Engine noise source breakdowns from an improved inverse method (AFINDS) of processing phased array measurements

2014 ◽  
Author(s):  
Brian J. Tester
Keyword(s):  
Inverse Method ◽  
Phased Array ◽  
Noise Source ◽  
Engine Noise ◽  
Array Measurements

Pletharrays for aeroacoustic phased array applications

2017 ◽  
Vol 16 (4-5) ◽  
pp. 202-229 ◽  
Author(s):  
James R Underbrink
Keyword(s):  
Wind Tunnel ◽  
Phased Array ◽  
Noise Source ◽  
Array Element ◽  
Source Imaging ◽  
Array Measurements ◽  
Extensive Measurement ◽  
Transonic Wind Tunnel

“Pletharrays” are introduced, motivated, and presented for application to aeroacoustic phased array measurements. Pletharrays contain a plethora of arrays composed from a modest to high number of array elements to field a remarkably large number of high element count arrays for use in noise source imaging applications. Pletharrays that have been deployed for closed jet transonic wind tunnel, static engine ground, open jet wind tunnel, and flyover phased array tests are presented. Tremendous array element leverage to provide extensive measurement flexibility and fidelity are demonstrated.

Acoustic Double Holography Method and its Application to Engine Noise Research

1997 ◽  
Author(s):  
Milsuo Nakano ◽  
Masao Nagamatsu ◽  
Kohei Suzuki ◽  
Takuya Yoshimura
Keyword(s):  
Noise Source ◽  
Near Field ◽  
Wave Length ◽  
Pressure Data ◽  
Acoustic Holography ◽  
Engine Noise ◽  
Simplified Approach ◽  
Noise Shielding ◽  
Full Load Operation ◽  
Control Work

Abstract The acoustic holography (AH) method with single measuring plane has been well known as the conventional method and can be implemented by far field measurement with simple instruments. However, the noise source resolution of the AH is not sufficient. In order to improve the resolution in the noise source identification, several kinds of the acoustic holography methods have been so far proposed. For example, the near field acoustic holography (NAH) can provide high and accurate resolution of the holography by the nearfield measurement. However, the nearfield measurement within one wave length is sometimes impossible in the actual circumstances. The Acoustic Double Holography (A D H) proposed in this paper is a simplified approach with higher resolution of the noise source locations than that of the conventional AH methods. The ADH method basically uses dual measuring planes and does not require nearfield measurement. The sound pressure data detected on the rear plane are transformed into the virtual pressure data on the front plane taking into account of the distance between the plane and the object. Comparing the virtual pressure data with the actual data measured on the front plane, resolution on holography can be improved significantly. Computer simulation and an experiment with two loud speakers were executed in order to confirm the fundamental feature of the proposed method. Several advantages on the method with respect to resolution over the conventional AH method were discussed. Furthermore, the ADH measurement was carried out on running engine under the full load operation. Through these results, the highly noise radiating areas on the engine surface were detected and reduced with noise shielding material. The overall engine noise level was reduced by 1.5dBA as the first stage in this noise control work.

scholarly journals Source Contribution Analysis for Exterior Noise of a High-Speed Train: Experiments and Simulations

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Jie Zhang ◽  
Xinbiao Xiao ◽  
Dewei Wang ◽  
Yan Yang ◽  
Jing Fan
Keyword(s):  
High Speed ◽  
Noise Source ◽  
High Speed Train ◽  
Noise Sources ◽  
Sound Sources ◽  
Lower Region ◽  
Source Contribution ◽  
Array Measurements ◽  
Noise Characteristics ◽  
Train Speed

This paper presents a detailed investigation into the contributions of different sound sources to the exterior noise of a high-speed train both experimentally and by simulations. The in situ exterior noise measurements of the high-speed train, including pass-by noise and noise source identification, are carried out on a viaduct. Pass-by noise characteristics, noise source localizations, noise source contributions of different regions, and noise source vertical distributions are considered in the data analysis, and it is shown how they are affected by the train speed. An exterior noise simulation model of the high-speed train is established based on the method of ray acoustics, and the inputs come from the array measurements. The predicted results are generally in good agreement with the measurements. The results show that for the high-speed train investigated in this paper, the sources with the highest levels are located at bogie and pantograph regions. The contributions of the noise sources in the carbody region on the pass-by noise increase with an increasing distance, while those in the bogie and train head decrease. The source contribution rates of the bogie and the lower region decrease with increasing train speed, while those of the coach centre increase. At a distance of 25 m, the effect of the different sound sources control on the pass-by noise is analysed, namely, the lower region, bogie, coach centre, roof region, and pantograph. This study can provide a basis for exterior noise control of high-speed trains.

scholarly journals Limitations of Phased Array Beamforming in Open Rotor Noise Source Imaging

AIAA Journal ◽  
2014 ◽  
Vol 52 (8) ◽  
pp. 1810-1817 ◽  
Author(s):  
Csaba Horváth ◽  
Edmane Envia ◽  
Gary G. Podboy
Keyword(s):  
Phased Array ◽  
Noise Source ◽  
Source Imaging ◽  
Rotor Noise ◽  
Open Rotor ◽  
Array Beamforming

scholarly journals Jet-Surface Interaction Test: Phased Array Noise Source Localization Results

2012 ◽  
Author(s):  
Gary G. Podboy
Keyword(s):  
Source Localization ◽  
Phased Array ◽  
Noise Source ◽  
Jet Noise ◽  
Companion Paper ◽  
Far Field ◽  
Sound Waves ◽  
Axial Distribution ◽  
Noise Sources ◽  
Interaction Test

An experiment was conducted to investigate the effect that a planar surface located near a jet flow has on the noise radiated to the far-field. Two different configurations were tested: 1) a shielding configuration in which the surface was located between the jet and the far-field microphones, and 2) a reflecting configuration in which the surface was mounted on the opposite side of the jet, and thus the jet noise was free to reflect off the surface toward the microphones. Both conventional far-field microphone and phased array noise source localization measurements were obtained. This paper discusses phased array results, while a companion paper discusses far-field results. The phased array data show that the axial distribution of noise sources in a jet can vary greatly depending on the jet operating condition and suggests that it would first be necessary to know or be able to predict this distribution in order to be able to predict the amount of noise reduction to expect from a given shielding configuration. The data obtained on both subsonic and supersonic jets show that the noise sources associated with a given frequency of noise tend to move downstream, and therefore, would become more difficult to shield, as jet Mach number increases. The noise source localization data obtained on cold, shock-containing jets suggests that the constructive interference of sound waves that produces noise at a given frequency within a broadband shock noise hump comes primarily from a small number of shocks, rather than from all the shocks at the same time. The reflecting configuration data illustrates that the law of reflection must be satisfied in order for jet noise to reflect off of a surface to an observer, and depending on the relative locations of the jet, the surface, and the observer, only some of the jet noise sources may satisfy this requirement.

scholarly journals Phased Array Measurements from Landing Gear Models

2007 ◽  
Author(s):  
Alexander Quayle ◽  
Ann Dowling ◽  
Holger Babinsky ◽  
William Graham ◽  
Yu Liu
Keyword(s):  
Phased Array ◽  
Landing Gear ◽  
Array Measurements
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