Fan Noise Reduction by Cascade Clocking for Next Generation Supersonic Transport

通过级联时钟降低风扇噪音，实现下一代超音速运输

• 批准号: 12555272
• 负责人: KAJI Shojiro
• 金额: $ 8.58万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12555272/
• 关键词: Cascade Clocking; Rotor-Stator Interaction; Fan Tone Noise; Axial Compressor; Noise Reduction; Supersonic Transport; Blade Passing Frequency Tone; 超音速度輸送機

Cascade clocking is a concept to reduce the total pressure loss incurred in a multi-stage axial compressor by adjusting properly the circumferential position of the downstream stator vane relative to the upstream stator vane. The head investigator discovered the fact that the same concept can be applied to reduce fan tone noise in the case of a multi-stage fan such as used for the propulsion system of the next generation supersonic transport where the fan bypass ratio is low accordingly, the fan pressure ratio is high and a two or three stage fan is required.In order to apply the cascade clocking concept to tone noise reduction, the number of rotor blades should be the same for multiple stages and also the number of stator vanes should be the same. Then, the tone frequency is the same for multiple stages and the circumferential mode of the tone becomes identical. There is a possibility to cancel the pressure wave of the tone generated by the first stage by the pressure wave of the tone … More generated by the second stage based on the principle of superposition.The purpose of this project is to confirm experimentally the possibility to reduce tone noise by the concept of cascade clocking and also to find out numerically the condition necessary for the cascade clocking to be optimized.A two-stage axial compressor having 32 rotor blades for the first and the second stages and 38 stator vanes for both stages were used for the experiment. It has the ability of stator vane clocking in continuous fashion and that of rotor blade clocking at every 1/8 pitch.Results show that stator vane clocking can reduce the tone noise by as much as 18 dB. The level of noise reduction depends on rotational speed of the compressor for a fixed rotor blade setting for both stages. However, the combination of rotor blade clocking and stator vane clocking can give the maximum reduction mentioned above. Numerical calculation well explains the tone noise level variation against cascade clocking as obtained by experiments. Less

级联时钟是通过正确调整下游定子叶片相对于上游定子叶片的圆周位置来减少多阶段轴向压缩机中产生的总压力损失的概念。首席调查员发现了一个事实，即在多阶段风扇的情况下，可以应用相同的概念来降低风扇音调噪音，例如用于下一代超音速运输的推进系统，在该系统的推进系统中，风扇旁路比相应较低，风扇压力比为较高，并且需要两个或三个阶段的风扇，以便将级数的概念应用于级联时钟相同的位置。应该是一样的。然后，对于多个阶段的音调频率相同，音调的圆周模式变得相同。有可能通过音调的压力波消除第一阶段产生的音调的压力波……第二阶段产生的是基于叠加原则而产生的。该项目的目的是通过实验确认级联时钟概念的概念来确认音调噪声的可能性，并以数值为单位的速度量的速度来确认级别的条件，以实现两层型号的速度。两个阶段的定子叶片和38个定子均用于实验。它具有以连续的方式计时的定子叶片的能力，并且在每1/8螺距上时钟的转子刀片的能力表明，定子叶片时钟可以将音调噪声降低多达18 dB。降低水平的水平取决于两个阶段的固定转子叶片设置的压缩机的旋转速度。但是，转子叶片时钟和定子叶片时钟的组合可以给上述最大减少。数值计算很好地解释了通过实验获得的级联时钟的音调噪声水平变化。较少的