This paper presents an experimental investigation on flow field induced by a dielectric barrier discharge(DBD) plasma actuator with serrated electrodes in still air to further improve its flow control effectiveness. F...This paper presents an experimental investigation on flow field induced by a dielectric barrier discharge(DBD) plasma actuator with serrated electrodes in still air to further improve its flow control effectiveness. For comparison, the actuator with widely used linear electrodes was also studied. Experiments were carried out using 2D particle image velocimetry. Particular attention was given to the flow topology, discharge phenomenon, and vortex formation mechanism. Results showed that a 2D wall jet was induced by the linear actuators, whereas the plasma actuators with serrated electrode introduced a series of streamwise vorticities, which might benefit flow control(e.g., enhancing the momentum transport in the separated boundary flow). In addition, the mechanism of 3D flow topology induced by the serrated DBD actuator was analyzed in detail.展开更多
The relationship between the maximum shear stress in a substrate solid and the elastic wave reflection coefficient from the interface between the substrate solid and an overlying solid half-space is investigated. Both...The relationship between the maximum shear stress in a substrate solid and the elastic wave reflection coefficient from the interface between the substrate solid and an overlying solid half-space is investigated. Both substrate and overlying solid media are assumed to be initially isotropic and stress-free. Then as the substrate is subjected to horizontal confined stresses it becomes anisotropic. It is shown that longitudinal and shear wave reflection coefficients are related to the degree of stress induced anisotropy in the substrate medium. From this relation the confined stress level and the maximum shear stress generated on the vertical planes of the substrate are estimated. Authors in their previous investigation computed plane wave reflection coefficient in a biaxially compressed solid substrate immersed in a fluid. This paper reports for the first time how the maximum shear stress in a biaxially compressed substrate medium can be measured from the plane wave reflection coefficients when the overlying medium is also a solid half-space.展开更多
基金supported by the National Natural Science Foundation of China (51222606)
文摘This paper presents an experimental investigation on flow field induced by a dielectric barrier discharge(DBD) plasma actuator with serrated electrodes in still air to further improve its flow control effectiveness. For comparison, the actuator with widely used linear electrodes was also studied. Experiments were carried out using 2D particle image velocimetry. Particular attention was given to the flow topology, discharge phenomenon, and vortex formation mechanism. Results showed that a 2D wall jet was induced by the linear actuators, whereas the plasma actuators with serrated electrode introduced a series of streamwise vorticities, which might benefit flow control(e.g., enhancing the momentum transport in the separated boundary flow). In addition, the mechanism of 3D flow topology induced by the serrated DBD actuator was analyzed in detail.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41474098, 11134011)by State Key Laboratory of Acoustics (Grant No. SKLA201608)
文摘The relationship between the maximum shear stress in a substrate solid and the elastic wave reflection coefficient from the interface between the substrate solid and an overlying solid half-space is investigated. Both substrate and overlying solid media are assumed to be initially isotropic and stress-free. Then as the substrate is subjected to horizontal confined stresses it becomes anisotropic. It is shown that longitudinal and shear wave reflection coefficients are related to the degree of stress induced anisotropy in the substrate medium. From this relation the confined stress level and the maximum shear stress generated on the vertical planes of the substrate are estimated. Authors in their previous investigation computed plane wave reflection coefficient in a biaxially compressed solid substrate immersed in a fluid. This paper reports for the first time how the maximum shear stress in a biaxially compressed substrate medium can be measured from the plane wave reflection coefficients when the overlying medium is also a solid half-space.
