The noise sources of the tip-jet driven rotor are mainly classified as rotor blade noise and jet noise. The rotor blade noise includes thickness noise, loading noise, and nonlinear quadrupole noise, while the jet noise includes nozzle momentum noise and jet radiation noise. Each noise component has different noise source mechanisms related to flow characteristics and the rotating motion. Especially, the nozzle momentum noise has two noise source mechanisms based on the rotating steady aerodynamic load and the nozzle mass flow rate. The details of the time signal and spectrum are discussed to study the unique spectral characteristics. The tip-jet driven rotor noise has both tonal and broadband spectral characteristics. The periodicity of each instance of jet radiation noise is discussed, while the total jet radiation noise also has a tonal noise component. The noise source mechanisms and spectral characteristics are important considerations for an acoustically efficient tip-jet driven rotor.

中文翻译：

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Tip-Jet 驱动转子的噪声源和光谱特性

叶尖喷气驱动转子的噪声源主要分为转子叶片噪声和喷气噪声。转子叶片噪声包括厚度噪声、载荷噪声和非线性四极噪声，而射流噪声包括喷管动量噪声和射流辐射噪声。每个噪声分量都有与流动特性和旋转运动相关的不同噪声源机制。特别是喷管动量噪声具有基于旋转稳态气动载荷和喷管质量流量两种噪声源机制。讨论时间信号和频谱的细节以研究独特的频谱特性。尖端喷射驱动的转子噪声具有音调和宽带频谱特征。讨论了每个射流辐射噪声实例的周期性，而总射流辐射噪声也有音调噪声分量。噪声源机制和频谱特性是声学高效的尖端喷射驱动转子的重要考虑因素。