Active control of multimodal tonal noise propagated in circular duct with axial subsonic mean flow until M=0.3

2008 ◽  
Vol 123 (5) ◽  
pp. 3574-3574
Author(s):  
Martin Glesser ◽  
Emmanuel Friot ◽  
Muriel Winninger ◽  
Cédric Pinhède ◽  
Alain Roure
Keyword(s):  
Active Control ◽  
Mean Flow ◽  
Tonal Noise ◽  
Circular Duct

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.

Active Control of a Circular Membrane to Reduce Transient Noise Transmission

1995 ◽  
Vol 117 (3A) ◽  
pp. 252-258 ◽  
Author(s):  
J. L. van Niekerk ◽  
B. H. Tongue
Keyword(s):  
Feedback Control ◽  
Active Control ◽  
Sliding Mode ◽  
Control Strategies ◽  
Circular Membrane ◽  
Velocity Feedback ◽  
Circular Duct ◽  
Control Approach ◽  
Noise Transmission

An active control approach that reduces transient noise transmission through a membrane in a circular duct is presented. Discrete sections of piezo-electrical film, PVDF, are used as actuators to adjust the tension of the membrane. Different control strategies, such as optimal, sliding mode and velocity feedback control, are investigated analytically and then implemented experimentally. It is shown that velocity feedback control is the more effective, stable controller for this application.

scholarly journals Active control of periodic fan noise in laptops: spectral width requirements in a delayed buffer implementation

2009 ◽  
Vol 7 (02) ◽  
Author(s):  
H. A. Cordourier-Maruri ◽  
F. Orduña-Bustamante
Keyword(s):  
Active Control ◽  
High Performance ◽  
Active Noise Control ◽  
Spectral Width ◽  
Tonal Noise ◽  
Successful Operation ◽  
Noise Sources ◽  
Fan Noise ◽  
Audio Processing ◽  
Cooling Fans

An active control system intended for the reduction of strictly periodic noise components in computer cooling fans is described, which is based on high‐performance digital sound device architectures found in some personal computers. The system overcomes causality and synchronization constrains imposed by delayed buffering, as usually found in computer audio processing. Performance of the system is demonstrated and evaluated through measurements in a physical implementation of active noise control of synthetic tones combined with laptop fan noise, carried out under anechoic and slightly everberant conditions. Tests on other types of tonal noise sources, like an electrical transformer, were also carried out. However, its wider applicability to the cancellation of tonal noise has been proved compromised by weak periodicity issues found and reported in this work. Also, a study of noise spectral width requirements for successful operation is presented.

A compact active control system for tonal noise reduction in axial fans

Noise Notes ◽  
2007 ◽  
Vol 6 (3) ◽  
pp. 37-46
Author(s):  
Anthony Gerard ◽  
Alain Berry ◽  
Patrice Masson
Keyword(s):  
Control System ◽  
Noise Reduction ◽  
Active Control ◽  
Tonal Noise ◽  
Axial Fans ◽  
Active Control System

Acoustic Analysis of a Rotary Control Valve

2014 ◽  
Author(s):  
Filippo Carlo Bossi ◽  
Stefano Malavasi
Keyword(s):  
High Performance ◽  
Acoustic Analysis ◽  
Fluid Dynamic ◽  
Plate Thickness ◽  
Broad Band ◽  
Control Valve ◽  
Experimental Tests ◽  
Rotary Valve ◽  
Tonal Noise ◽  
Circular Duct

High performance control valves may be subjected to noise problems especially when gas is the operating fluid. Depending on some geometric characteristics, the noise production can be characterized by broad band noise or tonal noise. When the latter condition occurs, the generated noise could overcome the limit of acceptance and the device does not respect the standard of usability. In a previous work, a dependency between the tonal noise and the main geometrical characteristics of a control rotary valve has been settled by experimental tests. Starting from these fluid dynamic observations in this work we coupled the modal analysis of the structure with experimental data to deeply understand this phenomenon. The natural frequencies of different perforated plates placed in a circular duct (configuration which mimics the full open control valve condition) are therefore considered to verify which of them are responsible of the tonal noise, generated by the interaction between the flow field and the acoustic one, observed in the experimental tests. To do this, the frequency modes consistent with the tonal noise generation, are numerically investigated by changing the geometrical characteristic of the device. By considering the rotary valve fully open, we especially investigated the effects of the plate thickness, the hole diameter and distribution.

Active control behavior on the flow pattern in a circular duct

2021 ◽  
Author(s):  
Sher Afghan Khan ◽  
Ridwan ◽  
Imran Mokashi ◽  
Arvind Kumar ◽  
Suheel J.I ◽  
...  
Keyword(s):  
Flow Pattern ◽  
Active Control ◽  
Circular Duct ◽  
Control Behavior
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