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 Active Control of Contact Force for a Pantograph-Catenary System

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Jiqiang Wang
Keyword(s):  
Active Control ◽  
Contact Force ◽  
High Speed ◽  
Large Scale ◽  
Vibration Suppression ◽  
Numerical Study ◽  
Primary Objective ◽  
Geometric Framework ◽  
High Speed Trains ◽  
Catenary System

The performance of the high speed trains depends critically on the quality of the contact in the pantograph-catenary interaction. Maintaining a constant contact force needs taking special measures and one of the methods is to utilize active control to optimize the contact force. A number of active control methods have been proposed in the past decade. However, the primary objective of these methods has been to reduce the variation of the contact force in the pantograph-catenary system, ignoring the effects of locomotive vibrations on pantograph-catenary dynamics. Motivated by the problems in active control of vibration in large scale structures, the author has developed a geometric framework specifically targeting the remote vibration suppression problem based only on local control action. It is the intention of the paper to demonstrate its potential in the active control of the pantograph-catenary interaction, aiming to minimize the variation of the contact force while simultaneously suppressing the vibration disturbance from the train. A numerical study is provided through the application to a simplified pantograph-catenary model.

Numerical Study of Active Control of Interior Noise in a Structural-Acoustic Enclosure

2011 ◽  
Vol 486 ◽  
pp. 103-106
Author(s):  
Ming Gang Zhu ◽  
Guo Yong Jin ◽  
Na Feng
Keyword(s):  
Control System ◽  
Active Control ◽  
Lead Zirconate Titanate ◽  
Numerical Study ◽  
Sound Field ◽  
Lead Zirconate ◽  
Interior Noise ◽  
Placement Problem ◽  
Total Potential ◽  
Flexible Plates

This paper is concerned with the numerical study of active control of interior noise induced by the flexible plates in a coupled enclosure. A cabin-like enclosure with four acoustically rigid walls and two flexible plates is considered. Two types of actuators are used, i.e. acoustic actuators and distributed lead zirconate titanate piezoelectric (PZT) actuators instead of point force actuators. With the control system designed to globally reduce the sound field, different control configurations are considered, including the structural actuator on the incident panel, actuator on the receiving panel, acoustic actuator on the cavity, and their combinations. The effectiveness and performance of the control system corresponding to each configuration are studied numerically, and desirable placement problem of structural actuators in terms of total potential energy reduction are of particular interest.

Concrete in Engineered Barriers for Radioactive Waste Disposal Facilities: Phenomenological Study and Assessment of Long Term Performance

2013 ◽  
Author(s):  
Diederik Jacques ◽  
Norbert Maes ◽  
Janez Perko ◽  
Suresh C. Seetharam ◽  
Quoc Tri Phung ◽  
...  
Keyword(s):  
Phenomenological Study ◽  
Numerical Study ◽  
Effective Diffusivity ◽  
Nuclear Research ◽  
Radioactive Waste Disposal ◽  
Chemical Degradation ◽  
Scale Model ◽  
Research Centre ◽  
Pore Scale

The paper aims to highlight recent developments at the Belgian Nuclear Research Centre SCK•CEN in experimental and numerical study of the coupled physical-chemical behaviour of concrete subject to chemical degradation. The discussion mainly focusses on three interlinked research projects covering novel experimental methods to study the alteration of hydraulic and transport properties during carbonation and calcium leaching, a pore scale numerical model to capture microstructural changes due to the above degradation processes and a generic multiscale model aimed at determining evolution of the properties of a macrostructure over the long term. The paper also describes supplementary continuum scale numerical studies concerning concrete-clay interactions and geochemical impact on the physical structure of concrete. Preliminary findings from these studies show encouraging results such as the development of novel leaching, water permeability and diffusion apparatus, a robust pore scale model based on Lattice-Boltzmann method and a mesoscale study focused on the importance of interfacial transition zones on the effective diffusivity for linear and nonlinear diffusion problems.

Minimization of Maximum Acoustic Pressure Over Space and Frequency

2006 ◽  
Vol 220 (4) ◽  
pp. 447-455 ◽  
Author(s):  
W-K Tseng
Keyword(s):  
Active Control ◽  
Acoustic Pressure ◽  
Single Channel ◽  
Active Noise Control ◽  
Sound Field ◽  
Primary Field ◽  
Channel System ◽  
Secondary Sources ◽  
Active Noise ◽  
Channel Systems

This paper investigates the performance of a local active noise control system for broadband disturbance using the method of the maximum acoustic pressure minimization over space and frequency. Local active control only attenuates the disturbance at some specified positions, which is different from global active control where the disturbance is attenuated at all positions. The theory and simulations of the maximum acoustic pressure minimization over space and frequency using single-channel, two-channel, and three-channel systems are presented. The work presented in this paper is the first part of the study and only concerns a plane wave primary field with one, two, and three secondary sources for simplicity. Constrained minimization of the pressure is introduced, to achieve control over the pressure in both frequency and space. The results show that good attenuation is achieved at the microphone location or desired range over space and frequency using a single-channel system. However, better performance could be achieved using a two-channel or a three-channel system. In the next part of the study, a more realistic sound field like a diffuse field will be investigated.

Numerical study of sound field radiated from a circular duct with an open end

1998 ◽  
Vol 103 (5) ◽  
pp. 2839-2839
Author(s):  
Zhichi Zhu ◽  
Anqi Zhou ◽  
Dongtao Huang ◽  
Qing Guo
Keyword(s):  
Numerical Study ◽  
Sound Field ◽  
Circular Duct

Active control of compressor noise in the machinery room of refrigerators

2019 ◽  
Vol 67 (5) ◽  
pp. 350-362
Author(s):  
J. M. Ku ◽  
W. B. Jeong ◽  
C. Hong
Keyword(s):  
Control System ◽  
Active Control ◽  
Weighting Function ◽  
Reference Signal ◽  
Active Noise Control ◽  
Dominant Frequency ◽  
Time Signal ◽  
Frequency Noise ◽  
Sound Power ◽  
Fxlms Algorithm

The low-frequency noise generated by the vibration of the compressor in the machinery room of refrigerators is considered as annoying sound. Active noise control is used to reduce this noise without any change in the design of the compressor in the machinery room. In configuring the control system, various signals are measured and analyzed to select the reference signal that best represents the compressor noise. As the space inside the machinery room is small, the size of a speaker is limited, and the magnitude of the controller transfer function is designed to be small at low frequencies, the controller uses FIR filter structure converged by the FxLMS algorithm using the pre-measured time signal. To manage the convergence speed for each frequency, the frequency-weighting function is applied to FxLMS algorithm. A series of measurements are performed to design the controller and to evaluate the control performance. After the control, the sound power transmitted by the refrigerator is reduced by 9 dB at the first dominant frequency (408 Hz in this case) and 3 dB at the second dominant frequency (459 Hz here), and the overall sound power decreases by 2.6 dB. Through this study, an active control system for the noise generated by refrigerator compressors is established.

Active control of the scattered radiation with a reflecting surface

2019 ◽  
Vol 67 (3) ◽  
pp. 190-196
Author(s):  
Ning Han
Keyword(s):  
Control System ◽  
Active Control ◽  
Scattered Radiation ◽  
Sound Pressure ◽  
Sound Field ◽  
Control Area ◽  
Mirror Image ◽  
Three Dimension ◽  
Control Effect ◽  
Reflecting Surface

Based on a prediction method of the scattered sound pressure, an active control system was proposed in previous work for the three-dimension scattered radiation, where all the relevant simulations and experiments were implemented in three-dimensional free sound field. However, for practical applications, such as the anti-eavesdropping system or the stealth system for submarines, the sound field conditions are usually complex, and the most common case is the one with reflecting surface. It is questionable whether the previous control system is still effective in non-free sound field, or what improvements should be operated to ensure the control effect. In this article, based on the mirror image principle, two methods of calculating the control source strengths are proposed for the scattered radiation control, and numerical simulations with one-channel and multi-channel system are implemented to detect the corresponding control effect. It is seen that the local active control for the scattered radiation is still effective, and the reduction of the sound pressure level as well as the control area is extended with the increasement of the error sensors and control sources.

Numerical Study of the Mean and Filtered Characteristics of Turbulent Jets Impinging on Convex and Flat Surfaces Using LES

2012 ◽  
Author(s):  
Adra Benhacine ◽  
Zoubir Nemouchi ◽  
Lyes Khezzar ◽  
Nabil Kharoua
Keyword(s):  
Convex Surface ◽  
Numerical Study ◽  
Three Dimensional ◽  
Turbulent Jets ◽  
Scale Model ◽  
Wall Jet ◽  
Potential Core ◽  
Flat Surfaces ◽  
Free Jet ◽  
Eddy Simulation

A numerical study of a turbulent plane jet impinging on a convex surface and on a flat surface is presented, using the large eddy simulation approach and the Smagorinski-Lilly sub-grid-scale model. The effects of the wall curvature on the unsteady filtered, and the steady mean, parameters characterizing the dynamics of the wall jet are addressed in particular. In the free jet upstream of the impingement region, significant and fairly ordered velocity fluctuations, that are not turbulent in nature, are observed inside the potential core. Kelvin-Helmholtz instabilities in the shear layer between the jet and the surrounding air are detected in the form of wavy sheets of vorticity. Rolled up vortices are detached from these sheets in a more or less periodic manner, evolving into distorted three dimensional structures. Along the wall jet the Coanda effect causes a marked suction along the convex surface compared with the flat one. As a result, relatively important tangential velocities and a stretching of sporadic streamwise vortices are observed, leading to friction coefficient values on the curved wall higher than those on the flat wall.

Numerical study of active control by piezoelectric materials for fluid–structure interaction problems

2018 ◽  
Vol 435 ◽  
pp. 23-35 ◽  
Author(s):  
Shigeki Kaneko ◽  
Giwon Hong ◽  
Naoto Mitsume ◽  
Tomonori Yamada ◽  
Shinobu Yoshimura
Keyword(s):  
Active Control ◽  
Numerical Study ◽  
Piezoelectric Materials ◽  
Fluid Structure Interaction ◽  
Fluid Structure ◽  
Structure Interaction

Correlations between flow resistance and geometry in a model of the human nose

1993 ◽  
Vol 75 (4) ◽  
pp. 1767-1775 ◽  
Author(s):  
S. Schreck ◽  
K. J. Sullivan ◽  
C. M. Ho ◽  
H. K. Chang
Keyword(s):  
Nasal Congestion ◽  
Magnetic Resonance Images ◽  
Healthy Male Subject ◽  
Scale Model ◽  
Good Correspondence ◽  
Cross Sectional ◽  
Circular Duct ◽  
Pressure Losses ◽  
Dimensionless Analysis

The relationship between the pressure losses within the nasal airways and nasal geometry were studied in a 3:1 scale model. The geometry of the model was based on magnetic resonance images of the skull of a healthy male subject. Pressure measurements, flow visualization, and hot-wire anemometry studies were performed at flow rates that, in vivo, corresponded to flows of between 0.05 and 1.50 l/s. The influence of nasal congestion and the collapse of the external nares were examined by using modeling clay to simulate local constrictions in the cross section. A dimensionless analysis of the pressure losses within three sections of the airway revealed the influence of various anatomic dimensions on nasal resistance. The region of the exterior nose behaves as a contraction-expansion nozzle in which the pressure losses are a function of the smallest cross-sectional area. Losses in the interior nose resemble those associated with channel flow. The nasopharynx is modeled as a sharp bend in a circular duct. Good correspondence was found between the predicted and actual pressure losses in the model under conditions that stimulated local obstructions and congestion.

Sign in / Sign up

Export Citation Format

Share Document