scholarly journals Numerical Analysis of Aeroacoustic Phenomena Generated by Truck Platoons

2021 ◽  
Vol 13 (24) ◽  
pp. 14073
Author(s):  
Władysław Hamiga ◽  
Wojciech Ciesielka
Keyword(s):  
Sound Pressure ◽  
Sound Field ◽  
Field Tests ◽  
Turbulence Models ◽  
Transport Systems ◽  
Intelligent Transport ◽  
Eddy Simulation ◽  
Moving Vehicles ◽  
Sound Pressure Levels ◽  
Computational Fluid Dynamics Cfd

In recent years there has been dynamic progress in the development of fully autonomous trucks and their combination and coordination into sets of vehicles moving behind each other within short distances, i.e., platooning. Numerous reports from around the world present significant benefits of platooning for the environment due to reduced emissions, reduced fuel costs, and improved logistics in the transport industry. This paper presents original aerodynamic and aeroacoustic studies of identical truck column models. They are divided into four main stages. In the first, a truck model and three columns of identical trucks with different distances between the vehicles was made and tested using computational fluid dynamics (CFD). Two turbulence models were used in the study: k−ω shear stress transport (SST) and large eddy simulation (LES). The aim of the work was to determine the drag coefficients for each set of vehicles. The second stage of work included determination of sound field distributions generated by moving vehicles. Using the Ffowcs Williams–Hawkings (FW-H) analogy, the sound pressure levels were determined, followed by the sound pressure levels A. In order to verify the correctness of the work carried out, field tests were also performed and additional acoustic calculations were carried out using the NMPB-Routes-2008 and ISO 9613-2 models. Calculations were performed using SoundPlan software. The performed tests showed good quality of the built aerodynamic and aeroacoustic models. The results presented in this paper have a universal character and can be used to build intelligent transport systems (ITSs) and intelligent environmental management systems (IEMSs) for municipalities, counties, cities, and urban agglomerations by taking into account the platooning process.

Electroacoustic Calibration for Sound Field Warble Tone Thresholds

1987 ◽  
Vol 52 (4) ◽  
pp. 388-392 ◽  
Author(s):  
Robyn M. Cox ◽  
Virginia A. McCormick
Keyword(s):  
Sound Pressure ◽  
Sound Field ◽  
Critical Distance ◽  
Sound Fields ◽  
Significant Difference ◽  
Sound Pressure Levels ◽  
Modulation Parameter ◽  
Test Position ◽  
Parameter Values

Walker, Dillon, and Byrne (1984) suggested reference equivalent threshold sound pressure levels (RETSPLs) for warble tones with specific modulation parameter values audited from a test position at the critical distance in a semireverberant sound field. This study evaluated these RETSPLs in two typical audiometric rooms and with typically encountered FM tones. Thresholds were measured under earphones and in two sound fields for 6-11 normal hearers at six test frequencies. Results indicated that there was a small but statistically significant difference between earphone and sound field thresholds in 4 of 24 comparisons. However, in both sound fields, 99% of the sound field thresholds were within 10 dB of the earphone thresholds. It is concluded that these RETSPLs are appropriate for electroacoustic calibration of sound field warble tones similar to those used in this study.

Investigation of turbulence-induced quadrupole source acoustic characteristics of a three-dimensional hydrofoil

2020 ◽  
Vol 34 (14) ◽  
pp. 2050145
Author(s):  
Rennian Li ◽  
Wenna Liang ◽  
Wei Han ◽  
Hui Quan ◽  
Rong Guo ◽  
...  
Keyword(s):  
Vortex Shedding ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Three Dimensional ◽  
Sound Field ◽  
Leading Edge ◽  
Pressure Level ◽  
Acoustic Characteristics ◽  
Eddy Simulation ◽  
Unsteady Fluid

In order to investigate the turbulence-induced acoustic characteristics of hydrofoils, the flow and sound field for a model NH-15-18-1 asymmetric hydrofoil were calculated based on the mixed method of large eddy simulation (LES) with Lighthill analogy theory. Unsteady fluid turbulent stress source around the hydrofoil were selected as the inducements of quadrupole sound. The average velocity along the mainstream direction was calculated for different Reynolds numbers [Formula: see text]. Compared to experimental measurements, good agreement was seen over a range of [Formula: see text]. The results showed that the larger the [Formula: see text], the larger the vortex intensity, the shorter the vortex initial shedding position to the leading edge of the hydrofoil, and the higher the vortex shedding frequency [Formula: see text]. The maximum sound pressure level (SPL) of the hydrofoil was located at the trailing edge and wake of the hydrofoil, which coincided with the velocity curl [Formula: see text] distribution of the flow field. The maximum SPL of the sound field was consistent with the location of the vortex shedding. There were quadratic positive correlations between the total sound pressure level (TSPL) and the maximum value of the vortex intensity [Formula: see text] and velocity curl, which verified that shedding and diffusion of vortices are the fundamental cause of the generation of the quadrupole source noise.

EXPERIMENTAL STUDIES ON THE NOISE AND VIBRATION OF A SPECIAL BORING MACHINE DUE TO FORMATION OF THE OPERATOR´S WORKPLACE SOUND FIELD

Akustika ◽  
2019 ◽  
Vol 34 ◽  
pp. 100-103
Author(s):  
Alexander Shashurin ◽  
Marat Goguadze ◽  
Anna Lubianchenko
Keyword(s):  
Theoretical Analysis ◽  
Sound Pressure ◽  
Experimental Studies ◽  
Sound Radiation ◽  
Sound Field ◽  
Noise Levels ◽  
Noise And Vibration ◽  
Measurement Results ◽  
Sound Pressure Levels ◽  
Excessive Noise

The purpose of this study is to measure the octave sound pressure levels and vibrations of a boring machine. A theoretical analysis of the sound pressure levels near the boring machine is performed. The measurement results are given. It was found that the workplace sound pressure levels exceed the sanitary standards, which suggests that the excessive noise levels are due to the exposure to the cutter sound radiation and the axis being machined.

Numerical Prediction of Bare and Straked Cylinder VIV

2006 ◽  
Author(s):  
Yiannis Constantinides ◽  
Owen H. Oakley
Keyword(s):  
Turbulence Models ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Numerical Studies ◽  
Vortex Induced Vibrations ◽  
Computational Fluid Dynamics Cfd ◽  
Offshore Industry ◽  
High Reynolds ◽  
Cfd Method

The prediction of deepwater riser Vortex Induced Vibrations (VIV) is one of the most challenging areas in the offshore industry. Numerous experimental and numerical studies have been performed in an effort to improve the understanding and prediction of cylinder VIV behavior. This paper presents the numerical simulation of rigid circular sections, both bare and fitted with strakes, using a second order accurate finite element computational fluid dynamics (CFD) method. Two turbulence models are examined: the Spalart-Allmaras Reynolds Averaged Navier Stokes (RANS) and the Detached Eddy Simulation (DES). Pragmatic high Reynolds number simulations of fixed and moving cylinders are presented and compared with laboratory experiments. Flow visualization provides insights on how strakes mitigate VIV. Comparisons between RANS and DES results are also presented and discussed.

scholarly journals Aeroaocustic Numerical Analysis of the Vehicle Model

2020 ◽  
Vol 10 (24) ◽  
pp. 9066
Author(s):  
Władysław Marek Hamiga ◽  
Wojciech Bronisław Ciesielka
Keyword(s):  
Sound Pressure ◽  
Negative Impact ◽  
Fast Fourier Transformation ◽  
Validation Process ◽  
Road Vehicles ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Numerical Tools ◽  
Computational Fluid Dynamics Cfd ◽  
Comparison Criteria

Understanding local phenomena connected with airflow around road vehicles allows to reduce the negative impact of transportation on the environment. This paper presents using numerical tools for Computational Fluid Dynamics (CFD) and Computational AeroAcoustic (CAA) calculation. As a model for simulation, simplified car geometry is used, which is known in the research community as an Ahmed body. The study is divided into two main parts: a validation process and a CAA analysis using the Ffowcs Williams–Hawkings (FW-H) analogy. Research is performed using k−ω Shear Stress Transport (SST) and the Large Eddy Simulation (LES) turbulence model. To compare results with other authors’ studies, three different comparison criteria are introduced: a drag coefficient for different velocities, characteristic flow structure, and velocity profiles. The CAA analysis is presented using colormaps and Fast Fourier Transformation (FFT). The methods used in this work allow visualizing the acoustic field around reference geometry and determining the frequency range for which the A-weighted sound pressure level is the highest.

scholarly journals Optimization of Ultrasonic Acoustic Standing Wave Systems

Actuators ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 9
Author(s):  
Paul Dunst ◽  
Tobias Hemsel ◽  
Peter Bornmann ◽  
Walter Littmann ◽  
Walter Sextro
Keyword(s):  
Boundary Conditions ◽  
Wave Field ◽  
Standing Wave ◽  
Sound Pressure ◽  
Sound Field ◽  
Metal Powders ◽  
Good Efficiency ◽  
Acoustic Standing Wave ◽  
Standing Wave Field ◽  
Sound Pressure Levels

Ultrasonic acoustic standing wave systems find use in many industrial applications, such as sonochemical reactions, atomization of liquids, ultrasonic cleaning, and spray dry. In most applications, highest possible sound pressure levels are needed to achieve optimum results. Until now, the atomization of liquids is limited to fluids with low viscosity, as systems generating sufficient sound pressure for atomizing fluids with higher viscosities are often not marketable due to their low throughput or high costs. For the production of polymer or metal powders or the dispensing of adhesives, highest sound pressures should be achieved with systems in suitable size, with good efficiency and at low cost but without contamination of sonotrodes and reflectors by the dispersed media. An alternative to the use of more powerful transducers is increasing the intensity of the acoustic standing wave field by optimizing the boundary conditions of the acoustic field. In most existing standing wave systems a part of the radiating sound waves does not contribute to the process, as the waves spread into the wrong direction or wipe themselves out due to interference. In order to obtain maximum sound pressure amplitudes in the standing wave field, all waves should be trapped between the sonotrode and the reflector. In addition, the resonance condition should be met for all radiated waves. These conditions can be fulfilled by optimizing the shapes of sonotrode and resonator as well as the distance between them. This contribution reports on a model, which is able to simulate the sound field between a transducer surface and a reflector. Using a linear finite-element model, the boundary conditions of the standing wave system are optimized. Sound pressure levels of the standing wave field are calculated for different shapes of reflectors and boundary conditions like the distance between the transducer and the reflector. The simulation results are validated by sound-field measurements via refracto-vibrometry and a microphone. Finally, optimization guidelines for the generation of high-intensity acoustic standing wave fields are shown and verified by measurements.

Selection of Suitable Turbulence Models for Numerical Modelling of Hydrocyclones

2011 ◽  
Vol 6 (1) ◽  
Author(s):  
Mohsen Karimi ◽  
Guven Akdogan ◽  
Ali Dehghani ◽  
Steven Bradshaw
Keyword(s):  
Swirling Flow ◽  
Turbulence Models ◽  
Reynolds Stress Model ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Boussinesq Hypothesis ◽  
Large Eddy ◽  
Comprehensive Survey ◽  
Computational Fluid Dynamics Cfd ◽  
Les Model

The capability of Computational Fluid Dynamics (CFD) alternates the interest of researcher from the empirical models into the numerical approaches for studying hydrocyclones. This paper presents a comprehensive survey on the influences of turbulence model options in the 3D simulation of the hydrocyclone flow pattern. The required grid resolution was selected through a grid independency study. Four categories of turbulence models involving models based on the Boussinesq hypothesis, the Reynolds Stress Model (RSM), the Large Eddy Simulation (LES) model, and the Detached Eddy Simulation (DES) model were investigated for prediction of velocity components within the hydrocyclone. The methodology was validated by experimental data. The results confirm that both RSM and LES models are efficient turbulent model choices for the simulation of swirling flow of hydrocyclones.

Earphone versus Sound‐Field Threshold Sound‐Pressure Levels for Spondee Words

1966 ◽  
Vol 39 (1) ◽  
pp. 125-133 ◽  
Author(s):  
Tom W. Tillman ◽  
Robert M. Johnson ◽  
Wayne O. Olsen
Keyword(s):  
Sound Pressure ◽  
Sound Field ◽  
Sound Pressure Levels
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