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中文核心期刊

MHD控制超声速边界层的理论研究和数值分析

Physics and numerical simulations of mhd acceletrated supersonic boundary layer

  • 摘要: 对MHD(mechanisms of magnetohy drodynamics)控制超声速平板湍流边界层的机理进行了理论研究和数值模拟. 理论上,采用等离子体低频近似碰撞频率模型,建立等离子体中电子和离子的力平衡方程,得到等离子体速度、极化电场以及边界层速度. 数值上,通过空间HLLE格式、LU--SGS时间推进求解时均磁流体动力学湍流方程,其中湍流模型采用sst--k\omega双方程模型. 研究结果表明:(1)边界层速度的理论结果和数值结果误差在7%范围内;(2)只有磁场而电场为零时,洛仑兹力起到减小摩阻的作用. 施加电场后,洛仑兹力能够加速边界层低速区流体;(3) 在边界层外层,越靠近壁面,作用参数越小;而在边界层近壁区黏性底层,虽然惯性力减小, 但黏性力却迅速增加,因此越靠近壁面,作用参数反而越大,加速低速流的代价增加.

     

    Abstract: The mechanism of magnetohydrodynamics (MHD) controlling onsupersonic flat-plate turbulent boundary layer was explored in theory andnumerical simulation. The collision frequencies between theelectron-molecules and ion-molecules at the boundary layer were obtained bylow frequency approximation in the plasma, and the force balances forelectrons and ions were set up to solve the plasma velocities, polarizationelectric field and the boundary layer velocities. HLLE schemes and LU-SGSmethod were used to numerically solve the sst-k\omega turbulent model.The results show that, (1) the relative error between numerical results andtheoretic results are in the range of 7%; (2) in the absence of electricfield, the Lorentz force can decrease the skin friction. With an externalelectric field applied, the low velocity fluid in the boundary layer can beaccelerated; (3) in the outer layer of boundary layer, the interactionparameter decreases with the distance to the wall, but in the inner layer asthe viscous force dominates the flow, the interaction parameter increaseswith the distance to the wall.

     

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