Jet-Surface Interaction Test: Far-Field Noise Results
Jet-Surface Interaction Test: Far-Field Noise Results
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DOI：
10.1115/gt2012-69639
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发表时间：
2012-06
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影响因子：
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通讯作者：
Clifford A. Brown
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作者：
Clifford A. Brown
为下一代飞机提出的许多配置依靠机翼或其他飞机表面来屏蔽地面观察者的发动机噪音。然而，目前预测屏蔽效应以及高速射流与硬表面相互作用产生的任何新噪声源的能力有限。此外，来自适合开发和验证噪声预测方法的表面附近的喷气机的高质量实验数据通常与特定的车辆概念相关，因此非常复杂。射流/表面相互作用测试旨在为开发飞机噪声预测工具的研究人员提供涵盖广泛的表面几何形状和位置以及射流的高质量数据集。第一阶段的目标是测量简单平面附近的喷射噪声，同时改变表面长度和位置，以便：(1) 当表面仅充当喷射噪声屏蔽以及喷射/表面相互作用产生额外噪声时验证噪声预测方案，以及 (2) 确定感兴趣区域，以便在第二阶段进行更详细的测试。为了满足这些第一阶段的目标，以两种不同的配置将平板安装在两轴横梁上：（1）作为喷射器和观察者（麦克风阵列）之间的屏蔽，（2）作为喷射器与观察者相反一侧的反射表面。表面移动通过轴向位置 2 ≤ xTE/Dj ≤ 20（在表面后缘处测量，xTE，并通过射流直径 Dj 归一化）和径向位置 1 ≤ h/Dj ≤ 20。使用两个喷嘴在轴向和径向表面位置的每种组合以及跨几种流态（亚音速冷、亚音速热、欠膨胀、理想膨胀、和过度膨胀的超音速冷）。这里讨论的远场噪声结果显示了表面屏蔽部分喷射噪声的位置，并且根据表面和观察者的位置，当表面向下游延伸并接近喷射羽流时，在何处产生擦洗和后缘噪声源。
Many configurations proposed for the next generation of aircraft rely on the wing or other aircraft surfaces to shield the engine noise from the observers on the ground. However, the ability to predict the shielding effect and any new noise sources that arise from the high-speed jet flow interacting with a hard surface is currently limited. Furthermore, quality experimental data from jets with surfaces nearby suitable for developing and validating noise prediction methods are usually tied to a particular vehicle concept and, therefore, very complicated. The Jet/Surface Interaction Test was intended to supply a high quality set of data covering a wide range of surface geometries and positions and jet flows to researchers developing aircraft noise prediction tools. During phase one, the goal was to measure the noise of a jet near a simple planar surface while varying the surface length and location in order to: (1) validate noise prediction schemes when the surface is acting only as a jet noise shield and when the jet/surface interaction is creating additional noise, and (2) determine regions of interest for more detailed tests in phase two. To meet these phase one objectives, a flat plate was mounted on a two-axis traverse in two distinct configurations: (1) as a shield between the jet and the observer (microphone array) and (2) as a reflecting surface on the opposite side of the jet from the observer. The surface was moved through axial positions 2 ≤ xTE/Dj ≤ 20 (measured at the surface trailing edge, xTE, and normalized by the jet diameter, Dj) and radial positions 1 ≤ h/Dj ≤ 20. Far-field and phased array noise data were acquired at each combination of axial and radial surface location using two nozzles and at 8 different jet exit conditions across several flow regimes (subsonic cold, subsonic hot, underexpanded, ideally expanded, and overexpanded supersonic cold). The far-field noise results, discussed here, show where the surface shields some of the jet noise and, depending on the location of the surface and the observer, where scrubbing and trailing edge noise sources are created as a surface extends downstream and approaches the jet plume.