A physical model for acoustic resonance in the annular cavity structure is developed to represent the typical characteristic when acoustic resonance occurs.Firstly,the measurement of sound pressure in the casing and r...A physical model for acoustic resonance in the annular cavity structure is developed to represent the typical characteristic when acoustic resonance occurs.Firstly,the measurement of sound pressure in the casing and rotor blades vibration is operated in a multistage high pressure compressor.The sharp peak frequency and discrete multi-tone occur in the frequency spectrum of sound pressure in the compressor,and the vibration of the first stage of rotor blades synchronously presents the high amplitude.The frequencies associated with rotor blades vibration can be calculated with rotating sound source theory.It is also confirmed that acoustic resonance occurs in the multistage compressor.With acoustic similarity principle,an annular cavity model is established to simulate the typical characteristics of acoustic resonance in the compressor based on Large Eddy Simulation(LES)and Lighthill acoustic analogy.The coupling relationship between cavity acoustic mode and disc vibration mode shape is expounded when acoustic resonance occurs in the model.And acoustic resonance will be locked in the certain flow rate range.All these characteristics match well with those occur in the multistage high pressure compressor.展开更多
由于蜗壳对离心泵流动诱导噪声的产生及传播具有重要影响,在原马蹄形断面蜗壳的基础上重新设计了一种矩形断面蜗壳,并将两种断面的蜗壳与同一叶轮组合进行流场数值模拟和声学求解.流动诱导噪声的求解基于Lighthill声类比理论,采用大涡...由于蜗壳对离心泵流动诱导噪声的产生及传播具有重要影响,在原马蹄形断面蜗壳的基础上重新设计了一种矩形断面蜗壳,并将两种断面的蜗壳与同一叶轮组合进行流场数值模拟和声学求解.流动诱导噪声的求解基于Lighthill声类比理论,采用大涡模拟和声学有限元法相结合的混合算法.在原型泵的基础上还分析了采用矩形隔舌和圆角隔舌的扬程、效率和声学性能差异,并对模拟结果进行了试验验证.计算结果表明:矩形断面蜗壳模型泵和马蹄形断面蜗壳模型泵的水力性能近似;2种断面模型泵内流动诱导噪声的主频均为叶片通过频率290 Hz;从内部流场的压力云图、速度矢量分布及方向分析可发现矩形断面蜗壳内的流动状态更佳;相对于马蹄形断面蜗壳,采用矩形断面蜗壳模型泵的声压级平均小5 d B,声学性能更优;相对于矩形隔舌模型,采用圆角隔舌模型泵的水力性能更优,声学性能也较好,声压级平均小4 d B.展开更多
低频水声通信是实现远距离水下无线通信的一种重要方式,在海洋科考、环境监测及军事等领域应用广泛。流噪声是制约低频水声通信传输距离的重要因素之一。不同于以往对充油的拖曳线列阵声呐的流噪声研究,由于低频水声通信系统常用换能器...低频水声通信是实现远距离水下无线通信的一种重要方式,在海洋科考、环境监测及军事等领域应用广泛。流噪声是制约低频水声通信传输距离的重要因素之一。不同于以往对充油的拖曳线列阵声呐的流噪声研究,由于低频水声通信系统常用换能器和裸露水听器实现水下信号的发送和接收,本文以该系统中裸露水听器流噪声为研究对象,采用大涡模拟方法( Large Eddy Simulation, LES )和声学类比方法对水听器周围的流场、声场进行数值模拟计算分析,研究在不同外形参数、运动参数下的水听器周围的流噪声。分析对比结果表明裸露水听器周围的流噪声对低频水声通信存在影响,且流噪声声压级随着运动速度的增加而提高。本研究为提升远程低频水声通信性能提供了噪声方面的理论基础。展开更多
基金co-supported by the Liaoning Natural Science Foundation Guiding Plan of China(No.2019-ZD0237)the National Science Foundation of China(Nos.51576009,1166114102051711530036)。
文摘A physical model for acoustic resonance in the annular cavity structure is developed to represent the typical characteristic when acoustic resonance occurs.Firstly,the measurement of sound pressure in the casing and rotor blades vibration is operated in a multistage high pressure compressor.The sharp peak frequency and discrete multi-tone occur in the frequency spectrum of sound pressure in the compressor,and the vibration of the first stage of rotor blades synchronously presents the high amplitude.The frequencies associated with rotor blades vibration can be calculated with rotating sound source theory.It is also confirmed that acoustic resonance occurs in the multistage compressor.With acoustic similarity principle,an annular cavity model is established to simulate the typical characteristics of acoustic resonance in the compressor based on Large Eddy Simulation(LES)and Lighthill acoustic analogy.The coupling relationship between cavity acoustic mode and disc vibration mode shape is expounded when acoustic resonance occurs in the model.And acoustic resonance will be locked in the certain flow rate range.All these characteristics match well with those occur in the multistage high pressure compressor.
文摘由于蜗壳对离心泵流动诱导噪声的产生及传播具有重要影响,在原马蹄形断面蜗壳的基础上重新设计了一种矩形断面蜗壳,并将两种断面的蜗壳与同一叶轮组合进行流场数值模拟和声学求解.流动诱导噪声的求解基于Lighthill声类比理论,采用大涡模拟和声学有限元法相结合的混合算法.在原型泵的基础上还分析了采用矩形隔舌和圆角隔舌的扬程、效率和声学性能差异,并对模拟结果进行了试验验证.计算结果表明:矩形断面蜗壳模型泵和马蹄形断面蜗壳模型泵的水力性能近似;2种断面模型泵内流动诱导噪声的主频均为叶片通过频率290 Hz;从内部流场的压力云图、速度矢量分布及方向分析可发现矩形断面蜗壳内的流动状态更佳;相对于马蹄形断面蜗壳,采用矩形断面蜗壳模型泵的声压级平均小5 d B,声学性能更优;相对于矩形隔舌模型,采用圆角隔舌模型泵的水力性能更优,声学性能也较好,声压级平均小4 d B.
基金Supported by the National Natural Science Foundation of China (Grant No.10772119)the Research Fund of State Key Laboratory of Ocean Engineering,Shanghai Jiao Tong University
文摘低频水声通信是实现远距离水下无线通信的一种重要方式,在海洋科考、环境监测及军事等领域应用广泛。流噪声是制约低频水声通信传输距离的重要因素之一。不同于以往对充油的拖曳线列阵声呐的流噪声研究,由于低频水声通信系统常用换能器和裸露水听器实现水下信号的发送和接收,本文以该系统中裸露水听器流噪声为研究对象,采用大涡模拟方法( Large Eddy Simulation, LES )和声学类比方法对水听器周围的流场、声场进行数值模拟计算分析,研究在不同外形参数、运动参数下的水听器周围的流噪声。分析对比结果表明裸露水听器周围的流噪声对低频水声通信存在影响,且流噪声声压级随着运动速度的增加而提高。本研究为提升远程低频水声通信性能提供了噪声方面的理论基础。
