Mixing performance of water and glycerol-water solution in a confined impinging jets reactor (CUR) with and without excitation was experimentally studied using planar laser induced fluorescence (PLIF) at 100 <= Re <= 500. The effects of the jet Reynolds number (Re), fluid viscosity and excitation on the oscillation behaviors and mixing performance in CUR have been qualitatively and quantitatively investigated. Results show that for Re <= 100 the flow is segregated with poor mixing; for Re >= 150 the flow evolves to an oscillation regime with strong mixing. Compared with the Reynolds number, the fluid viscosity has an insignificant effect on the mixing in CUR. The mixing in CUR at low jet Reynolds number can be effectively enhanced by excitation with low frequency, as a periodic oscillation is induced by the pulsed inflow, which further causes the continuous folding and stretching of the impingement plane. The enhancement of mixing is strengthened with the increase of excitation amplitude and is weakened with the increase of excitation frequency. (C) 2015 Elsevier Ltd. All rights reserved.