Rotor wake characteristics relevant to rotor-stator interaction noise generation

Shaw, L. M.; Balombin, J. R.

doi:10.2514/6.1981-2031

Cited by 6 publications

(1 citation statement)

References 7 publications

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“…The velocity profile of the impeller discharge flow, especially the diffusion characteristics of the blade wake is measured by X hot-film anemometer, since the wake shows large amplitude in the profile of the absolute velocity and is considered to dominate the noise source of the BPF components. Shaw and Balombin (1981) for the absolute velocity of the axial blowers. The definitions of AV and AW are schematically shown in Fig.8.…”

Section: Model Of Surface Pressure Fluctuationmentioning

confidence: 99%

Evaluation and Prediction of Blade-Passing Frequency Noise Generated by a Centrifugal Blower

Ohta

Outa

Tajima

1994

Volume 1: Turbomachinery

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The blade-passing frequency noise, abbreviated to BPF noise, of low specific speed centrifugal blower is analyzed by separating the frequency-response of the transmission passage and the intensity of the noise source. Frequency-response has previously been evaluated by the authors using a one-dimensional linear wave model, and the results have agreed well with the experimental response in a practical range of the blower speed. In the present study, the intensity of the noise source is estimated by introducing the quasi-steady model of the blade wake impingement on the scroll surface. The effective location of the noise source is determined by analyzing the cross-correlation between measured data of the blower suction noise and pressure fluctuation on the scroll surface. Then, the surface density distribution of a dipole noise source is determined from pressure fluctuation expressed in terms of quasi-steady dynamic pressure of the traveling blade wake. Finally, the free-field noise level is predicted by integrating the density spectrum of the noise source over the effective source area. The sound pressure level of the blower suction noise is easily predicted by multiplying the free-field noise level by the frequency-response characteristics of the noise transmission passage.

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Section: Model Of Surface Pressure Fluctuationmentioning

confidence: 99%

Evaluation and Prediction of Blade-Passing Frequency Noise Generated by a Centrifugal Blower

Ohta

Outa

Tajima

1994

Volume 1: Turbomachinery

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The effect of duct on the inflow velocity at the propeller plane

Xie

Yuan-shuang

et al. 2020

2020 7th International Forum on Electrical Engineering and Automation (IFEEA)

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Strut or guide vane secondary flows and their effect on turbomachinery noise

Lakshminarayana

Thompson

Trunzo

1983

Journal of Aircraft

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Results of an investigation in which the turbomachinery rotor sound spectra were correlated with aerodynamic measurements of upstream strut secondary flow are reported. The aerodynamic measurements, carried out in an aeroacoustic turbomachinery facility, included mean-velocity and turbulence-intensity profiles across the wake and the secondary flow regions at the strut exit or rotor inlet. The measurements were carried out at incidence angles of 0, 4, 12, and -12 deg to the strut. The far-field acoustic measurements were carried out for all these operating conditions. The strut span was kept small to eliminate the wake interaction effects. The acoustic results correlated with the aerodynamic measurements indicate that secondary flow could be a significant noise source in cases where secondary flow/vortex strength is large.x,6,r Nomenclature = blade passing frequency = nondimensional radius = r/r i[p = sound pressure level = mean axial velocity at r/r tip = 0.75 = blade tip speed = local mean tangential and axial velocity, respectively = fluctuating turbulent velocity in the axial, tangential, and radial directions, respectively = axial, tangential, and radial directions, respectively = tangential probe distance nondimensionalized with respect to local rotor blade spacing = distance between hot wire and strut trailing edge for aerodynamic measurements and distance between rotor blade leading edge and strut trailing edge for acoustic measurements, nondimensionalized with respect to strut chord = flow incidence angle to the strut = tangential probe location, rad = axial velocity defect normalized by freestream velocity = strength of vortex = flow coefficient =U c /U t = tip = components in axial, tangential, and radial directions, respectively

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Rotor wake characteristics relevant to rotor-stator interaction noise generation

Cited by 6 publications

References 7 publications

Evaluation and Prediction of Blade-Passing Frequency Noise Generated by a Centrifugal Blower

Evaluation and Prediction of Blade-Passing Frequency Noise Generated by a Centrifugal Blower

The effect of duct on the inflow velocity at the propeller plane

Strut or guide vane secondary flows and their effect on turbomachinery noise

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