Research On Typical Turbulent Flow Based On Dynamic Mode Decomposition Method

The vortex with different scales interacts with each other and it results in the complicated turbulent flow.The mode decomposition methods based on the flow parameters can extract the coherent structures in complicated turbulent flow field and it can assist us to understand the flow pattern of turbulent flow.In this paper,the flow field of multi-cylinders and the particle flow field of bifurcated pipe were discussed based on the detailed discussion on the mode decomposition methods.Finally,the flow field of the impeller with vaneless diffuser and the impeller with vaned diffuser was discussed.Both the Proper Orthogonal Decomposition(POD)and Dynamic Mode Decomposition(DMD)can extract the coherent structure.The discrepancy of the mode decomposition methods above were discussed by the analytical flow field and the experimental flow field.The DMD were adopted to analyze the turbulent flow in the paper on account of the physical meaning of the modes in DMD.The urans was adopted to simulate the flow field in centrifugal compressor on account of the accuracy of the description of vortex and the computer source.The DMD also can be adopted to analyze picture,the movement law of the particle affected by the reflux vortex was analyzed by the high speed camera picture based on the DMD.The DMD was adopted to extract the coherent structure in the impeller and vaneless diffuser at design condition and near stall condition and the blade tip clearance flow which affect the flow in vaneless diffuser and the flow characteristic in vaneless diffuser at near stall condition were discussed.The DMD was adopted to analyze the flow field in the impeller and vaned diffuser with two set angle.The rotor-stator interaction and the movement of wake at different section of the diffuser were discussed to reveal the unstable phenomenon in diffuser.