Axial Flow Compressor Noise Studies

Tyler, John M.; Sofrin, T. G.

doi:10.4271/620532

Cited by 559 publications

(412 citation statements)

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“…This is consistent with the present result. For axial flow compressors, Tyler and Sofrin [7] have shown that the pressure fluctuation decays axially when the pressure pattern at the compressor face rotates around the rotor at subsonic speed. This is caused by the cancelling of the pressure waves from different circumferential location and is called "duct cut-off" and used to reduce noise from axial flow fans.…”

Section: Pressure Fluctuation At the Stator Inlet And The Volute Outletmentioning

confidence: 99%

Phase Resonance in a Centrifugal Compressor

Nishiyama¹,

Suzuki²,

Yonezawa³

et al. 2011

International Journal of Fluid Machinery and Systems

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Section: Pressure Fluctuation At the Stator Inlet And The Volute Outletmentioning

confidence: 99%

Phase Resonance in a Centrifugal Compressor

Nishiyama¹,

Suzuki²,

Yonezawa³

et al. 2011

International Journal of Fluid Machinery and Systems

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“…Equation (89) is the Tyler-Sofrin (1962) condition. The remaining terms in the pressure fields give the following equation for the modal amplitudes:…”

Section: Radiation Produced By the Cascade Interactionmentioning

confidence: 99%

Upstream-radiated rotor–stator interaction noise in mean swirling flow

Cooper

Peake

2005

J. Fluid Mech.

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A major component of the noise in modern aeroengines is rotor-stator interaction noise generated when the wake from the rotating fan impinges on a stator row downstream. An analytically based model for the prediction of upstream-radiated rotor-stator interaction noise is described, and includes the important effect of mean swirling flow on both the rotor wake evolution and the acoustic response. The analytic nature of the model allows for the inclusion of all wake harmonics and enables the response at all blade passing frequencies to be determined.An asymptotic analysis based on large rotor blade number is used to model the evolution of the rotor wake downstream in a cylindrical duct carrying mean swirling flow. The equations governing the axial evolution of the wake simplify to three coupled first-order differential equations in the interior, while close to the duct walls, a boundary-layer correction is required in order to satisfy the impermeability conditions at the boundaries. At the stator location, the wake is used as input into a local linear cascade model at each radius. The interaction of each wake harmonic gives rise to acoustic waves of multiple azimuthal order which contribute to the pressure field radiated back upstream. This enables the total acoustic response to be determined in terms of cylindrical duct modes in mean swirling flow.The effect of stator blade geometry (thickness, camber, angle of attack) and rotorstator separation on the total upstream-radiated noise is determined. Blade geometry is shown to have a significant effect on the noise generated, and increasing the rotorstator gap can lead to large reductions in noise levels. Asymptotic treatment of the acoustic field, based on large azimuthal order, is also considered and used to identify the dominant contributions to the total pressure field resulting from the rotor-stator interaction. The ray structure of the acoustic modes in swirl is shown to be very different in some cases from that in uniform flow.

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“…The above-described boundary condition was applied to the duct without flow (Zorumski, 1973) and with uniform flow occurring both inside the duct and in the surrounding medium (Tyler, Sofrin, 1962). The next model, assuming diffraction of the sound waves at the duct outlet, although considerably complicated and demanding application of the Wiener-Hopf method (Noble, 1958), has been frequently applied both to the single mode (Snakowska, Wyrzykowski, 1986;Weinstein, 1969) and the multimode radiation (Joseph, Morfey, 1999; Snakowska, 1993; Snakowska et al, 1996; Snakowska, Idczak, 1997a, b; Snakowska, Jurkiewicz, 2010).…”

Section: Introductionmentioning

confidence: 99%

Experimental Verification of the Theoretical Model of Sound Radiation from an Unflanged Duct with Low Mean Flow

Gorazd

Jurkiewicz

Snakowska

2012

Archives of Acoustics

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The paper deals with experimental verification of results provided by theoretical approach to the problem of sound radiation from an unflanged duct with mean flow of the medium taking into account existence of all allowable wave modes and, in particular, occurrence of the so-called unstable wave, which results in decay of radiation on and in vicinity of the duct axis. The flow is assumed to be uniform with the source of flow located inside the duct, which is the case frequently occurring in industrial systems. Mathematical considerations, accounting for multimodal and multifrequency excitation and diffraction at the duct outlet, are based on the model of the semi-infinite unflanged hard duct with flow. In the experimental set-up a fan, mounted inside the duct served as the source of flow and noise at the same time modelled as an array of uncorrelated sources of broadband noise, what led to the axisymmetrical shape of the sound pressure directivity characteristics. The theoretical analysis was carried out for the root mean square acoustic pressure in the far-field conditions. Experimental results are presented in the form of the measured pressure directivity characteristics obtained for uniform flow directed inwards and outwards the duct compared to this observed for the zero-flow case. The directivity was measured in one-third octave bands throughout five octaves (500 Hz -16 kHz) which, for a duct with radius of 0.08 m, corresponds to the range 0.74-23.65 in the reduced frequency ka (Helmholtz number) domain. The results obtained are consistent with theoretical solutions presented by Munt and Savkar, according to whom the weakening of the on-axis and close-to-axis radiation should take place in the presence of medium flow. Experimental results of the present paper indicate that this effect is observed even for the Mach number as low as 0.036.

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Axial Flow Compressor Noise Studies

Cited by 559 publications

References 0 publications

Phase Resonance in a Centrifugal Compressor

Phase Resonance in a Centrifugal Compressor

Upstream-radiated rotor–stator interaction noise in mean swirling flow

Experimental Verification of the Theoretical Model of Sound Radiation from an Unflanged Duct with Low Mean Flow

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