Numerical Study On The Flow Control Mechanism Based On The Lattice Boltzmann Method

This paper sets Boundary Layer Flow Control as its study field, and particularly takes non-thermal plasma induce and control under surface discharge condition as the research object, with the aim of exploring the mechanism of plasma induce and control. Based on the Lattice Boltzmaan Method(LBM), the thesis focuses on study of boundary layer induce and control effect of low temperature plasma generator on the wall boundary layer under different conditions.By building an electric field characteristics model of the plasma actuator, this paper compared and analyzed the influence of structure and size of plasma actuator on the electric field distribution. LBM was employed to simulate the boundary flow control by one plasma actuator. Time-dependent induced flow field and velocity profiles near the solid boundary of three different locations were obtained. The influence of physical parameters on induced effect was analyzed also. Two plasma actuators were placed on a free surface. According to the results, the distance between them influences the continuous induced effect. The induced effect decreases as the distance increases. But the maximum induced velocity decreases non-linear with distance.Simulation on the induced flow field caused by two plasma actuators symmetrically placed in the channel was analyzed. Because of the induced effect of the actuators, vortexs formed in the channel, which had negative effects on the induced flow, that blocked the channel and decreased flow velocity and flow rate. However, as the channel height increased, vortexs drove the air flow in the channel. The induced effect became more obviously, meanwhile, flow velocity and flow rate increased, but the flow direction changed.In this paper, the flat-plate flow which was generated by the plasma actuator on the upper surface was simulated and analyzed. When the plasma intervened at hige angle of attack, the vortexs on the plate disappeard. From the point of lift coefficient, the effect of increasing lift is obvious; while from the view of resistance coefficient, when the stream speed is low, the intervention of plasma reduces the resistance significantly. Moreover, simulation on the NACA0015airfoil flow generated by the plasma actuator on the upper surface was analyzed at the same time. The intervention of plasma could obviously eliminate the vortexs generated by the upper airfoil side at hige angle of attack. After suppressing vortexs and calculating the results, the author notices that the flow distribution is basically in accordance with that of the experiment. From the perspectives of lift coefficient and resistance coefficient, therefore, the effects of increasing lift and decreasing resistance are obvious at hige angle of attack condition.Furthermore, a new multi-components model to simulate the induced flow by plasma was build. In this model, the plasma ionization, recombination and charge attachment among electrons, positive ions, and negative ions had been considered. By simulating an induced flow by surface dielectric barrier discharge plasma actuator, the distributions of electrons, positive ions, and negative ions near the solid wall were obtained. The simulation presents that the flow field and velocity profile near the surface are in agreement with the results of previous paper.The mean-field lattice boltzmann model was also employed to study capillary penetration problem. The results of distance vs.t1/2with different contact angles were obtained, which are consistent with those anticipated from the Washburn equation.