Basic Study on Active-Feedback Control of Non-Linear Heat and Fluid Flow

为了寻求一种有效的热流主动反馈控制方法，对控制理论和控制装置进行了广泛的研究。本文将次优控制理论应用于以跨向虚拟体力场作为控制输入的数值模拟通道流动。与简单的反馈律相比，次优控制以较小的控制量实现了显著的湍流阻力减小。采用直接数值模拟的方法，测试了具有柔性壁面的湍流通道壁面变形的简单振荡模式。在平均流动特性和瞬时流动结构中观察到实质性的影响。发现湍流结构在增强和阻尼阶段都依赖于壁面变形的尺度。基于神经网络的最优控制算法对热传导和Burgers方程的控制是有效的。该方法还成功地应用于汽缸下游速度波动的管理。设计了一组由12组襟翼作动器组成的阵列，用于控制近壁准顺流旋涡结构的运动。发现作动器的周期运动对湍流统计量的影响选择性地影响了展向速度分量。利用光刻技术研制了电磁襟翼作动器样机。模型预测的皮瓣动态特性与实验结果吻合较好。在圆形喷嘴唇上安装一组襟翼可以有效地控制轴对称射流的旋涡脱落现象。通过一系列的DNS和室内实验，研究了壁面湍流中粒子的动力学。研究了颗粒对传热现象的影响。

In pursuit of an effective active feedback control methodology for heat and fluid flow, control theories and control devices were studied extensively. The following conclusions can be derived :A suboptimal control theory is applied to the numarically-simulated channel flow with a spanwise virtual body force field as a control input. The suboptimal control achieves a significant turbulent drag reduction with fairly small control, when compared with simple feedback law.A simple oscillatory mode of wall deformation is tested in a turbulent channel with a flexible wall by using direct numerical simulation. The substantial influences are observed in the mean flow properties as well as instantaneous flow structures. The turbulent structures are found to be dependent on the scales of the wall deformation at both their enhanced and damped phases.The optimal control algorithm based on neural network (NN) was found to be effective for controlling the heat conduction and the Burgers equations. The present method is also applied to the management of velocity fluctuations downstream of a cylinder successfully.An array of twelve sets of flap actuators was developed so as to control the kinematics of the near-wall quasi-streamwise vortical structures. The effect of periodic motion of the actuators on the turbulent statistics was found to affect the spanwise velocity component selectively.A prototype electromagnetic flap actuator was developed with photo lithography. The dynamic characteristics of the flap predicted by models were in reasonable agreement with experimental results. A group of flap mounted on the circular nozzle lip can manipulate significantly the vortex shedding phenomena of an axisymmetric jet.Dynamics of particles in wall turbulence was examined by using a series of DNS and laboratory experiments. The effect of particle on heat transfer phenomena was also studied.