Modeling and Analysis of Aerodynamic Noise in Milling Cutters

2006 ◽  
Vol 129 (1) ◽  
pp. 5-11 ◽  
Author(s):  
Karthikeyan Sampath ◽  
Shiv G. Kapoor ◽  
Richard E. DeVor
Keyword(s):  
High Speed ◽  
Noise Exposure ◽  
Noise Spectrum ◽  
Rotational Frequency ◽  
Face Milling ◽  
Broadband Noise ◽  
Aerodynamic Noise ◽  
Noise Generation ◽  
Modeling And Analysis ◽  
Exposure Limit

Aerodynamic noise generated in high speed face milling cutters is usually much higher than the noise exposure limit set by OSHA. Experiments were conducted on two different face milling cutters to understand the aerodynamic noise generation in face milling cutters. It is observed that dipole sources of noise are most important in determining the noise generation in rotating face milling cutters. The aerodynamic noise spectrum consists of discrete tones at the rotational frequency and a broad range of higher frequencies, with the broadband spectrum contributing significantly to overall noise. A mathematical model based on the Ffowcs Williams-Hawkings Equation is used to predict (un-weighted) aerodynamic noise. The noise predicted compares well with the experimental observations. The cutter gullet shape was found to be an important factor in determining broadband noise.

Numerical Analysis of the Surface Aerodynamic Noise of the CRH3 High Speed Train

2014 ◽  
Vol 1044-1045 ◽  
pp. 643-649
Author(s):  
Ji Zhou Liu ◽  
Ren Xian Li ◽  
Peng Xiang Cui
Keyword(s):  
High Speed ◽  
Noise Source ◽  
Radiation Power ◽  
Spectral Characteristics ◽  
Radiation Energy ◽  
Simulation Method ◽  
Acoustic Power ◽  
Broadband Noise ◽  
Aerodynamic Noise ◽  
High Speed Train

For high speed trains running at 300km/h or more, the aerodynamic noise becomes the primary noise source. A good knowledge of the location, spectral characteristics and propagation behavior of the noise source and the corresponding methods to reduce the effect of the aerodynamic noise are of crucial necessity during the design process of the high speed train. Based on the Lighthill Analogy, the pressure fluctuation of air at the surface of the train is acquired by simulating the flow field of a CRH3 high speed train running at 200 km/h, 300 km/h, 400 km/h and 500km/h by means of large eddy simulation method. By Fourier transformation, the distribution and the spectral characteristics of the surface acoustic dipole sources are obtained. The analysis of the results shows that the aerodynamic noise of the high speed train is a broadband noise with a strong radiation power band from 50Hz to 1000Hz. The dipole acoustic power calculated by statistically averaged on train surface is found to be proportional to the sixth power of running speed of the high speed train. The first and second bogie, the inter-car gap, the air deflector of the power train and the train nose of the last wagon are the main noise sources that contain high radiation energy.

scholarly journals Research on Aerodynamic Noise Reduction for High-Speed Trains

2016 ◽  
Vol 2016 ◽  
pp. 1-21 ◽  
Author(s):  
Yadong Zhang ◽  
Jiye Zhang ◽  
Tian Li ◽  
Liang Zhang ◽  
Weihua Zhang
Keyword(s):  
Noise Reduction ◽  
High Speed ◽  
Low Noise ◽  
Broadband Noise ◽  
Full Scale ◽  
Noise Model ◽  
Aerodynamic Noise ◽  
High Speed Train ◽  
Detached Eddy Simulation ◽  
Noise Sources

A broadband noise source model based on Lighthill’s acoustic theory was used to perform numerical simulations of the aerodynamic noise sources for a high-speed train. The near-field unsteady flow around a high-speed train was analysed based on a delayed detached-eddy simulation (DDES) using the finite volume method with high-order difference schemes. The far-field aerodynamic noise from a high-speed train was predicted using a computational fluid dynamics (CFD)/Ffowcs Williams-Hawkings (FW-H) acoustic analogy. An analysis of noise reduction methods based on the main noise sources was performed. An aerodynamic noise model for a full-scale high-speed train, including three coaches with six bogies, two inter-coach spacings, two windscreen wipers, and two pantographs, was established. Several low-noise design improvements for the high-speed train were identified, based primarily on the main noise sources; these improvements included the choice of the knuckle-downstream or knuckle-upstream pantograph orientation as well as different pantograph fairing structures, pantograph fairing installation positions, pantograph lifting configurations, inter-coach spacings, and bogie skirt boards. Based on the analysis, we designed a low-noise structure for a full-scale high-speed train with an average sound pressure level (SPL) 3.2 dB(A) lower than that of the original train. Thus, the noise reduction design goal was achieved. In addition, the accuracy of the aerodynamic noise calculation method was demonstrated via experimental wind tunnel tests.

Numerical Analysis of Aeroacoustic Noise for High-Speed Face Milling Cutters in Three Dimensional Unsteady Flow Fields

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Chunhui Ji ◽  
Zhanqiang Liu
Keyword(s):  
High Speed ◽  
Reference Frames ◽  
Acoustic Noise ◽  
Environmental Concern ◽  
Three Dimensional ◽  
Vertical Plane ◽  
Flow Fields ◽  
Face Milling ◽  
Noise Generation ◽  
Aeroacoustic Noise

Aeroacoustic noise produced by high speed face milling cutters is a serious environmental concern. This paper develops a modeling approach to investigate the aeroacoustic noise generation and propagation by the idling face milling cutters. The approach consists of two parts: (1) an aerodynamic model for evaluating the flow fields based on the Navier–Stokes (N–S) equation and (2) an aeroacoustic model for predicting the acoustic noise by using the Ffowcs Williams and Hawkings (FW–H) equation. Both the steady mode with the multiple reference frames (MRF) model and the unsteady mode with the sliding mesh technique by introducing steady flow variables as its initial fields are simulated. The cutter gullet regions and the insert rake face regions are found to be the primary contributors in noise generation through spectral analysis of noise sources. The acoustic noise in face milling is significantly affected by the cutter diameter and the number of cutter teeth. The noise directivity is found in vertical plane, and the irregular tooth spacing can spread the maximum sound power at the rotating frequency to higher frequencies. In addition, experiments are conducted to measure the acoustic noise from two high speed milling cutters. It is found that the experimental results are generally in good agreement with the simulations.

The generation of sound in turbulent motion

2008 ◽  
Vol 112 (1133) ◽  
pp. 381-394 ◽  
Author(s):  
G. M. Lilley
Keyword(s):  
Noise Reduction ◽  
Turbulent Flows ◽  
High Speed ◽  
Experimental Studies ◽  
Supersonic Jet ◽  
Jet Noise ◽  
Aerodynamic Noise ◽  
Turbulent Shear ◽  
Noise Generation ◽  
Physical Mechanisms

Abstract The present paper reviews and discusses the physical mechanisms of noise generation and reduction in turbulent flows with their applications towards aircraft noise reduction at takeoff and on the approach. This work began in 1948 when Lilley undertook an experimental investigation into the source of jet noise as a necessary precursor to finding methods for the reduction of high speed jet engine noise on civil jet airliners. Westley and Lilley completed this experimental programme in 1951, which included the design of a range of devices for high speed jet noise reduction. It was about this time that similar studies on jet noise were being started elsewhere and in particular by Lassiter and Hubbard in USA. The major contribution to the subject of turbulence as a source of noise came from Sir James Lighthill’s remarkable theory in 1952. In spite of the difficulties attached to theoretical and experimental studies on noise from turbulence, it is shown that with the accumulated knowledge on aerodynamic noise over the past 50 years, together with an optimisation of aircraft operations including flight trajectories, we are today on the threshold of approaching the design of commercial aircraft with turbofan propulsion engines that will not be heard above the background noise of the airport at takeoff and landing beyond 1-2km, from the airport boundary fence. It is evident that in the application of this work, which centres on the physical mechanisms relating to the generation of noise from turbulence and turbulent shear flows, to jet noise, there is not one unique mechanism of jet noise generation for all jet Mach numbers. This author in this publication has concentrated on what appears to be the dominant mechanism of noise generation from turbulence, where the mean convection speeds of the turbulence are subsonic. The noise generated at transonic and supersonic jet speeds invariably involves extra mechanisms, which are only briefly referred to here.

Towards Computational Prediction of Wind Turbine Flow and Noise

2017 ◽  
Author(s):  
Cheng Zhang ◽  
Murilo Basso
Keyword(s):  
Wind Energy ◽  
Wind Turbine ◽  
Local Community ◽  
Broadband Noise ◽  
Aerodynamic Noise ◽  
Cfd Modeling ◽  
Computational Domain ◽  
Noise Generation ◽  
Upwind Schemes ◽  
The Impact

Wind energy is a clean, renewable, and fast-growing energy source for power generation. However, the noise issue, especially the aerodynamic noise, has become a critical obstacle in wind energy development. To determine the impact of the wind turbine noise and to guide the design and siting of wind turbines to minimize the disturbances on the local community, better understanding of the noise generation mechanisms as well as more accurate noise prediction techniques are necessary. Computational fluid dynamics (CFD) modeling of the National Renewable Energy Laboratory (NREL) Phase VI wind turbine at different wind speeds and tip pitch angles have been performed using ANSYS Fluent. The computational domain extends about 3 times of the wind turbine blade radius in the upstream direction, and 6 times the blade radius in the downstream and transverse directions. The shear-stress transport (SST) k-omega turbulence model is used. Second-order upwind schemes are used for the momentum and turbulence equations. The predicted pressure coefficients and power are in good agreement with the experimental data. The effects of wind speed and tip pitch angle on noise generation have also been investigated using the broadband noise source model. The Ffowcs-Williams Hawkings equation is also currently being used to obtain the far-field noise.

Modeling and Prediction of Cutting Noise in the Face-Milling Process

2007 ◽  
Vol 129 (3) ◽  
pp. 527-530 ◽  
Author(s):  
Karthikeyan Sampath ◽  
Shiv G. Kapoor ◽  
Richard E. DeVor
Keyword(s):  
High Speed ◽  
Cutting Speed ◽  
Milling Process ◽  
Face Milling ◽  
Aerodynamic Noise ◽  
Noise Prediction ◽  
Vibration Data ◽  
Total Noise ◽  
Workpiece Vibration ◽  
The Face

A cutting noise prediction model is developed to relate the cutter-workpiece vibrations to the sound pressure field around the cutter in the high-speed face-milling process. The cutter-workpiece vibration data are obtained from a dynamic mechanistic face-milling force simulation model. The total noise predicted, based on both cutting noise and aerodynamic noise prediction, compares well to the noise observed experimentally in the face-milling process. Using the model, the effects of various machining and cutter geometry parameters are studied. It is shown that cutter geometry, machine dynamics, and cutting speed all play important roles in determining overall noise in face milling.

scholarly journals Numerical analysis of aerodynamic noise from pantograph in high-speed trains using lattice Boltzmann method

2019 ◽  
Vol 11 (7) ◽  
pp. 168781401986399 ◽  
Author(s):  
Hee-Min Noh
Keyword(s):  
Numerical Simulation ◽  
Numerical Analysis ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
High Speed ◽  
Aerodynamic Noise ◽  
Noise Generation ◽  
Noise Sources ◽  
High Speed Trains ◽  
Boltzmann Method

A pantograph in contact with a catenary for power supply is one of the major aerodynamic noise sources in high-speed trains. To reduce pantograph noise, it is essential to understand the noise generation mechanism of the pantograph. However, it is difficult to determine this mechanism through measurement. Therefore, in this study, the aerodynamic and acoustic performances of a pantograph in a high-speed train were investigated through numerical analysis using the lattice Boltzmann method. First, a real-scaled pantograph was modeled through computer-aided design. Then, the surface and volume meshes of the pantograph model were generated for simulation analysis. Numerical simulation was conducted at a speed of 300 km/h based on the lattice Boltzmann method. Based on the time derivative analysis of flow pressures, it was concluded that the panhead, joint, and base were the dominant noise sources in the pantograph. In particular, various vortexes were generated from the metalized carbon strip of the panhead. The peaks of the sound pressure level propagated from the panhead were 242, 430, and 640 Hz. The noise generation mechanism was analyzed through numerical simulation using noise characteristics.

Prediction of the Aerodynamic Acoustic Power Contribution on Automobile’s Surface Based on Curle’s Integral in Broadband Noise Source Models

2011 ◽  
Vol 317-319 ◽  
pp. 2284-2288
Author(s):  
Zhen Gyu Zheng ◽  
Ren Xian Li
Keyword(s):  
High Speed ◽  
Optimization Design ◽  
Noise Source ◽  
Power Level ◽  
Research Work ◽  
Acoustic Power ◽  
Broadband Noise ◽  
Vehicle Body ◽  
Aerodynamic Noise ◽  
Source Models

The Aerodynamic noise, which is generated by the moving vehicle at high speed, is a kind of broadband noise. This paper dwelled on the Ligthill’s Acoustic Analogy firstly, and applied the realizable k-ε turbulence model to simulate the external steady flow field of automobile, so as to get the distribution characters of statistical turbulence quantities based on the Reynolds-averaged Navier-Stokes (RANS) equation. Then the Curle’s Integral in Broadband Noise Source Models was utilized to predict the local aerodynamic acoustic power contribution on automobile’s surface, which is helpful to the farther research work in the vehicle body optimization design based on aerodynamic noise controlling. The results shows that: The aerodynamic acoustic power contribution regions on surface mainly distribute near the automobile’s head and tail; and the maximum SAPL (Surface Acoustic Power Level) value is up to 83.15 dB in the vicinity of the rear wheel hub when the vehicle speed is 120km/h; the higher the speed of automobile, the more scattered the distribution of main aerodynamic acoustic power on automobile’s surface.

Lärmuntersuchung an PKD-Planfräsern im Leerlauf/Noise on fast rotating face milling cutter in tool running idle

2021 ◽  
Vol 111 (05) ◽  
pp. 349-354
Author(s):  
Alexander Dobrinski ◽  
Thomas Stehle ◽  
Hans-Christian Möhring
Keyword(s):  
High Speed ◽  
Face Milling ◽  
Noise Generation ◽  
German Research Foundation ◽  
High Speed Cutting ◽  
Sound Exposure ◽  
Machine Operators ◽  
Generation Mechanisms ◽  
The University ◽  
Fast Rotating

Die Lärmentstehungsproblematik bei der HSC (High Speed Cutting)-Fräsbearbeitung von Leichtbaumaterialien wie Aluminiumlegierungen und Kunststoffen ist aufgrund der hohen auf Maschinenbediener wirkenden Schallexpositionswerten sehr aktuell. Am Institut für Werkzeugmaschinen (IfW) der Universität Stuttgart wurden Untersuchungen zur Ermittlung der Lärmentstehungsmechanismen im Leerlauf sowie der daraus folgenden Ableitung von Lärmminderungsmaßnahmen an schnell rotierenden Planfräswerkzeugen im Rahmen des von der Deutschen Forschungsgemeinschaft (DFG) geförderten Forschungsprojektes STE 1563/28-1 durchgeführt.   The problem of noise generation during HSC milling of lightweight materials such as aluminium alloys and plastics is highly relevant due to the high levels of sound exposure affecting machine operators. The Institute for Machine Tools at the University of Stuttgart conducted investigations to determine the noise generation mechanisms during tool idling and to derive noise reduction measures on fast rotating face milling tools as part of the research project STE 1563/28-1 funded by the German Research Foundation (DFG).

Sign in / Sign up

Export Citation Format

Share Document