Slat Noise Trend Predictions Using CAA With Stochastic Sound Sources From A Random Particle-Mesh Method (RPM)

Slat Noise Trend Predictions Using CAA With Stochastic Sound Sources From A Random Particle-Mesh Method (RPM)
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使用 CAA 和来自随机粒子网格方法 (RPM) 的随机声源进行板条噪声趋势预测

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发表时间：
2006
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通讯作者：
R. Ewert
R. Ewert
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作者：
R. Ewert

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对高升力翼型进行缝翼噪声模拟。的 高升力翼型几何形状是二元缝翼翼型 无需部署襟翼的配置，以避免额外的 声源位于襟翼处。采用低成本 CAA 方法， 基于时域中的声学微扰方程 (APE) 这是由随机声源强制的。随机模型 于 AIAA 2005-2862 中引入，基于空间 白噪声与滤波器内核的卷积并且可以再现 湍流动能和长度尺度的目标分布， 例如，由湍流的稳定 RANS 计算提供 问题。宽带板条噪声的马赫数标度定律 组件基于三种不同的自由流进行评估 速度（M=0.088、0.118、0.165）。随机能力 重现目标湍流动能拓扑的方法是 研究过。模型参数变化对质量的影响 再现的湍流动能分布及其效果 对预测的远场频谱进行评估。只有一个小 发现了模型参数的依赖性。板条间隙的影响 研究了三种情况下宽带声远场的变化 不同的板条配置，除了参考之外还包括 板条位置 一种配置是减小的，一种配置是增加的 板条间隙。先前在完整三元素上的实验结果 高升力翼型表明缝翼间隙的有效依赖性 声学远场宽度通常减少 5dB 由于速度降低，板条间隙减少约 15\% 约25\%。目前的研究调查了这种影响 二元高升力配置。
Slat Noise simulations are carried out for a high-lift airfoil. The high-lift airfoil geometry is a two-element slat-airfoil configuration without deployed flap in order to avoid additional sound sources at the flap. A low-cost CAA approach is applied, which is based on acoustic perturbation equations (APE) in the time-domain that are forced by stochastic sound sources. The stochastic model was introduced in AIAA 2005-2862 and is based on the spatial convolution of white-noise with a filter kernel and can reproduce target distributions of turbulent kinetic energy and length scales, e.g., provided by a steady RANS computation of the turbulent flow problem. The Mach number scaling law of the broadband slat noise component is evaluated based on three different freestream velocities (M=0.088, 0.118, 0.165). The capability of the stochastic method to reproduce a target turbulence kinetic energy topology is studied. The effect of model parameter variations on the quality of the reproduced turbulent kinetic energy distribution and its effect on the predicted far-field spectrum is evaluated. Only a small dependence on the model parameter is found. The effect of slat gap variation on the broadband acoustic far-field is studied for three different slat configurations, which encompass beside the reference slat position one configuration with reduced, and one with increased slat gap. Previous experimental findings at a full three-element high-lift airfoil indicated an effective dependence of the slat gap width on the acoustic far-field with typically 5dB reduction for a slat gap reduction of about 15\% due to a decrease of the velocity of about 25\%. The current study investigates this effect for the two-element high-lift configuration.