A Three-Dimensional Numerical Investigation of Air Pumping Noise Generation in Tires

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
Prashanta Gautam ◽  
Abhilash J. Chandy
Keyword(s):  
Noise Reduction ◽  
Numerical Models ◽  
Fluid Dynamic ◽  
Near Field ◽  
Three Dimensional ◽  
Complex Nature ◽  
Noise Generation ◽  
Vehicle Noise ◽  
Tire Noise ◽  
Generation Mechanisms

Tire noise reduction is an important aspect of overall vehicle noise reduction. However, due to the complex nature of tire noise generation and correlation between various generation mechanisms, it is difficult to isolate, predict, and control tire noise. Air-related noise generation mechanisms in tires are tough to predict experimentally, resulting in the need for an accurate numerical model. Computational fluid dynamics (CFDs) is used here to propose a numerical tool capable of predicting air-pumping noise generation. Slot deformations are prescribed by custom functions instead of using structural solvers and the rotation of tire is represented by using mesh motion and deformation techniques. Near-field and far-field acoustic characteristics are predicted using fluid dynamic equations and acoustic models. The use of various spectral analysis tools show that the proposed model is capable of predicting the high frequency air-pumping noise while also predicting other air-related mechanisms such as pipe resonance, Helmholtz resonance, and rotational turbulence. This study is intended to provide an understanding of the various air-related noise generation mechanisms so that numerical models can be used in the future to predict tire acoustics economically and effectively.

An experimental and computational investigation of air-borne noise generation mechanisms in tires

2018 ◽  
Vol 25 (3) ◽  
pp. 529-537 ◽  
Author(s):  
Prashanta Gautam ◽  
Yousof Azizi ◽  
Abhilash J. Chandy
Keyword(s):  
Spectral Characteristics ◽  
Operating Conditions ◽  
Complex Nature ◽  
Generation Process ◽  
Noise Generation ◽  
Frequency Spectra ◽  
Tire Noise ◽  
Noise Data ◽  
Generation Mechanisms ◽  
Air Pockets

The complex nature of the tire/road noise generation process makes it difficult to isolate and study each mechanism individually. This paper presents an experimental and numerical investigation of air-borne tire noise generation mechanisms for a realistic tire. Experimentally, a single slot is cut into the tire and the noise data are measured and studied. Air-borne noise is isolated by filling the slot with foam and comparing the resulting frequency spectra. Numerically, a previously developed computational fluid dynamics tire noise prediction model is employed to predict the air-borne noise for the same tire, under similar operating conditions. A direct comparison between the experimental and computational results is also presented in terms of pressure time traces and spectral characteristics. Comparisons indicate that the computational model is capable of predicting the noise generated by the air pockets in the tire. While providing a deeper understanding of the causes of air-borne noise, this paper also aims to demonstrate the use of a computational tool that can be used to obtain a reasonably accurate prediction of air-borne tire noise.

scholarly journals The Fluid-Solid Interaction Dynamics between Underwater Explosion Bubble and Corrugated Sandwich Plate

2016 ◽  
Vol 2016 ◽  
pp. 1-21
Author(s):  
Hao Wang ◽  
Yuan Sheng Cheng ◽  
Jun Liu ◽  
Lin Gan
Keyword(s):  
Shock Wave ◽  
Failure Modes ◽  
Sandwich Structures ◽  
Numerical Models ◽  
Near Field ◽  
Three Dimensional ◽  
Underwater Explosion ◽  
Bubble Collapse ◽  
Fe Model ◽  
Wave Load

Lightweight sandwich structures with highly porous 2D cores or 3D (three-dimensional) periodic cores can effectively withstand underwater explosion load. In most of the previous studies of sandwich structure antiblast dynamics, the underwater explosion (UNDEX) bubble phase was neglected. As the UNDEX bubble load is one of the severest damage sources that may lead to structure large plastic deformation and crevasses failure, the failure mechanisms of sandwich structures might not be accurate if only shock wave is considered. In this paper, detailed 3D finite element (FE) numerical models of UNDEX bubble-LCSP (lightweight corrugated sandwich plates) interaction are developed by using MSC.Dytran. Upon the validated FE model, the bubble shape, impact pressure, and fluid field velocities for different stand-off distances are studied. Based on numerical results, the failure modes of LCSP and the whole damage process are obtained. It is demonstrated that the UNDEX bubble collapse jet local load plays a more significant role than the UNDEX shock wave load especially in near-field underwater explosion.

A Computational Fluid Dynamics Model for Investigating Air-Pumping Mechanisms in Air-Borne Tire Noise

2016 ◽  
Vol 44 (3) ◽  
pp. 191-211 ◽  
Author(s):  
Prashanta Gautam ◽  
Abhilash J. Chandy
Keyword(s):  
Stokes Equations ◽  
Road Traffic ◽  
Near Field ◽  
Spectral Characteristics ◽  
Small Scale ◽  
Road Traffic Noise ◽  
Far Field ◽  
Noise Generation ◽  
Tire Noise ◽  
Noise Characteristics

ABSTRACT The reduction in power train noise over the past decade has led to an increased focus in reducing tire/road noise, largely due to the environmental concerns related to road traffic noise in industrial countries. Computational fluid dynamic (CFD) simulations conducted using ANSYS FLUENT are presented here with the objective of understanding air-pumping noise-generation mechanisms due to tire/road interaction. The CFD model employs a large eddy simulation turbulence modeling approach, in which the filtered compressible Navier-Stokes equations are solved to obtain temporally and spatially accurate near-field pressure fluctuations for a two-dimensional (2D) tire geometry with (1) one groove and (2) two grooves. In addition, the Ffowcs-Williams and Hawkings (FW-H) acoustic model is used to predict far-field acoustics. The deformation of the grooves, as the tire rotates, is represented by prescribed sidewall movements. Consequently, the solution to the numerical problem is obtained through a single process, thereby enabling the prediction of small-scale air pumping, horn effect, and far-field acoustics in a single simulation. The acoustic characteristics associated with air pumping are studied through spectral analysis tools, and comparisons show that the additional groove on the horn geometry alters the spectral characteristics of air pumping. Validation of the model is conducted through qualitative and quantitative comparisons with previous studies. These simulations are intended to provide a deeper understanding about the small-scale noise generation as well as the near-field and far-field acoustics, thereby paving the way for the automotive manufacturer to compare a variety of air-related tire noise characteristics without spending time and money for vehicle pass-by tests.

Noise Prediction of Pressure-Mismatched Jets Using Unstructured Large Eddy Simulation

2011 ◽  
Author(s):  
Yaser Khalighi ◽  
Frank Ham ◽  
Parviz Moin ◽  
Sanjiva K. Lele ◽  
Robert H. Schlinker
Keyword(s):  
Large Eddy Simulation ◽  
Turbulent Flow ◽  
Three Dimensional ◽  
Empirical Models ◽  
Nozzle Geometry ◽  
High Fidelity ◽  
Noise Generation ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Generation Mechanisms

It is our premise that significant new advances in the understanding of noise generation mechanisms for jets and realistic methods for reducing this noise can be developed by exploiting high-fidelity computational fluid dynamics: namely large eddy simulation (LES). In LES, the important energy-containing structures in the flow are resolved explicitly, resulting in a time-dependent, three-dimensional realization of the turbulent flow. In the context of LES, the unsteady flow occurring in the jet plume (and its associated sound) can be accurately predicted without resort to adjustable empirical models. In such a framework, the nozzle geometry can be included to directly influence the turbulent flow including its coherent and fine-scale motions. The effects of propulsion system design choices and issues of integration with the airframe can also be logically addressed.

scholarly journals <i>HydrothermalFoam</i> v1.0: a 3-D hydro-thermo-transport model for natural submarine hydrothermal systems

2020 ◽  
Author(s):  
Zhikui Guo ◽  
Lars Rüpke ◽  
Chunhui Tao
Keyword(s):  
Transport Model ◽  
Numerical Models ◽  
Fluid Dynamic ◽  
Pure Water ◽  
Three Dimensional ◽  
Hydrothermal Systems ◽  
Dynamic Simulations ◽  
Flow Models ◽  
Wide Range ◽  
Submarine Hydrothermal Systems

Abstract. Herein, we introduce HydrothermalFoam, a three dimensional hydro-thermo-transport model designed to resolve fluid flow within submarine hydrothermal circulation systems. HydrothermalFoam has been developed on the OpenFOAM platform, which is a Finite Volume based C++ toolbox for fluid-dynamic simulations and for developing customized numerical models that provides access to state-of-the-art parallelized solvers and to a wide range of pre- and post-processing tools. We have implemented a porous media Darcy-flow model with associated boundary conditions designed to facilitate numerical simulations of submarine hydrothermal systems. The current implementation is valid for single-phase fluid states and uses a pure water equation-of-state (IAPWS-97). We here present the model formulation, OpenFOAM implementation details, and a sequence of 1-D, 2-D and 3-D benchmark tests. The source code repository further includes a number of tutorials that can be used as starting points for building specialized hydrothermal flow models. The model is published under the GNU General Public License v3.0.

scholarly journals <i>HydrothermalFoam</i> v1.0: a 3-D hydrothermal transport model for natural submarine hydrothermal systems

2020 ◽  
Vol 13 (12) ◽  
pp. 6547-6565
Author(s):  
Zhikui Guo ◽  
Lars Rüpke ◽  
Chunhui Tao
Keyword(s):  
Transport Model ◽  
Numerical Models ◽  
Fluid Dynamic ◽  
Pure Water ◽  
Three Dimensional ◽  
Hydrothermal Systems ◽  
Dynamic Simulations ◽  
Flow Models ◽  
Wide Range ◽  
Submarine Hydrothermal Systems

Abstract. Herein, we introduce HydrothermalFoam, a three-dimensional hydro-thermo-transport model designed to resolve fluid flow within submarine hydrothermal circulation systems. HydrothermalFoam has been developed on the OpenFOAM platform, which is a finite-volume-based C++ toolbox for fluid-dynamic simulations and for developing customized numerical models that provides access to state-of-the-art parallelized solvers and to a wide range of pre- and post-processing tools. We have implemented a porous media Darcy flow model with associated boundary conditions designed to facilitate numerical simulations of submarine hydrothermal systems. The current implementation is valid for single-phase fluid states and uses a pure-water equation of state (IAPWS-97). We here present the model formulation; OpenFOAM implementation details; and a sequence of 1-D, 2-D, and 3-D benchmark tests. The source code repository further includes a number of tutorials that can be used as starting points for building specialized hydrothermal flow models. The model is published under the GNU General Public License v3.0.

Identification of Tire Noise Generation Mechanisms Using a Roadwheel Facility

1980 ◽  
Author(s):  
Kenneth J. Plotkin ◽  
Mark M. Montroll ◽  
William R. Fuller ◽  
Harvey J. Nozick
Keyword(s):  
Noise Generation ◽  
Tire Noise ◽  
Generation Mechanisms

The influence of belt and tread band stiffness on the tire noise generation mechanisms

1998 ◽  
Vol 103 (5) ◽  
pp. 2919-2919 ◽  
Author(s):  
Wolfgang Kropp ◽  
Krister Larsson ◽  
Stephane Barrelet
Keyword(s):  
Noise Generation ◽  
Tire Noise ◽  
Generation Mechanisms

Numerical Analysis of a Laboratory Centrifugal Pump for the Training of Graduate Engineers

2006 ◽  
Author(s):  
G. Cenci ◽  
M. Pinelli
Keyword(s):  
Numerical Simulation ◽  
Numerical Analysis ◽  
Centrifugal Pump ◽  
Numerical Models ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Industrial Applications ◽  
Basic Knowledge ◽  
Grid Turbulence ◽  
Turbomachinery Design

The up-to-date design of turbomachinery involves the use of three dimensional computational fluid dynamic analyses to match the challenge of the ever increasing speed of product development. Recently, the application of these analyses to turbomachinery, which in past years was confined to specialist fields, has become widespread in many industrial applications. Hence, besides the teaching of traditional methods for turbomachinery design, an important part of modern engineering education is to produce graduates with advanced skills in Computational Fluid Dynamics (CFD) techniques applied to turbomachinery design. Moreover, at this time, these skills should either match the needs of research laboratories or be compatible with industrial needs, since three dimensional numerical calculation is also coming to be seen as a feasible tool in ordinary applications. For these reasons, CFD courses for the training of graduate students have been developed. In this paper, the methodology followed and the work carried out by the students of the course in Fluid Dynamic Design of Turbomachinery held at the University of Ferrara is presented. In particular, three levels of investigation are taken into consideration and presented: (i) focus on the fundamentals to achieve a basic knowledge of a design process based on numerical simulation; (ii) extension to higher level of in-depth analyses of the specific models which could be used in every phase of a numerical simulation; (iii) insight into the specificity of the main thermodynamic and fluid dynamic characteristics of turbomachinery. To achieve this, the numerical analysis of a simple but exhaustive geometry of a centrifugal pump has been carried out and the results obtained are analyzed. In particular, special emphasis is devoted to: (i) the comparison among the numerical models which can be chosen throughout the simulations of turbomachinery (type of grid, turbulence models, rotor/stator interface models) and (ii) the analysis of some of the most important fluid dynamic phenomena, such as, in this case, velocity profiles and jet-and-wake structure.

Three-Dimensional reconstruction of isolated centrosomes by automated electron tomography

1994 ◽  
Vol 52 ◽  
pp. 310-311
Author(s):  
M.B. Braunfeld ◽  
M. Moritz ◽  
B.M. Alberts ◽  
J.W. Sedat ◽  
D.A. Agard
Keyword(s):  
Electron Tomography ◽  
Three Dimensional ◽  
Vital Role ◽  
Complex Nature ◽  
Animal Cells ◽  
Microtubule Organizing Center ◽  
Nucleation Sites ◽  
Dimensional Reconstruction ◽  
Organizing Center ◽  
Resolution Model

In animal cells, the centrosome functions as the primary microtubule organizing center (MTOC). As such the centrosome plays a vital role in determining a cell's shape, migration, and perhaps most importantly, its division. Despite the obvious importance of this organelle little is known about centrosomal regulation, duplication, or how it nucleates microtubules. Furthermore, no high resolution model for centrosomal structure exists.We have used automated electron tomography, and reconstruction techniques in an attempt to better understand the complex nature of the centrosome. Additionally we hope to identify nucleation sites for microtubule growth.Centrosomes were isolated from early Drosophila embryos. Briefly, after large organelles and debris from homogenized embryos were pelleted, the resulting supernatant was separated on a sucrose velocity gradient. Fractions were collected and assayed for centrosome-mediated microtubule -nucleating activity by incubating with fluorescently-labeled tubulin subunits. The resulting microtubule asters were then spun onto coverslips and viewed by fluorescence microscopy.

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