Abstract A fluidic oscillator can produce self-induced and self-sustaining oscillating jet by fluid supply without moving parts. This device has attracted research interest in heat and mass transfer enhancement in recent years. In the current study, a double-feedback fluidic oscillator was numerically investigated based on three-dimensional unsteady Reynolds-averaged Navier-Stokes equations (3D-URANS) while the operating fluid is an incompressible flow. Then, the results were validated with experimental data by two-dimensional time-resolved particle image velocimetry (2D-TR-PIV) and thermographic phosphor thermometry (TPT) for the velocity and temperature field, respectively. A grid sensitivity study was done by comparison of instantaneous and time-averaged flow fields. Additionally, the proper orthogonal decomposition (POD) method was used to find the phase information of the oscillating jet, and fast Fourier transform (FFT) analysis was used to find the frequency of the oscillating jet to validate the numerical results. The effect of the working fluid was also studied. Finally, in order to determine the effect of the Reynolds number on heat transfer enhancement, the Q-criterion was calculated to provide detailed insight into the oscillating mechanism. The results show that the non-dimensional frequency of oscillation is independent of either the working fluid or mass flow rate. Additionally, for a given fluid, increasing Re causes strong vortices and increases the frequency of oscillation. However, the convection heat transfer did not change significantly when varying the mass flow rate because the convection velocity of vortices increases as the mass flow rate is enhanced. A comparison with a free jet reveals that the oscillating jet in a channel is useful in terms of covering a larger area.

中文翻译：

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通道内振荡射流流动特性与传热的实验与数值研究

摘要 流体振荡器可以通过流体供给产生自诱导和自持振荡射流，无需运动部件。近年来，该装置引起了对传热传质增强的研究兴趣。在当前的研究中，基于三维非定常雷诺平均纳维-斯托克斯方程 (3D-URANS) 对双反馈流体振荡器进行了数值研究，而工作流体是不可压缩的流动。然后，结果分别通过二维时间分辨粒子图像测速 (2D-TR-PIV) 和热成像磷光体测温 (TPT) 的速度和温度场的实验数据进行验证。通过比较瞬时和时间平均流场来进行网格敏感性研究。此外，采用适当的正交分解(POD)方法求出振荡射流的相位信息，利用快速傅立叶变换(FFT)分析求出振荡射流的频率，以验证数值结果。还研究了工作流体的影响。最后，为了确定雷诺数对传热增强的影响，计算了 Q 标准以提供对振荡机制的详细了解。结果表明，无量纲振荡频率与工作流体或质量流量无关。此外，对于给定的流体，增加 Re 会导致强烈的涡流并增加振荡频率。然而，当改变质量流量时，对流换热没有显着变化，因为涡流的对流速度随着质量流量的增加而增加。与自由射流的比较表明，就覆盖更大的区域而言，通道中的振荡射流是有用的。