temperatures RAS (IVTAN) as follows: One of the main problems of stable combustion in high-speed flow is an effective mixing of gaseous fuel and oxidant providing full combustion during the resident time in combustor chamber. Generally speaking in-flow mixing consists of two main mechanisms: kinematics mixing (convection) and molecular diffusion. The latter is a final stage of mixing needed to provide extended combustible mixture. Kinematics mixing is more effective in vortex flows; the higher vorticity the better kinematics mixing which means the larger fuel/oxidant interface surface. The second mixing mechanisms diffusion forms a reacting volume estimated as the interface surface times diffusion length. Both interface surface and diffusion length are increasing functions of time. Having these two functions explicitly one can calculate a reacting volume formation and, with chemical kinetics scheme known, the combustion process can be described in detailed. Such an approach has been developed in IVTAN for simulation of highspeed flow of chemically reacting mixture for plasma chemistry applications and simulation of combustion in compressor-type chemical reactors basing on Diesel engine. Because of very short residence time is typical of ram/scram jet operation conditions the measures providing a significant increasing rate of reacting volume are very actual. The proposed Advanced Mixing approach is to increase the reacting volume growth by (1) pulse electrical discharge - JE energy release and (2) by MHD interaction - JB body force. Furthermore it was found recently both experimentally and theoretically 1 that under certain conditions typical of so called Plasma Aerodynamics experiments the filamentary structure of high frequency discharge (streamer discharge) results some times counterflow jet formation.