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A Study on the Active Control of Separation in a Diffuser by Vortex Generator Jets

涡流发生器射流扩压器分离主动控制研究

基本信息

批准号：
09650196
负责人：
NISHI Michihiro
金额：
$ 2.11万
依托单位：
KYUSHU INSTITUTE OF TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

This research project aims to establish all effective new control method of separation, which manages the critical performance of various fluid flow devices and machines, especially to develop an active control method that is used properly depending on the external condition. For this purpose, we have adopted a vortex generator jet method, which is to generate streamwise vortices by pitched and skewed jets issued from the wall, considering the feature that a jet has the high potential of adjustability. From the present basic research planned for a two-years program, we can have the following interesting results(1) Distribution of backflow-fraction is a useful measure to specify one of characteristics of separating (low in a diffuser. Here are proposed two kinds of the measurement methods, a X-type hot wire and a split film sensor. Usage of the latter will generally be regarded as convenient, if the measurement will be made using a smaller-size test-rig.(2) Although a streamwise vortex … More induced by a VGJ (vortex-generator-jet) is weaker than that by a 501i(I vortex generator, The row of streamwise vortices sufficiently applicable to control separation in a diffuser is observed in the boundary layer, providing that the velocity ratio of jet to freestream is around 2.(3) As for a typical example, the following VGJ is applicable to suppress the separation observed in a conical diffuser having the divergence angle of 18 deg and the exit-to-inlet area ratio of 2.56, and the pressure recovery coefficient is improved from 0.4 to 0.6 : Pitch-angle = 30 deg, Skew-angle = 90 deg, Jet-dia. = 0.048 D, The number-of-jets = 8, Velocity-ratio = 2.(4) The decay of a streamwise vortex in a two-dimensional channel is fairly predicted by the numerical analysis based on the Reynolds-Averaged Navier-Stokes equation with the standard k-epsilon turbulence model.(5)In the case of a downstream diffuser, it is effective to detect the magnitude of velocity fluctuation in a freestream at the diffuser inlet as the signal for the active control Less

该研究项目旨在建立所有有效的新型分离控制方法，管理各种流体流动装置和机器的关键性能，特别是开发一种根据外部条件正确使用的主动控制方法。为此，考虑到射流具有高度可调节潜力的特点，我们采用了涡流发生器射流方法，即通过从壁上发出的倾斜和倾斜的射流产生流向涡流。从目前计划的两年计划的基础研究中，我们可以得到以下有趣的结果（1）回流分数的分布是指定分离特性之一的有用度量（扩散器中的低）。这里提出两种测量方法，X型热线和分裂薄膜传感器。如果使用较小尺寸的测量，则通常认为后者的使用比较方便 (2) 虽然 VGJ (涡流发生器-射流) 引起的流向涡流比 501i(I 涡流发生器) 弱，但在边界层中观察到足以控制扩散器中分离的流向涡流，前提是射流与自由流的速度比约为 2。(3) 作为一个典型示例，以下 VGJ 适用于抑制发散角为 18 deg、出入口面积比为 2.56 的锥形扩压器中观察到的分离，压力恢复系数从 0.4 提高到 0.6：俯仰角 = 30 deg，倾斜角 = 90 deg，Jet-dia。 = 0.048 D，射流数量 = 8，速度比 = 2。(4) a 的衰减基于雷诺平均纳维-斯托克斯方程和标准k-epsilon湍流模型的数值分析可以很好地预测二维通道中的流向涡流。(5)在下游扩压器的情况下，检测扩压器入口处自由流的速度波动幅度作为主动控制信号是有效的。