Conditional statistics in a liquid jet with a chemical reaction

Abstract

Instantaneous velocity and reactive concentrations are simultaneously measured in a planar liquid jet with a secondorder chemical reaction (A+B→R) by combining an I-type hot film probe with an optical fiber probe based on the light absorption spectrometry. Conditional statistics conditioned on the mixture fraction ξ are investigated experimentally. The results show that the reactive concentrations strongly depend on ξ . It is also shown that the conditional mean concentration is close to the concentration at the frozen limit in the upstream region of the jet, and in the downstream direction, the conditional mean concentration becomes close to the concentration at the equilibrium limit because of the reaction progress. The rms value of reactive concentration fluctuation is small compared with the conditional mean concentration. In the conditional moment closure methods, the conditional mean reaction rate is often approximated by using the conditional mean concentration of reactant species. The results show that the conditional mean reaction rate is well approximated by using the product of conditional mean concentrations of reactant species A and B. It is found that the conditional statistics measured in the downstream region is little dependent on the lateral position of the jet flow. ©2013 The Japan Society of Mechanical Engineers.