scholarly journals Energy estimation of explosion sound source based on atmospheric sound propagation theory

2021 ◽  
Vol 0 (0) ◽  
pp. 0-0
Author(s):  
◽  
◽  
Keyword(s):  
Sound Source ◽  
Sound Propagation ◽  
Propagation Theory ◽  
Energy Estimation

Synthetic Sound Source Generation for Acoustical Measurements in Turbomachines

2013 ◽  
Author(s):  
Michael Bartelt ◽  
Juan D. Laguna ◽  
Joerg R. Seume
Keyword(s):  
Wind Tunnel ◽  
Sound Source ◽  
Sound Propagation ◽  
Microphone Array ◽  
Sound Field ◽  
Acoustic Mode ◽  
Acoustic Excitation ◽  
Noise Emission ◽  
Noise Sources ◽  
Sound Fields

One of the greatest challenges in modern aircraft propulsion design is the reduction of the engine noise emission in order to develop quieter aircrafts. In the course of a current research project, the sound transport in low pressure turbines is investigated. For the corresponding experimental measurements, a specific acoustic excitation system is developed which can be implemented into the inlet of a turbine test rig and into an aeroacoustic wind tunnel. This allows for an acoustic mode generation and a synthesis of various sound source patterns to simulate typical turbomachinery noise sources such as rotor-stator interaction, etc. The paper presents the acoustical and technical design methodology in detail and addresses the experimental options of the system. Particular attention is paid to the design and the numerical optimization of the acoustic excitation units. To validate the sound generator during operation, measurements are performed in an aeroacoustic wind tunnel. For this purpose, an in-duct microphone array with a specific beamforming algorithm for hard-walled ducts is developed and applied to identify the source locations. The synthetically excited sound fields and the propagating acoustic modes are measured and analyzed by means of modal decomposition techniques. The measurement principles and the results are discussed in detail and it is shown that the intended sound source is produced and the intended sound field is excited. This paper shall contribute to help guide the development of excitation systems for aeroacoustic experiments to better understanding the physics of sound propagation within turbomachines.

Efficient Combustion Noise Simulation of a Gas Turbine Model Combustor Based on Stochastic Sound Sources

2015 ◽  
Author(s):  
Felix Grimm ◽  
Roland Ewert ◽  
Jürgen Dierke ◽  
Gilles Reichling ◽  
Berthold Noll ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Sound Source ◽  
Sound Propagation ◽  
Hybrid Approach ◽  
Particle Method ◽  
Combustion Noise ◽  
Equation Modeling ◽  
Source Modeling ◽  
Sound Sources ◽  
Turbine Model

A gas turbine model combustor is simulated with a hybrid, stochastic and particle-based method for combustion noise prediction with full 3D sound source modeling and sound propagation. Alongside, an incompressible LES simulation of the burner is considered for the investigation of the performance of the hybrid approach. The highly efficient time-domain method consists of a stochastic sound source reconstruction algorithm, the Fast Random Particle Method (FRPM) and sound wave propagation via Linearized Euler Equations (LEEs). In the context of this work, the method is adapted and tested for Combustion Noise (CN) prediction. Monopole sound sources are reconstructed by using an estimation of turbulence statistics from reacting CFD-RANS simulations. First, steady state and unsteady CFD calculations of flow field and combustion of the model combustor are evaluated and compared to experimental results. Two equation modeling for turbulence and the EDM (Eddy Dissipation Model) with FRC (Finite Rate Chemistry) for combustion are employed. In a second step, the acoustics simulation setup for the model combustor is introduced. Selected results are presented and FRPM-CN pressure spectra are compared to experimental levels.

Denoising Weighting Beamforming Method Applied to Sound Source Localization With Airflow Using Microphone Array

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Zhongming Xu ◽  
Kai Tian ◽  
Yansong He ◽  
Zhifei Zhang ◽  
Shu Li
Keyword(s):  
Source Localization ◽  
Sound Source ◽  
Background Noise ◽  
Sound Propagation ◽  
Phase Mismatch ◽  
Sound Source Localization ◽  
Time Averaging ◽  
Iterative Regularization ◽  
Spectral Matrix ◽  
Incoherent Noise

Conventional frequency domain beamforming (FDBF) relies on the measured cross-spectral matrix (CSM). However, in wind tunnel tests, the CSM diagonal is contaminated by the interference of incoherent noise after long-time averaging which leads the source map to poor resolution. Diagonal removal (DR) can suppress the noise in beamforming results via the deletion of CSM diagonal, but this method leads to the underestimation of source levels and some negative powers in source maps. Some advanced methods, such as background subtraction, make use of background noise reference to counteract the effects of contamination; however, the results usually become unreliable, because the background noise is difficult to keep constant in different measurements. Diagonal denoising (DD) beamforming is a recent approach to suppress the contamination effects, but it attenuates the noise suppression performance. To overcome the limitations of the above methods, a new method called denoising weighting beamforming (DWB) is proposed in this study on the basis of CSM DD and an iterative regularization method is applied to solve the acoustical inverse problem. Besides, in order to correct the phase mismatch caused by the influence of flow on sound propagation, the shear flow correction is added before using DWB. Experiments on sound source reconstruction are conducted in the environment with the flow. Acoustics data obtained via this method show the successful removal of incoherent noise and the corrected phase mismatch. Furthermore, the sound source localization results are promising and the proposed method is simple to implement.

SOFTWARE DEVELOPMENT FOR ESTIMATION OF LOW FREQUENCY SOUND PROPAGATION IN GAS GUIDES OF POWER PLANTS TAKING TO ACCOUNT ACTIVE SOUND SOURCES

2020 ◽  
Vol 5 (4) ◽  
pp. 36-44
Author(s):  
A V Vasilyev
Keyword(s):  
Sound Source ◽  
Power Plants ◽  
Sound Propagation ◽  
Combustion Engine ◽  
Source Parameters ◽  
Low Frequency ◽  
Sound Sources ◽  
Software Application ◽  
Frequency Sound ◽  
Exhaust Noise

This paper is devoted to the problems of modelling and calculation of propagation of low frequency sound in gas guides of power plants taking to account active sound sources. The structure of software for prediction and calculation of low-frequency sound propagation in gas guides have described. Software uses four-pole method and takes to account radiation from additional (active) sound course. By using software it is possible to estimate sound source parameters to provide efficient sound attenuation. Examples of software application to calculation of intake and exhaust noise of internal combustion engine are described. The results of calculations show the possibilities of four-pole method software using to design acoustically the parameters of gas guides and mufflers for the different fields of applications.

Low Frequency Measurement by Synchronized Integrating Method and Influence of Reflecting Object

1983 ◽  
Vol 2 (2) ◽  
pp. 85-95 ◽  
Author(s):  
H. Fukuhara ◽  
T. Ohkuma
Keyword(s):  
Sound Source ◽  
Integral Method ◽  
Sound Propagation ◽  
Low Frequency ◽  
Noise Pollution ◽  
Frequency Measurement ◽  
Quantitative Investigation ◽  
Frequency Sound ◽  
Measurement And Analysis ◽  
Reflecting Surfaces

Concern over noise pollution led to the development of methods for making environmental assessments. At the same time, the need arose for methods to measure low frequency sound and clarify propagation conditions. The main objective of this research was to investigate low frequency sound propagation conditions and the problems associated with measurement and analysis. We also studied the characteristics of low frequency sound (below 100 Hz) near reflecting surfaces and developed a technique for positioning the measurement microphones. Additionally we found it necessary to develop a new measurement method we call “the synchronized integral” method. A theoretically perfect point sound source was needed for the measurements. To satisfy this need, we constructed a source for quantitative investigation and measurements were made at distances up to 100 m from the sound source. Analysis of the data we collected clarified the following phenomena: −6 dB/-doubling distance (d.d) attenuation is not reached; frequency and microphone height influence attenuation; measurements taken near the ground are most stable; superposition influence occurs at frequencies above 125 Hz.

scholarly journals A Sound Source Localization Device Based on Rectangular Pyramid Structure for Mobile Robot

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Guoliang Chen ◽  
Yang Xu
Keyword(s):  
Mobile Robot ◽  
Source Localization ◽  
Sound Source ◽  
Sound Propagation ◽  
Estimation Method ◽  
Time Delay Estimation ◽  
Sound Source Localization ◽  
Iteration Algorithm ◽  
Time Space ◽  
Pyramid Structure

A sound source localization device based on a multimicrophone array with the rectangular pyramid structure is proposed for mobile robot in some indoor applications. Firstly, a time delay estimation method based on the cross-power spectral phase algorithm and a fast search strategy of peak value based on the geometric distribution of microphones are developed to estimate the sound propagation delay differences between two microphones. Moreover, a rejection strategy is presented to evaluate the correctness of the delay difference values. And then, the device’s geometric equations based on the time-space mapping relationship are established to calculate the position of the sound source. For fast solving the equations, the multimicrophone array space is divided into several subspaces to narrow the solution range, and Newton iteration algorithm is introduced to solve the equations, while its solution is evaluated by an evaluation mechanism based on coordinate thresholds. Finally, some experiments are carried out to verify the performance of the device, of which the results show that the device can achieve sound source localization with a high accuracy.

The Influence of the Shape Space on the Scattering of the Sound Energy

2013 ◽  
Vol 855 ◽  
pp. 237-240
Author(s):  
Alena Pernišová ◽  
Dušan Dlhý
Keyword(s):  
Sound Source ◽  
Sound Propagation ◽  
Shape Space ◽  
Limited Range ◽  
Sound Level ◽  
Sound Sources ◽  
Sound Energy ◽  
Empty Area ◽  
The Way

The sound level adjacent to the sound sources is mainly characterized by the straight sound. The dispersion sound ratio is increasing with distance increasing and within the limited range round the sound source, the sound level is higher, in the area with dispersion bodies even higher than in an empty area. The laws of sound propagation in empty areas are derived on classical geometric base. The laws of sound propagation in large areas with dispersion objects are also derived from these laws complemented with the Kuttruff ́s equation of reverberation process in media with dispersion bodies. Simultaneously the sound energy is according to the purpose divided into the straight sound and the reverberation. The straight sound is the energetic ratio of sound, that is during the way to destination not dispersed and the propagation laws are equal to empty areas propagation laws are equal to empty areas propagation laws. The dispersed sound is the ratio of sound energy that reaches the destination after one or more reflections. The energy result is then the sum of densities of dispersion and straight sound.

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