The wall pressure fluctuations induced by turbulent boundary layers on a flat plate model were measured with an L-shaped array of Kulite miniature pressure sensors. By installing a NACA airfoil above the plate with an adjustable angle of attack, different adverse pressure gradients were produced on the plate. The streamwise and spanwise coherence and coherence lengths of the wall pressure fluctuations are calculated for zero and adverse pressure gradient flows. The effect of the pressure gradient on the coherence and coherence lengths in both streamwise and spanwise directions is quantified. Based on the results of the present test cases and selected published datasets in zero pressure gradients, covering the range of Reynolds numbers based on the momentum thickness between 3300 and 42000, the Reynolds number dependence of the streamwise wall pressure coherence is discussed and mathematically expressed. A coherence length model for zero pressure gradient boundary layers, taking into account the Reynolds number effect, is proposed based on scaled spectra of the coherence lengths. In comparison with the other published models, the present model achieves a considerable improvement of the prediction accuracy for boundary layer flows, covering a large range of Reynolds numbers. Furthermore, an evaluation of the Corcos model and the Smol’yakov and Tkachenko model for prediction of the off-axis coherence of the fluctuating wall pressure field is made.

平板模型上湍流边界层引起的壁面压力波动是用 L 形的 Kulite 微型压力传感器阵列测量的。通过在板上方安装具有可调攻角的 NACA 翼型，可以在板上产生不同的不利压力梯度。计算零压力梯度流和逆压力梯度流的壁面压力波动的流向和展向相干和相干长度。压力梯度对流向和展向方向上的相干和相干长度的影响被量化。基于当前测试案例的结果和选定的零压力梯度已发布数据集，涵盖了基于 3300 和 42000 之间的动量厚度的雷诺数范围，讨论了流向壁压力相干性的雷诺数相关性，并用数学方法表示。基于相干长度的缩放谱，提出了考虑雷诺数效应的零压力梯度边界层的相干长度模型。与其他已发表的模型相比，本模型实现了边界层流预测精度的显着提高，涵盖了大范围的雷诺数。此外，还对 Corcos 模型和 Smol'yakov 和 Tkachenko 模型进行了评估，用于预测壁面压力场波动的离轴相干性。是基于相干长度的缩放谱提出的。与其他已发表的模型相比，本模型实现了边界层流预测精度的显着提高，涵盖了大范围的雷诺数。此外，还对 Corcos 模型和 Smol'yakov 和 Tkachenko 模型进行了评估，用于预测壁面压力场波动的离轴相干性。是基于相干长度的缩放谱提出的。与其他已发表的模型相比，本模型实现了边界层流预测精度的显着提高，涵盖了大范围的雷诺数。此外，还对 Corcos 模型和 Smol'yakov 和 Tkachenko 模型进行了评估，用于预测壁面压力场波动的离轴相干性。