Joint statistics between velocity and reactive scalar in a turbulent liquid jet with a chemical reaction

Joint statistics between the velocity and the concentration of reactive species are experimentally investigated in a planar liquid jet with a second-order chemical reaction A + B → R. Reactant species A and B are premixed in a jet flow and a main flow, respectively. An optical fibre probe based on light absorption spectrometry is used to measure the instantaneous concentrations of reactive species. The stream-wise velocity and the concentrations of reactive species are simultaneously measured by combining the optical fibre probe with I-type hot-film anemometry, and we investigate the influence of the chemical reaction on correlation coefficients, joint probability density functions and cospectra of u and γi, where u is the stream-wise velocity fluctuation and γi is the concentration fluctuation of species i. The results show that the absolute value of the correlation coefficient between u and γB becomes small owing to the chemical reaction, whereas that between u and γA becomes large on the jet centreline. It is also shown that the influence of the chemical reaction on the cospectrum of u and γi in the upstream region and near the jet centreline is different from that in the downstream region and the outer edge of the flow. (paper)