ABSTRACT

In this study, a new vortex-based fluidic oscillator was designed whose performance was numerically evaluated by solving the URANS equations. The oscillator consists of a primary chamber and secondary chamber, separated by a mid-throat and connected by two feedback channels. The jet passing through these chambers forms two pairs of vortices inside the primary and secondary chambers. These vortices roll onto the jet shear layer, and gradually disturbs the jet symmetry. As a result, the vortices grow and shrink asymmetrically, activating the feedback flow to make a harmonic oscillation. The collision of the oscillating jet with the mid-throat traps a part of the jet shear layer in the primary chamber, which forms a strong vortex, returning the jet toward the other side of the mid-throat. The vortex inside the secondary chamber causes the jet to attach to one side of the secondary chamber, deviating the outlet jet to the other side. To compare the performance of the new oscillator with the original one, URANS equations were solved for two-dimensional models of both oscillators with the same grid generation and boundary conditions. The new oscillator had a higher oscillation frequency, a lower pressure drop, and a higher output momentum flux.

摘要

在这项研究中，设计了一种新的基于涡流的流体振荡器，其性能通过求解URANS方程进行了数值评估。振荡器由一个主腔和一个副腔组成，中间腔被喉咙隔开，并通过两个反馈通道相连。穿过这些腔室的射流在主要腔室和次要腔室内形成两对涡旋。这些涡流滚动到射流剪切层上，并逐渐扰乱射流对称性。结果，涡旋不对称地生长和收缩，激活了反馈流以产生谐波振荡。振荡射流与喉中部的碰撞将射流剪切层的一部分捕获在主腔室中，形成了强烈的旋涡，使射流返回喉中部的另一侧。二级腔室内的涡流使射流附着到二级腔的一侧，使出口射流偏向另一侧。为了将新振荡器与原始振荡器的性能进行比较，针对具有相同网格生成和边界条件的两个振荡器的二维模型，求解了URANS方程。新的振荡器具有更高的振荡频率，更低的压降和更高的输出动量通量。