Scalar mixing near the turbulent/non-turbulent interface in the planar liquid jet with chemical reaction

Abstract

Chemical reaction near turbulent/non-turbulent (T/NT) interface in liquid phase turbulent flow was investigated experimentally. The concentrations of reactive species near the T/NT interface in a planar liquid jet with a second-order chemical reaction A+B → R was measured with different stoichiometric mixture ratios. The reactants A and B were premixed into the jet and ambient flows, respectively. The optical fiber probe based on the light absorption spectrometry was used to measure the instantaneous concentrations of the reactive species. The T/NT interfaces were separated into two types (i.e. leading edge and trailing edge) and investigated separately. Mean concentration conditioned on the distance from the T/NT interface was calculated. It was found that the thickness where large concentration change of the reactive species occurs are order of Taylor’s microscale and does not depend on stoichiometric mixture ratio. In addition concentration profile of product R near the T/NT interface does not depend on stoichiometric mixture ratio, while equilibrium limit clearly depend on stoichiometric mixture ratio. This means that near the T/NT scalar mixing does not reach molecular level and chemical reaction is not active.

Keywords

• jet
• chemical reaction
• turbulent flow
• mixing
• turbulent/non-turbulent interface