Valery Zhdanov

Analysis of Mixing Processes in Jet Mixers Using LES under Consideration of Heat Transfer and Chemical Reaction

The paper presents an overview of the results on turbulent mixing of inert and reacting flows in a co-axial jet mixer at high Reynolds and Schmidt numbers. Flow modes without a recirculation zone (j-mode) and with intense separation and development of a recirculation zone (r-mode) are considered. The study has been performed using numerical (RANS, LES) and experimental methods (LDV, PLIF). Performances of various numerical models to predict passive scalar mixing and reacting flows are discussed. The influence of various parameters on mixing, the structure of a scalar field and its dissipation field, multifractal properties of the dissipation field and isotropy of the scalar field are studied for the case of passive scalar mixing. Concentrations of the neutralisation reaction product and the mixture fraction are measured simultaneously using the PLIF. A few RANS and LES models are validated by comparing with the PLIF measurements. The influence of various parameters on the selectivity of competitive-consecutive reaction is analyzed using the RANS.

Numerical and Experimental Study of Turbulent Processes and Mixing in Jet Mixers

ABSTRACT Velocity and passive scalar fields in a co-axial jet mixer have been investigated both experimentally (LIF and LDA) and numerically (LES) in a single phase incompressible flow at different flow rate ratios, flow densities, Reynolds numbers and temperatures. Two flow regimes with and without recirculation zone are considered. The flow in the recirculation zone is unsteady and contains coherent vortex structures which enhance sufficiently the mixing of scalars. Different SGS closure models have been tested by comparing with experimental data. The best results were achieved using the dynamic mixed model. The experimental and numerical investigations showed that the mixing is mostly influenced by the flow rate ratio. The effect of other parameters is negligible.