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Jets are the most basic flow used in industrial field and are widely used for heating, cooling, mixing. Recently, the improvement of mixing efficiency is required in order to downsize many industrial equipments and upgrade their performance. In the case of jets, their characteristic, such as the diffusion, depends on the inlet condition. Therefore, by controlling jet to give appropriate inlet conditions, the mixing efficiency can be improved. Thus far previous studies have mainly investigated excitation control associated with the instability of jets. However, in our previous study, as a new method we proposed vector control to enhance mixing or diffusion of free jets and have found its characteristics [1]. In this study, we focus on the vector control in which an inflow direction is rotating around the streamwise direction. In order to investigate the performance of the proposed method, the DNS of axisymmetric jet under the vector control are conducted and its structures are visualized; the mixing efficiency based on a mixing measure are quantified; further to make clear the reason for the mixing enhancement, the SPOD(snapshot proper orthogonal decomposition) [2] and the DMD (dynamic mode decomposition) method [3] are applied.
Author(s):
Koichi TSUJIMOTO
Mie University
Japan
Noritaka SHIBATA
Mie University
Japan
Toshihiko SHAKOUCHI
Mie University
Japan
Toshitake ANDO
Mie University
Japan