Tonal noise suppression of an underexpanded orifice jet upon impingement over corrugated geometries

IF 1.9 4区工程技术 Q2 ACOUSTICS Journal of Vibration and Acoustics-Transactions of the Asme Pub Date : 2022-04-01 DOI:10.1115/1.4054254

D. Sarangi, Krishnamurthy Srinivasan

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引用次数: 1

Abstract

The current study investigates the noise generation of an orifice jet upon impingement over different corrugated geometries for different nozzle pressure ratios. Semi-circular corrugations of different pitch lengths are considered for this study. A comparison of corrugated geometries is made with the flat plate. A standoff distance of 3.5 times jet diameter is considered. Several tones and their harmonics of the feedback loops established between the orifice exit and the plates are analyzed. The far-field acoustic spectra show that the corrugated geometries emit less noise at subsonic speed compared to supersonic speed. A reduction of overall sound pressure level (OASPL) up to a range of 3 dB to 8 dB is observed for the corrugated plate compared to the base plate at the subsonic range. The tonal noise is reduced for the corrugated geometries at all NPRs. The wavelength of the primary tones is compared with the pitch length of semi-circular corrugations. This indicates that semi- circular corrugations reduce the wavelength of fundamental tones and increase the time required to complete the feedback loop. Schlieren images show the presence of the acoustic feedback loop and standing waves near the impingement region for the flat plate. The flow field in between the semi-circular corrugations is analyzed by solving the large eddy simulation. The directivity study shows a reduction in OASPL value at the upstream direction at NPR 4 and 4.8 for the corrugated geometries.

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欠膨胀孔射流在波纹几何形状上撞击时的音调噪声抑制

本文研究了在不同喷嘴压力比下，孔板射流在不同波纹几何形状上撞击时产生的噪声。本研究考虑了不同节距长度的半圆波纹。将波纹几何形状与平板进行比较。考虑距离为射流直径的3.5倍。分析了在孔板出口和板之间建立的反馈回路的几种音调及其谐波。远场声谱表明，与超音速相比，波纹几何形状在亚音速下发出的噪声更小。在亚音速范围内，与基板相比，波纹板的总声压级(OASPL)降低了3db至8db。音调噪声是减少了波纹几何形状在所有的npr。将基音的波长与半圆波纹的基音长度进行了比较。这表明，半圆形波纹减少了基本音调的波长，增加了完成反馈回路所需的时间。纹影图像显示在平板撞击区域附近存在声反馈回路和驻波。通过求解大涡模拟，分析了半圆波纹间的流场。指向性研究表明，在上游方向，波纹几何形状的OASPL值在NPR为4和4.8时有所降低。

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来源期刊

Journal of Vibration and Acoustics-Transactions of the Asme 工程技术-工程：机械

CiteScore

4.20

自引率

11.80%

发文量

审稿时长

7 months

期刊介绍： The Journal of Vibration and Acoustics is sponsored jointly by the Design Engineering and the Noise Control and Acoustics Divisions of ASME. The Journal is the premier international venue for publication of original research concerning mechanical vibration and sound. Our mission is to serve researchers and practitioners who seek cutting-edge theories and computational and experimental methods that advance these fields. Our published studies reveal how mechanical vibration and sound impact the design and performance of engineered devices and structures and how to control their negative influences. Vibration of continuous and discrete dynamical systems; Linear and nonlinear vibrations; Random vibrations; Wave propagation; Modal analysis; Mechanical signature analysis; Structural dynamics and control; Vibration energy harvesting; Vibration suppression; Vibration isolation; Passive and active damping; Machinery dynamics; Rotor dynamics; Acoustic emission; Noise control; Machinery noise; Structural acoustics; Fluid-structure interaction; Aeroelasticity; Flow-induced vibration and noise.