Prediction and Control of University Separation

流动分离的控制一直是一个重要而有趣的现象。近年来，由于越来越多的工业对流动性能提出了更高的要求，它越来越受到重视。本文对俯仰型和平动型等运动翼型的流场进行了深入的研究。然而，通过详细的测量得到的结果很少，特别是在低雷诺数区域。分离预测的研究才刚刚开始，分离控制技术尚未见报道。对运动翼型的非定常分离问题进行了大量的数值和实验研究。然而，它们大多是在高雷诺数区域进行的。由于运动翼型周围发生的现象非常复杂，非定常分离问题仍然存在许多尚未解决的问题。考虑到利用运动翼型进行分离控制，大尺寸翼型对机械结构的强度要求高，功率要求大，是不现实的。因此，它是理想的分离控制使用一个小的翼型。此外，低雷诺数区分离控制的研究也成为微机电系统（MEMS）研究的热点。本文通过流动显示和非定常流动力测量，阐明了俯仰翼型周围非定常分离的机理和作用在低雷诺数区域的非定常流动力特性。

The control of the flow separation has been important and interesting phenomenon. Recently, it has been more and more important because higher performance of flow has been demanded in a wide range of industry. The flow field around moving airfoils, such as pitching and translating airfoils, has been investigated energetically. However, few results were obtained by detailed measurements, especially at low Reynolds number region. The study of prediction of separation has begun to carry out and the technique of separation control has not been reported yet.Many studies on unsteady separation around a moving airfoil have been carried out in the numerical and experimental studies. However, most of them have been performed at high Reynolds number region. The many unsolved problems on unsteady separation still remain because the phenomenon occurring around moving airfoils is very complicated. Considering separation control by using a moving airfoil, a large-sized airfoil is not practical because it needs the strong and big mechanical structure and high power. As a result, it is desirable for the separation control to use a small airfoil. Moreover, the study on separation control at low Reynolds number region attracts much attention by researchers developing the micro-electro-mechanical-systems (MEMS).In this study, the mechanism of unsteady separation around pitching airfoils and the characteristics of unsteady fluid forces acting on them at low Reynolds number region have been clarified by the flow visualization and the unsteady fluid forces measurement.