Abstract A method for the experimental characterization of the velocity, hydrodynamic pressure, and acoustic generation in a subsonic ( Re H = 25 , 500 ), three-dimensional, turbulent wall jet is presented. An acoustic analogy formulated for the turbulent wall jet shows that the far-field acoustics relate to the Reynolds stress fluctuations of the velocity field or the product of the hydrodynamic pressure fluctuations and the rate-of-strain field. As these quantities cannot be measured directly with sufficient resolution, low-order reconstructions of the velocity field based on the use of the Proper Orthogonal Decomposition and Stochastic Estimation are developed. Reconstruction of the three-dimensional field is accomplished using spanwise-aligned, stereoscopic particle image velocimetry measurements, obtained at 16 streamwise locations synchronously with an array of 32 surface pressure transducers. The velocity field reconstruction is then used to calculate the fluctuating pressure field (via Poisson’s equation) allowing for the evaluation of coupled pressure-velocity terms in addition to an acoustic analogy for the acoustic far-field. Application of these methods show that the large-scale motion throughout the shear layer is captured by the velocity and hydrodynamic pressure field estimates and features of the acoustic far-field are recovered.

中文翻译：

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三维湍流壁射流的速度、流体动压和声辐射的低阶估计

摘要 提出了一种用于对亚音速 (Re H = 25 , 500 ) 三维湍流壁射流中的速度、流体动压和声发生进行实验表征的方法。为湍流壁射流制定的声学类比表明，远场声学与速度场的雷诺应力波动或流体动压波动与应变率场的乘积有关。由于无法以足够的分辨率直接测量这些量，因此开发了基于使用适当正交分解和随机估计的速度场的低阶重建。三维场的重建是使用展向对齐的立体粒子图像测速测量完成的，与 32 个表面压力传感器阵列在 16 个流向位置同步获得。然后使用速度场重建来计算波动压力场（通过泊松方程），除了对声学远场进行声学类比之外，还允许评估耦合压力-速度项。这些方法的应用表明，通过速度和流体动压场估计捕获了整个剪切层的大规模运动，并恢复了声学远场的特征。