发表机构
University of California, Davis（加州大学戴维斯分校）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究提出无需拟合常数的可压缩有限弦方法，预测穿孔和多孔前缘的降噪效果，通过瑞利电导及修正计算导纳，实验验证误差低至2.5分贝，并揭示穿孔几何主要通过低频导纳组起作用。
AI 中文摘要
多孔和穿孔前缘可降低湍流相互作用噪声，但以往的降噪预测依赖于根据声学数据调整的材料阻抗。本文去除了这一调整。在可压缩亚声速流动中，针对任意弦向导纳求解了有限弦散射问题，其中包含了脱落尾迹、库塔条件和依赖于渗透性的边缘奇异性，并通过有限展长和阵列孔径表示闭合到远场。穿孔插入件的导纳由单个孔径的瑞利电导推导得出，并包含三项计算修正：板厚、相邻孔径间的相互作用，以及基于边界层孔径平均速度评估的豪氏掠流阻塞效应。体多孔插入件由其测量的渗透率和孔隙流体惯性表示。对于三种穿孔板在四种流动条件下的预测，与测量结果在84次比较中均方根误差为2.5分贝，而使用先前未缩放的阻抗时为4.4分贝。尽管马赫数为0.05，弦在声学上非紧凑，且不可压缩解在测量下降处上升。三种体多孔插入件中有两种在相互作用噪声主导时预测误差在1.7分贝均方根以内。穿孔板上测得的窄且等间距峰值未被任何测试导纳复现；其间距暗示源以自由流速度的0.62倍对流，这在冻结阵风模型中不存在。参数研究表明，穿孔几何几乎完全通过一个低频导纳组起作用，在该组中，对于埋入层流边界层内的孔，孔径半径的影响相互抵消。
英文摘要
Porous and perforated leading edges reduce turbulence-interaction noise, but predictions of the reduction have relied on material impedances adjusted to the acoustic data. This paper removes that adjustment. The finite-chord scattering problem is solved in compressible subsonic flow for an arbitrary chordwise admittance, with the shed wake, the Kutta condition and permeability-dependent edge singularities, and closed to the far field with the finite span and the array aperture represented. The admittance of a perforated insert is derived from the Rayleigh conductivity of one aperture with three computed corrections: plate thickness, interaction between neighbouring apertures, and Howe's grazing-flow blockage evaluated at the aperture-averaged velocity of the boundary layer. A bulk porous insert is represented by its measured permeability and pore-fluid inertia. For three perforates at four flow conditions the prediction agrees with measurements to 2.5 dB rms over 84 comparisons, against 4.4 dB with the unscaled impedance used previously. Although the Mach number is 0.05, the chord is acoustically non-compact, and an incompressible solution rises where the measurement falls. Two of three bulk porous inserts are predicted to within 1.7 dB rms where interaction noise dominates. Narrow, equally spaced peaks measured on perforated plates are reproduced by none of the admittances tested; their spacing implies a source convecting at 0.62 of the free-stream speed, absent from a frozen-gust model. A parameter study shows that the perforate geometry acts almost entirely through one low-frequency admittance group, in which the hole radius cancels for holes buried in the laminar boundary layer.
Comments41 pages, 8 figures. Submitted to Journal of Sound and Vibration (Special issue: Memorial for Roy K. Amiet)
