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Numerical Study fof New Control Method fir Cavity Flow Oscillations

腔流振荡新控制方法的数值研究

基本信息

批准号：
18560160
负责人：
YOSHIDA Takashi
金额：
$ 1.46万
依托单位：
Shinshu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

项目摘要

We investigated the active control of self-sustained oscillating flow over an open cavity using a moving bottom wall. The incompressible Navier-Stokes equations were solved using finite difference methods for the two-dimensional cavity with laminar boundary layer upstream.We move the cavity bottom wall tangentially with nondimensional velocities ranging from -0.2to +0.2for the cavity aspect ratio L/D=2.0. The results shown that wall velocity changes the characteristics of recirculating flow in the cavity and that the modification of recirculating flow plays an important role in changing the oscillation characteristics of the separated shear layer. When the wall velocity is less than -0.1, two recirculating vortices change to one clockwise recirculating vortex in the cavity, so that the self-excited shear layer oscillations are completely suppressed. When the wall velocity is more than +0.19, two stationary vortices exist on the upper side and lower side of the cavity and the self-excited shear layer oscillations are suppressed.A series of computations are carried out for different cavity lengths. The cavity length is varied at 0.1 intervals, ranging from 1.0 up to 4.0. For small cavity length, L<1.6, the flow does not oscillate and only one recirculation vortex is present in the cavity. For 1.7 < L < 3.0, the shear layer oscillates in mode II with two or three recirculation vortices. For long cavities L >3.1, four vortices appear inside the cavity and the oscillation mode switches from mode II to mode III.The results of controlled simulations show that the self-sustained shear layer oscillations for several cavity aspect ratio and different oscillation modes are suppressed by our control method using moving bottom wall.

我们研究了使用移动底壁对开放腔体上自持振荡流的主动控制。采用有限差分法求解上游具有层流边界层的二维空腔的不可压缩Navier-Stokes方程。对于空腔纵横比L/D=2.0，我们以-0.2到+0.2的无量纲速度切向移动空腔底壁。结果表明，壁速改变了腔内循环流的特性，循环流的修改对于改变分离剪切层的振荡特性起着重要作用。当壁速小于-0.1时，腔内由两个循环涡变为一个顺时针循环涡，自激剪切层振荡被完全抑制。当壁速大于+0.19时,空腔上下两侧存在两个静止涡,自激剪切层振荡得到抑制。针对不同的空腔长度进行了一系列计算。空腔长度以 0.1 为间隔变化，范围从 1.0 到 4.0。对于较小的腔体长度，L<1.6，流动不会振荡，并且腔体中仅存在一个再循环涡流。当 1.7 < L < 3.0 时，剪切层以模式 II 振荡，具有两个或三个再循环涡流。对于长腔L>3.1，腔内出现四个涡流，振荡模式从模式II切换到模式III。控制模拟的结果表明，我们使用移动底壁的控制方法抑制了多种腔长宽比和不同振荡模式的自持剪切层振荡。