Ismaeel Zaman , Michele Falsi , Bin Zang , Mahdi Azarpeyvand , Roberto Camussi
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引用次数: 0
Abstract
The Boundary Layer Ingestion (BLI) configuration is a promising installed propulsion arrangement for aircraft owing to its potential to boost aerodynamic efficiency. However, it is prone to generate additional noise as the inflow to the propulsion system is non-uniform and turbulent due to the ingested boundary layer. Nevertheless, the acoustic characteristics of the BLI configuration and its sensitivity to different operating parameters (e.g., boundary layer thickness, turbulence contents and propeller rotational speeds) are not well understood. Thus, the present study reports a detailed experimental campaign to investigate the aerodynamic thrust, far-field acoustics and plate surface pressure of a two-bladed propeller ingesting distinct turbulent boundary layers (TBL) for a range of advance ratios. All results were compared against a reference ‘No BLI’ case. It was found that BLI noise comprises mostly broadband noise that is directed predominantly in the downstream direction parallel to the plate, whilst orthogonal to the plate, the noise signature is mostly tonal. When increasing thrust, the effect of BLI on noise is reduced. Scaling of the acoustic spectra with tip Mach number identifies that leading-edge-turbulence interaction was the main source of broadband noise in the BLI configuration and more importantly, showed two distinct operating regimes based on thrust conditions. Lastly, phase-averaged acoustic results showed marked noise variations over a rotation with an increase when the propeller begins to ingest the boundary layer, particularly for the thicker and more turbulent boundary layer, indicating that the broadband components became dominant during TBL interaction and were partly responsible for the modulation of the emitted noise.
由于具有提高气动效率的潜力,边界层摄入(BLI)配置是一种很有前途的飞机装机推进布置。然而,由于边界层摄入的缘故,推进系统的流入是不均匀和湍流的,因此容易产生额外的噪声。然而,人们对 BLI 配置的声学特性及其对不同运行参数(如边界层厚度、湍流含量和螺旋桨转速)的敏感性还不甚了解。因此,本研究报告了一项详细的实验活动,以研究双叶螺旋桨的气动推力、远场声学和板面压力,该螺旋桨摄入了一系列推进比的不同湍流边界层(TBL)。所有结果都与参考的 "无 BLI "情况进行了比较。结果发现,BLI 噪音主要由宽带噪音组成,这些噪音主要指向平行于板面的下游方向,而与板面正交的噪音特征主要是音调。当推力增大时,BLI 对噪声的影响减小。声学频谱与尖端马赫数的比例确定了前缘-湍流相互作用是 BLI 配置中宽带噪声的主要来源,更重要的是,根据推力条件显示了两种不同的工作状态。最后,相位平均声学结果表明,当螺旋桨开始摄入边界层时,噪声在旋转过程中会发生明显变化,尤其是在较厚和较湍动的边界层中,这表明宽带成分在 TBL 相互作用过程中变得占主导地位,并且是发射噪声调制的部分原因。
期刊介绍:
The Journal of Sound and Vibration (JSV) is an independent journal devoted to the prompt publication of original papers, both theoretical and experimental, that provide new information on any aspect of sound or vibration. There is an emphasis on fundamental work that has potential for practical application.
JSV was founded and operates on the premise that the subject of sound and vibration requires a journal that publishes papers of a high technical standard across the various subdisciplines, thus facilitating awareness of techniques and discoveries in one area that may be applicable in others.