scholarly journals Measurement of the Local Sound Pressure on a Bias-Flow Liner Using High-Speed Holography and Tomographic Reconstruction

IEEE Access ◽  
2019 ◽  
Vol 7 ◽  
pp. 153466-153474 ◽  
Author(s):  
Andres E. Ramos Ruiz ◽  
Johannes Gurtler ◽  
Robert Kuschmierz ◽  
Jurgen W. Czarske
Keyword(s):  
High Speed ◽  
Sound Pressure ◽  
Tomographic Reconstruction ◽  
Bias Flow ◽  
Local Sound

scholarly journals Dense U-Net for Limited Angle Tomography of Sound Pressure Fields

2021 ◽  
Vol 11 (10) ◽  
pp. 4570
Author(s):  
Oliver Rothkamm ◽  
Johannes Gürtler ◽  
Jürgen Czarske ◽  
Robert Kuschmierz
Keyword(s):  
Measurement Errors ◽  
Sound Pressure ◽  
Tomographic Reconstruction ◽  
Synthetic Data ◽  
Projection Data ◽  
Quantitative Measurements ◽  
Pressure Fields ◽  
The Neural Network ◽  
Bias Flow ◽  
3D Information

Tomographic reconstruction allows for the recovery of 3D information from 2D projection data. This commonly requires a full angular scan of the specimen. Angular restrictions that exist, especially in technical processes, result in reconstruction artifacts and unknown systematic measurement errors. We investigate the use of neural networks for extrapolating the missing projection data from holographic sound pressure measurements. A bias flow liner was studied for active sound dampening in aviation. We employed a dense U-Net trained on synthetic data and compared reconstructions of simulated and measured data with and without extrapolation. In both cases, the neural network based approach decreases the mean and maximum measurement deviations by a factor of two. These findings can enable quantitative measurements in other applications suffering from limited angular access as well.

scholarly journals Berührungslose Messung des lokalen Schalldrucks mittels Hochgeschwindigkeits-Holographie / Non-invasive measurement of the local sound pressure using high-speed holography

2018 ◽  
Vol 85 (s1) ◽  
pp. s2-s6
Author(s):  
Andrés Eduardo Ramos Ruiz ◽  
Johannes Gürtler ◽  
Robert Kuschmierz ◽  
Jürgen Czarske
Keyword(s):  
High Speed ◽  
Sound Pressure ◽  
Non Invasive ◽  
Local Sound ◽  
Invasive Measurement

Zusammenfassung Für die Lärmreduzierung von Flugzeugtriebwerken kommen perforierte Bleche mit dahinterliegender Kavität (sogenannte Liner) zum Einsatz. Das aeroakustische Dämpfungsprinzip dieser Elemente beruht auf der Wechselwirkung von Schall und Strömung. Bisherige physikalische Modelle der Dämpfungsprozesse erlauben jedoch nicht die notwendige Entwicklung effizienterer Liner, da die aeroakustische Wechselwirkung noch nicht vollständig verstanden ist. Daher ist die Kenntnis relevanter Größen, wie die lokale Schalldruckverteilung, entscheidend für das Verständnis der lokalen Dämpfungsprozesse. Dazu präsentieren wir ein kamerabasiertes Messsystem für die zweidimensionale nicht-invasive ortsaufgelöste Schalldruckbestimmung.

Effect of Pantograph and Bogie on Interior Noise of High-Speed Train in Tunnel

2013 ◽  
Vol 664 ◽  
pp. 191-196
Author(s):  
You Gang Xiao ◽  
Yu Shi
Keyword(s):  
High Speed ◽  
Sound Pressure ◽  
Broad Band ◽  
Pressure Level ◽  
Channel Noise ◽  
High Speed Train ◽  
Noise Sources ◽  
Vehicle Noise ◽  
Measurement And Analysis ◽  
Analysis System

For clarifying the noise in tunnel affected by pantograph and bogie, which are the most important noise sources, the noises near pantograph and bogie in a high-speed train were tested by multi-channel noise measurement and analysis system in tunnel, and compared with those measured outside the High-speed train and on an open field. The results show that the interior vehicle noise is spatially non-homogeneous in the whole carriage, the larger sound pressure level (SPL) near pantograph are next to ceiling, and near bogie next to floor. The noise spectra show a broad band feature, and dominated by the frequency contents among 100Hz-2kHz, so the countermeasures against noise should be within these range.

High-speed Tomographic Reconstruction Employing Fourier Methods

1997 ◽  
Vol 3 (4) ◽  
pp. 255-274 ◽  
Author(s):  
Stefan Brantner ◽  
Rupert C.D. Young ◽  
David Budgett ◽  
Chris R. Chatwin
Keyword(s):  
High Speed ◽  
Tomographic Reconstruction ◽  
Fourier Methods

Grid Requirements for Multiscale Resolution in Separated Unsteady High Speed Turbulent Flows

2006 ◽  
Author(s):  
D. Basu ◽  
A. Hamed ◽  
K. Das
Keyword(s):  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Turbulent Flows ◽  
Sound Pressure Level ◽  
High Speed ◽  
Sound Pressure ◽  
Pressure Fluctuations ◽  
Pressure Level ◽  
Navier Stokes ◽  
Detached Eddy Simulation

This study deals with the computational grid requirements in multiscale simulations of separated turbulent flows at high Reynolds number. The two-equation k-ε based DES (Detached Eddy Simulation) model is implemented in a full 3-D Navier-Stokes solver and numerical results are presented for transonic flow solution over an open cavity. Results for the vorticity, pressure fluctuations, SPL (Sound Pressure level) spectra and for modeled and resolved TKE (Turbulent Kinetic Energy) are presented and compared with available experimental data and with LES results. The results indicate that grid resolution significantly influences the resolved scales and the peak amplitude of the unsteady sound pressure level (SPL) and turbulent kinetic energy spectra.

4103 Investigation of vibration response of spacecraft due to local sound pressure level increase

2007 ◽  
Vol 2007.5 (0) ◽  
pp. 351-352
Author(s):  
Masahiro TSUCHIHASHI ◽  
Qinzhong SHI ◽  
Shigemasa ANDO ◽  
Mikio SAITOH
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Pressure Level ◽  
Vibration Response ◽  
Level Increase ◽  
Local Sound

A hybrid tomographic reconstruction algorithm for high speed X-ray tomography

2015 ◽  
Vol 196 ◽  
pp. 27-35 ◽  
Author(s):  
Xiaogang Yang ◽  
J. Ruud van Ommen ◽  
Jasper Schoormans ◽  
Robert F. Mudde
Keyword(s):  
High Speed ◽  
Tomographic Reconstruction ◽  
Reconstruction Algorithm ◽  
X Ray

A study of brake disc modal behaviour during squeal generation using high-speed electronic speckle pattern interferometry and near-field sound pressure measurements

2000 ◽  
Vol 214 (3) ◽  
pp. 285-296 ◽  
Author(s):  
M Reeves ◽  
N Taylor ◽  
C Edwards ◽  
D Williams ◽  
C. H. Buckberry
Keyword(s):  
High Speed ◽  
Sound Pressure ◽  
Surface Deformation ◽  
Speckle Pattern ◽  
Near Field ◽  
Electronic Speckle Pattern Interferometry ◽  
Brake Disc ◽  
Pressure Measurements ◽  
Near Field Sound ◽  
Field Sound

The out-of-plane surface vibration of a brake disc during naturally excited squeal has been investigated using a combination of high-speed electronic speckle pattern interferometry (ESPI) and near-field sound pressure measurements. Both techniques provide visualization and quantification of the time-resolved surface velocity. A mathematical description of disc brake squeal modal behaviour is proposed that predicts accurately all of the experimentally observed interferometry and sound field measurements. The complex mode description proposed here is in agreement with that proposed by others for drum brake squeal. This assumes that two identical diametral modes are excited simultaneously, identical except for a spatial and temporal phase shift. The use of a near-field microphone array provided a convenient multipoint, non-contacting vibration probe which may find use in the study of other vibrations characterized by high surface amplitudes and efficient sound radiation. The high-speed ESPI provided a real-time visualization of surface deformation analogous to double- pulsed holographic interferometry, with the benefit of giving a true time series of the surface deformation during a single vibration cycle.

scholarly journals Numerical Modeling and Investigation on Aerodynamic Noise Characteristics of Pantographs in High-Speed Trains

Complexity ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Xiaoqi Sun ◽  
Han Xiao
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Sound Pressure ◽  
Noise Source ◽  
Flow Fields ◽  
Aerodynamic Noise ◽  
Far Field ◽  
Frequency Bands ◽  
Noise Characteristics ◽  
High Speed Trains

Pantographs are important devices on high-speed trains. When a train runs at a high speed, concave and convex parts of the train cause serious airflow disturbances and result in flow separation, eddy shedding, and breakdown. A strong fluctuation pressure field will be caused and transformed into aerodynamic noises. When high-speed trains reach 300 km/h, aerodynamic noises become the main noise source. Aerodynamic noises of pantographs occupy a large proportion in far-field aerodynamic noises of the whole train. Therefore, the problem of aerodynamic noises for pantographs is outstanding among many aerodynamics problems. This paper applies Detached Eddy Simulation (DES) to conducting numerical simulations of flow fields around pantographs of high-speed trains which run in the open air. Time-domain characteristics, frequency-domain characteristics, and unsteady flow fields of aerodynamic noises for pantographs are obtained. The acoustic boundary element method is used to study noise radiation characteristics of pantographs. Results indicate that eddies with different rotation directions and different scales are in regions such as pantograph heads, hinge joints, bottom frames, and insulators, while larger eddies are on pantograph heads and bottom frames. These eddies affect fluctuation pressures of pantographs to form aerodynamic noise sources. Slide plates, pantograph heads, balance rods, insulators, bottom frames, and push rods are the main aerodynamic noise source of pantographs. Radiated energies of pantographs are mainly in mid-frequency and high-frequency bands. In high-frequency bands, the far-field aerodynamic noise of pantographs is mainly contributed by the pantograph head. Single-frequency noises are in the far-field aerodynamic noise of pantographs, where main frequencies are 293 Hz, 586 Hz, 880 Hz, and 1173 Hz. The farther the observed point is from the noise source, the faster the sound pressure attenuation will be. When the distance of two adjacent observed points is increased by double, the attenuation amplitude of sound pressure levels for pantographs is around 6.6 dB.

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