Abstract: The study investigates the energy distribution patterns within the flow field of a dynamic impact stream reactor through a combination of experimental and theoretical analysis. The flow field inside the dynamic impact stream reactor is measured using TR–PIV (Time-Resolved Particle Image Velocimetry) technology. Various nozzle spacings, different outlet mean velocities, and different outlet velocity differences are examined to understand the flow structure and energy distribution within the reactor. By performing eigenvalue orthogonal decomposition on the two-dimensional velocity field within the dynamic impact stream reactor, different scale quasi-ordered structures within the flow field and energy characteristics under different eigenmodes are extracted. Large-scale coherent structures in the flow field are distributed in the radial jet region and near the wall surface below the two nozzles. The energy of low-order modes in the reactor's flow field initially increases and then decreases as the nozzle spacing increases, with the highest energy proportion observed at a nozzle spacing of L/d = 4. The energy also increases with increasing outlet mean velocity and outlet velocity difference. Under dynamic outlet conditions, the energy proportion in the flow field of the impact stream reactor is higher, and the large-scale coherent structures in the flow field are more pronounced. This significantly enhances momentum exchange within the flow field, contributing to improved mixing efficiency.