Experimental and computational investigation of the effect of blade sweep on acoustic characteristics of axial fan

Microphone arrays can be used to detect sound sources on rotating machinery. For this study, experiments with three different axial fans, featuring backward-skewed, unskewed, and forward-skewed blades, were conducted in a standardized fan test chamber. The measured data are processed using the virtual rotating array method. Subsequent application of beamforming and deconvolution in the frequency domain allows the localization and quantification of separate sources, as appear at different regions on the blades. Evaluating broadband spectra of the leading and trailing edges of the blades, phenomena governing the acoustic characteristics of the fans at different operating points are identified. This enables a detailed discussion of the influence of the blade design on the radiated noise.

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Computational investigation of aerodynamic and acoustic characteristics of an ultrahigh-bypass ratio counter-rotating fan

VESTNIK of the Samara State Aerospace University ◽

10.18287/2541-7533-2018-17-2-68-79 ◽

2018 ◽

Vol 17 (2) ◽

pp. 68

Author(s):

Ya. M. Druzhinin ◽

V. I. Mileshin ◽

A. A. Rossikhin

Keyword(s):

Computational Investigation ◽

Acoustic Characteristics ◽

Bypass Ratio

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Computational Investigation Of Aerodynamic And Acoustic Characteristics Of Counter-Rotating Fan With Ultra High Bypass Ratio

10.29008/etc2017-146 ◽

2017 ◽

Author(s):

Iaroslav Druzhinin ◽

Anton Rossikhin ◽

Victor Mileshin

Keyword(s):

Computational Investigation ◽

Acoustic Characteristics ◽

Bypass Ratio

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Numerical and Experimental Investigation of Acoustic Characteristics of Model Ultra High Bypass Ratio Counter Rotating Fan

Volume 2B: Turbomachinery ◽

10.1115/gt2018-76878 ◽

2018 ◽

Author(s):

Anton Rossikhin ◽

Iaroslav Druzhinin ◽

Iurii Khaletskii ◽

Victor Mileshin

Keyword(s):

Strong Influence ◽

Aircraft Engine ◽

Quantitative Agreement ◽

Computational Investigation ◽

Test Rig ◽

Acoustic Characteristics ◽

Operational Conditions ◽

3 Dimensional ◽

Numerical Investigations ◽

Bypass Ratio

A computational investigation of acoustic characteristics of model ducted counter-rotating fan COBRA-1 with ultra-high bypass ratio BPR = 20, developed in CIAM in the framework of European Project COBRA (Innovative Counter rOtating fan system for high Bypass Ratio Aircraft engine), is presented in the paper. Calculations of acoustic characteristics of the fan were performed at five operational conditions. For three of them the sums of rotation frequencies of rotors corresponded to those expected for approach conditions, and they differed from each other by relations between frequencies of rotors, and for other two the sums of rotation frequencies corresponded to cutback and sideline operational conditions. Numerical investigations were conducted using the method of 3D numerical calculation of interaction between fan rows implemented in 3DAS (3 Dimensional Acoustics Solver) CIAM in-house solver. The data were compared with the results of the experiments conducted in the CIAM test rig C-3A. The results of comparison show satisfactory qualitative and, in some positions of microphones, quantitative agreement between the results of the simulation and the experiment. Both results demonstrate strong influence of relation between rotation frequencies of rotors on acoustic characteristics and significant dominance of noise radiated from the nozzle over the noise radiated from the inlet.

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Prosodic Impairment Associated With Traumatic Brain Injury

Perspectives on Neurophysiology and Neurogenic Speech and Language Disorders ◽

10.1044/nnsld19.3.97 ◽

2009 ◽

Vol 19 (3) ◽

pp. 97-102

Author(s):

Billy Irwin

Keyword(s):

Traumatic Brain Injury ◽

Brain Injury ◽

Detailed Analysis ◽

Acoustic Characteristics ◽

Individual Variations

Abstract Purpose: This article discusses impaired prosody production subsequent to traumatic brain injury (TBI). Prosody may affect naturalness and intelligibility of speech significantly, often for the long term, and TBI may result in a variety of impairments. Method: Intonation, rate, and stress production are discussed in terms of the perceptual, physiological, and acoustic characteristics associated with TBI. Results and Conclusions: All aspects of prosodic production are susceptible to the effects of damage resulting from TBI. There are commonly associated prosodic impairments; however, individual variations in specific aspects of prosody require detailed analysis.

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