Fundamental Study on Flow Characteristics of Synthetic Jets for Development of Blown Flap

射流已被应用于控制流动分离的各个领域。在过去的十年里，有几项研究对合成射流进行了调查。然而，仍有许多需要澄清，包括合成射流的结构和康达效应的细节。本文通过实验和数值模拟，阐明了自由合成射流和刚性边界附近合成射流的一些基本流动特性。主要结果是，自由合成射流的速度分布取决于K=Re/S^2（雷诺数与斯托克斯数的平方之比），并可通过中心线处的最大速度和射流半宽度来识别。应用烟线法实现了流场的可视化。此外，还证实了合成射流在刚性边界附近的流动特性和合成射流的再附着长度除了由归一化阶跃高度H_1/b_0决定外，还与K有关。

The jet flows have been applied to various fields to control the flow separation. Over the last decade, several studies have investigated synthetic jets. However, there are still many clarifications needed, including details of the structure and Coanda effect of synthetic jets. The present study clarifies some fundamental flow characteristics of free synthetic jets and synthetic jets near a rigid boundary by conducting an experiment and numerical simulations. As the main results, it is found that the velocity distribution of free synthetic jets depends on K=Re/S^2(the ratio of the Reynolds number to the square of the Stokes number) and can be identified by the maximum velocity at the centerline and the jet half-width. Flow visualization is carried out applying the smoke wire method. In addition, it is confirmed that the flow characteristics of the synthetic jet near a rigid boundary and re-attachment length of the synthetic jet are determined not only by H_1/b_0(normalized step heights) but also K.