Comparison of sound field measurements and predictions in coupled volumes between numerical methods and scale model measurements

2013 ◽  
Vol 133 (5) ◽  
pp. 3530-3530
Author(s):  
Paul Luizard ◽  
Makoto Otani ◽  
Jonathan Botts ◽  
Lauri Savioja ◽  
Brian F. Katz
Keyword(s):  
Numerical Methods ◽  
Sound Field ◽  
Field Measurements ◽  
Scale Model

scholarly journals Spiral Sound Wave Transducer Based on the Longitudinal Vibration

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3674 ◽  
Author(s):  
Wei Lu ◽  
Yu Lan ◽  
Rongzhen Guo ◽  
Qicheng Zhang ◽  
Shichang Li ◽  
...  
Keyword(s):  
Sound Wave ◽  
Longitudinal Vibration ◽  
Three Dimensional ◽  
Low Frequency ◽  
Sound Field ◽  
Field Measurements ◽  
Sound Waves ◽  
Underwater Sound ◽  
Three Dimensional Finite Element ◽  
Wave Transducer

A spiral sound wave transducer comprised of longitudinal vibrating elements has been proposed. This transducer was made from eight uniform radial distributed longitudinal vibrating elements, which could effectively generate low frequency underwater acoustic spiral waves. We discuss the production theory of spiral sound waves, which could be synthesized by two orthogonal acoustic dipoles with a phase difference of 90 degrees. The excitation voltage distribution of the transducer for emitting a spiral sound wave and the measurement method for the transducer is given. Three-dimensional finite element modeling (FEM)of the transducer was established for simulating the vibration modes and the acoustic characteristics of the transducers. Further, we fabricated a spiral sound wave transducer based on our design and simulations. It was found that the resonance frequency of the transducer was 10.8 kHz and that the transmitting voltage resonance was 140.5 dB. The underwater sound field measurements demonstrate that our designed transducer based on the longitudinal elements could successfully generate spiral sound waves.

Active control of fan noise from high-bypass ratio aeroengines: a numerical study

2001 ◽  
Vol 105 (1053) ◽  
pp. 627-631
Author(s):  
P. Traub ◽  
F. Kennepohl ◽  
K. Heinig
Keyword(s):  
Active Control ◽  
Numerical Study ◽  
Active Noise Control ◽  
Sound Field ◽  
Primary Objective ◽  
Scale Model ◽  
Research Centre ◽  
Infinite Length ◽  
Circular Duct ◽  
Bypass Ratio

Abstract Under the national research project, dubbed Turbotech II, in which MTU Aero Engines, DLR Institute of Propulsion Technology and EADS Corporate Research Centre participate, active noise control (ANC) has been tested with a scale model fan of one metre diameter for a high bypass ratio aeroengine. MTU’s task in this project was to develop a computer code to predict the sound field in the intake duct of the fan-rig by the use of active control. The primary objective of the numerical study was to specify numbers of actuators (loudspeakers) and error sensors (microphones) and their positioning to control the harmonic sound power, radiated upstream to the duct intake. The computer model is based on the geometry of an annular or circular duct of rigid walls and infinite length, containing a subsonic axial uniform flow. The modal amplitudes of the primary sound field are input data. The actuators are modelled by acoustic monopoles. Two control algorithms have been used for achieving the control objective. The first consists simply in the reduction of the in-duct mean squared pressures. The second, so called modal control, is designed to cancel dominant modes selectively. Numerical results are presented using a typical configuration of wall mounted actuators and error sensors in the form of a number of rings uniformly distributed along the length of the intake duct. Guidelines have also been derived to design a favourable configuration of actuators and sensors. The findings of the numerical study are compared with the results of the ANC tests.

scholarly journals WAVE ACTION ON LARGE OFF-SHORE STRUCTURES

1976 ◽  
Vol 1 (15) ◽  
pp. 129 ◽  
Author(s):  
C.J. Apelt ◽  
A. Macknight
Keyword(s):  
Numerical Methods ◽  
Water Surface ◽  
Theoretical Method ◽  
Wave Force ◽  
Wave Action ◽  
Tidal Range ◽  
Scale Model ◽  
Wave Forces ◽  
Accurate Calculation ◽  
Scour Protection

The paper describes investigations carried out in order to design for the wave action, both wave force and scour, on large off-shore berthing structures sited approximately 1.3 miles (2.1 km) off-shore near Hay Point, North Queensland, in 56 feet (17 m) of water at low tide, the tidal range being 20 feet (6 m). The region is a cyclone area and the structures must be capable of withstanding attack from maximum predicted waves with period of 8.25 seconds and amplitude of 24 feet (7.3 m). The main units in the berthing structures are concrete caissons sunk on to the ocean bed and the largest of these have plan dimensions of approximately 150 feet (46.7 m) by 135 feet (41.4 m) with four columns approximately 40 feet (12.2 m) square projecting through the water surface. No theoretical method available at the time of the investigation was capable of accurate calculation of wave forces on these structures. A scale model was tested to obtain wave forces and the paper compares results from the model with those of numerical methods and discusses the application of the results to the design functions. Scour effects were also modelled and the results used as the basis for design of scour protection.

scholarly journals Nozzles, turbulence, and jet noise prediction

2018 ◽  
Vol 860 ◽  
pp. 1-4 ◽  
Author(s):  
Jonathan B. Freund
Keyword(s):  
Prediction Accuracy ◽  
Jet Noise ◽  
Sound Field ◽  
Field Measurements ◽  
Detailed Comparison ◽  
Large Eddy Simulations ◽  
Noise Prediction ◽  
Large Eddy ◽  
Modelling Procedure ◽  
Flow Turbulence

Jet noise prediction is notoriously challenging because only subtle features of the flow turbulence radiate sound. The article by Brès et al. (J. Fluid Mech., vol. 851, 2018, pp. 83–124) shows that a well-constructed modelling procedure for the nozzle turbulence can provide unprecedented sub-dB prediction accuracy with modest-scale large-eddy simulations, as confirmed by detailed comparison with turbulence and sound-field measurements. This both illuminates the essential mechanisms of the flow and facilitates prediction for engineering design.

Optical fiber coupler array for multi-point sound field measurements

1997 ◽  
Vol 4 (1) ◽  
pp. A65-A68 ◽  
Author(s):  
Kentaro Nakamura ◽  
Koichiro Fukaya
Keyword(s):  
Optical Fiber ◽  
Sound Field ◽  
Field Measurements ◽  
Optical Fiber Coupler ◽  
Fiber Coupler

Prediction of subjective properties of a sound field in a concert hall with tenth‐scale model

1999 ◽  
Vol 105 (2) ◽  
pp. 1197-1197
Author(s):  
Koji Ishida ◽  
Kiyoshi Sugino ◽  
Hideki Tachibana
Keyword(s):  
Sound Field ◽  
Scale Model ◽  
Concert Hall

Comparison of 48‐point 3‐D anechoic and diffuse sound field measurements of directivity index

2005 ◽  
Vol 118 (3) ◽  
pp. 1859-1859
Author(s):  
Ron Scicluna ◽  
Mead Killion ◽  
Andy Haapapuro ◽  
Stephen Julstrom
Keyword(s):  
Sound Field ◽  
Field Measurements
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