Hilbert‐Huang Transform Analysis of the Concentration Field of a Two‐Layer Impinging Stream Mixer

Abstract The concentration field of a two‐layer impinging stream mixer was measured by the plane laser‐induced fluorescence (PLIF) technology, and the energy distribution of the concentration field was studied by Hilbert‐Huang transform. The Hilbert spectrum and marginal spectrum under different operational conditions were analyzed in the mixer. It is indicated that the energy of the concentration field firstly increased and then decreased with larger nozzle diameter and nozzle spacing. The energy of the concentration field incremented with the rise of the jet Reynolds number. According to the energy characteristic value P i , the flow field of the impinging stream mixer was divided into three regions. It could provide a quantitative basis for identification of the flow regimes of impinging steam.