共查询到19条相似文献,搜索用时 781 毫秒
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分布在弱电介质溶液中的电磁力(Lorentz力),可以有效地控制边界层的流动.利用以转动水槽为主的实验系统和基于双时间步Roe格式的数值方法,对翼型绕流的电磁控制进行了实验和数值研究.结果表明,对于一定攻角的翼型,电磁力可以控制其绕流形态.当电磁力方向与流动方向相同时,可以抑制分离,消除涡街,其效果与减小攻角类似.当电磁力的方向与流动方向相反时,可在流场中形成大涡组成的涡街,增强流体的混合能力,其效果与增大攻角类似.
关键词:
电磁力
翼型绕流
流体控制 相似文献
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用DES数值模拟分离绕流中的旋涡运动 总被引:1,自引:0,他引:1
脱体涡模拟(Detached-Eddy Simulation,DES)是近年来出现的一种结合雷诺平均方法和大涡数值模拟两者优点的湍流模拟方法.采用基于Spalart-Allmaras方程模型的DES方法,数值求解Navier-Stokes方程,模拟绕流发生分离后的旋涡运动.其中空间区域离散采用有限体积法,方程空间项和时间项的数值离散分别采用Jameson中心格式和双时间步长推进方法.通过模拟圆柱绕流以及翼型失速绕流,观察到了与物理现象一致的旋涡结构,得到与实验数据相吻合的计算结果. 相似文献
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本文给出了求解多段翼型位流准确解的一种方法。采用求解拉普拉斯方程把多段翼型绕流区域变换成一个有限矩形域,然后把此矩形域变换成多个圆,从而通过求绕多个圆的准确位流解来求得绕多段翼型位流的准确解。本文提供的方法能广泛应用到任意外形的多段翼型位流计算。采用这种方法计算所得的位流压力分布与用其它方法求得的压力分布非常吻合。 相似文献
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分布在弱电介质溶液中的电磁力(Lorentz力),可以有效地控制边界层的流动.利用以转动水槽为主的实验系统和基于双时间步Roe格式的数值方法,对翼型绕流的电磁控制进行了实验和数值研究.结果表明,对于一定攻角的翼型,电磁力可以控制其绕流形态.当电磁力方向与流动方向相同时,可以抑制分离,消除涡街,其效果与减小攻角类似.当电磁力的方向与流动方向相反时,可在流场中形成大涡组成的涡街,增强流体的混合能力,其效果与增大攻角类似. 相似文献
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研究翼型绕流的转捩预测方法,对于翼型流动细节的精确模拟和气动力的准确计算以及精细化设计均具有十分重要的意义.采用动模态分解(dynamic mode decomposition,DMD)代替线性稳定性理论(linear stability theory,LST)与eN方法结合,不需要求解稳定性方程,成为一种数据驱动的翼型边界层转捩预测新方法,称为DMD/eN方法.在原有方法的基础上,改进了DMD网格线生成方法和扰动放大N因子的积分策略,并将RANS求解器与改进的DMD/eN方法进行耦合,实现了翼型定常绕流转捩预测自动化.采用该方法对LSC72613跨声速自然层流翼型以及NLF0416低速自然层流翼型在不同攻角下的绕流进行转捩预测,转捩点计算结果均与实验值和LST/eN方法吻合良好.该方法计算得到的N值增长曲线与LST/eN方法的包络线也较为吻合,进一步验证了积分策略的正确性.改进的DMD/eN方法可作为自然层流翼型设计的新的有力工具. 相似文献
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翼型前缘分离流动在等离子体激励器控制下的响应 总被引:1,自引:0,他引:1
将等离子体对中性气体的作用模型化为彻体力矢量,采用DES(Detached Eddy Simulation)和DDES(Delayed-Detached Eddy Simulation)方法,求解带彻体力源项的Navier-Stokes方程,研究NACA0015翼型16°迎角下,前缘分离流动在等离子体激励器控制下的响应过程.激励器工作后,DDES计算结果显示,分离流动经历一个渐近的再附过程;DES计算因发生网格诱导分离,得到了非定常的响应过程. 相似文献
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Glow discharge plasma on a solid surface will result in a body force which modifies the pressure distribution along the flow
boundary layer, and consequently re-attaches the separated flows for reduction of a hydrodynamic drag force. In this paper,
we investigate the discharge performance of various plasma-actuated electrodes in terms of their arrangements and structures.
The resulting optimal configuration for the electrode separation distance was used to develop a flexible actuated panel to
be mounted onto a NACA 0015 airfoil. Both uniphase and eight-phase power inputs were used to examine its drag reduction performance
at various attack angles and flow velocities. Numerical calculations were also performed by including an electrostatic body
force in the hydrodynamic equation. Good agreement were found between the numerical and experiment results. 相似文献
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讨论了常压均匀辉光放电等离子体的形成和杀菌机理,提出了等离子体杀菌技术,并通过实例介绍了常压均匀辉光放电等离子体在空气过滤杀菌中的效果和实际使用价值。 相似文献
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In this paper, a fully developed laminar flow in a porous channel between two paralleled flat plates in the presence of a double layer electric field is analyzed. The linear Poisson-Boltzmann equation is suggested to model the double layer electric field near the solid-liquid interface. The equation of motion is extended by including the electrical body force generating from the double layer field and then solved analytically. Different from previous models, our proposed one is continuous in the whole flow field and matches commonly-accepted models in the field of fluid mechanics. Besides, the effects of various physical parameters such as the zeta potential, the electrokinetic separation distance, and the ratio of the streaming current to conduction current on the velocity, the pressure, the apparent viscosity of the fluid, as well as the streaming potential are discussed. Physical explanations on the changing trends of those physical quantities with various parameters are given. 相似文献
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In this paper we report on an experimental study of the characteristics of nanosecond pulsed discharge plasma aerodynamic actuation. The N 2 (C 3 Π u ) rotational and vibrational temperatures are around 430 K and 0.24 eV, respectively. The emission intensity ratio between the first negative system and the second positive system of N 2 , as a rough indicator of the temporally and spatially averaged electron energy, has a minor dependence on applied voltage amplitude. The induced flow direction is not parallel, but vertical to the dielectric layer surface, as shown by measurements of body force, velocity, and vorticity. Nanosecond discharge plasma aerodynamic actuation is effective in airfoil flow separation control at freestream speeds up to 100 m/s. 相似文献
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In this paper, a fully developed laminar flow in a porous channel between two paralleled flat plates in the presence of a double layer electric field is analyzed. The linear Poisson-Boltzmann equation is suggested to model the double layer electric field near the solid-liquid interface. The equation of motion is extended by including the electrical body force generating from the double layer field and then solved analytically. Different from previous models, our proposed one is continuous in the whole flow field and matches commonly-accepted models in the field of fluid mechanics.Besides, the effects of various physical parameters such as the zeta potential, the electrokinetic separation distance, and the ratio of the streaming current to conduction current on the velocity, the pressure, the apparent viscosity of the fluid,as well as the streaming potential are discussed. Physical explanations on the changing trends of those physical quantities with various parameters are given. 相似文献
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Kelly-Wintenberg K. Sherman D.M. Tsai P.P.-Y. Gadri R.B. Karakaya F. Zhiyu Chen Roth J.R. Montie T.C. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2000,28(1):64-71
Two characteristics of microorganisms-extremely small size (0.01 to a few micrometers) and the ability to reproduce-hinder the effective filtration of bacteria and viruses from indoor air. The microorganisms captured by a filter in spite of their small size can reproduce in situ and be released into the airstream, giving rise to the “sick building syndrome”. The application of the One Atmosphere Uniform Glow Discharge Plasma (OAUGDP) to a filter can address both these issues. At University of Tennessee at Knoxville, we have recently developed the “Volfilter”, a planar version of the OAUGDP produced by attaching strip electrodes to both sides of a sheet of dielectric filter material and energizing the electrodes with a high-voltage, low-frequency RF source. After the filter material removes microorganisms from the airstream, the OAUGD plasma kills the captured microorganisms. The combination of an appropriate filter material and periodic application of the OAUGDP results in an effective capture and sterilization device even for the smallest microorganisms and requires minimum maintenance. This paper will describe results obtained during the operation of a laboratory-scale “Volfilter” challenged by two kinds of microorganisms, S. aureus and the bacterial virus Phi X 174. An objective of this work is to demonstrate that a “Volfilter” exposed to a OAUGDP will have the number of captured microorganisms on its surface reduced by a factor of one million 相似文献
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S. A. Isaev P. A. Baranov M. Yu. Smurov A. G. Sudakov A. V. Shebelev 《Thermophysics and Aeromechanics》2016,23(5):639-643
In the vicinity of a semicircular airfoil with slot suction of air provided with a 0.2-diameter (chord) vortex cell installed on the backside of the wing, at low speeds and zero angle of attack the pattern of the unsteady separated air-flow undergoes substantial changes, those changes being accompanied with the displacement of flow separation point toward the trailing edge. The slot suction of air and its blowout into the near wake in such an airfoil is organized using a discharge channel with a fan; from this channel, the air jet is discharged into atmosphere tangentially to the airfoil base, with the pressure drop in the fan being equal to twice the pressure head. Under such conditions, the integral force characteristics of the wing show dramatic changes: the lift force, initially being ultra-low negative, becomes positive, and the drag decreases two-fold. The static pressure decreases by two or three times on the upper arch of the profile, and it increases by two times on the lower part of the airfoil, the level of pressure pulsations decreasing by more than ten times. 相似文献
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We propose a simple moiré method of visualizing electromagnetic force lines. The indicial equation is first derived for the tangent (or normal) curve to the electric field (or magnetic induction) around two parallel-line charges (or currents). The derived equation is then shown to have a one-to-one correspondence with that of the moiré fringe formed by two overlapped radial gratings. Since the tangent (or normal) curve to the electric field (or the magnetic induction) corresponds to the direction of the electric (or magnetic) force on a test charge (or current), the radial grating moirés can be used for the visualization of electric (or magnetic) force lines. 相似文献