Analysis and Experimental Study of the Mean Flow Effect on the Sound Transmission Through a Cylindrical Shell of an Automobile Muffler

2001 ◽  
Author(s):  
Joon-Hyun Lee ◽  
J. Kim ◽  
Vasudeva Kothamasu
Keyword(s):  
Experimental Study ◽  
Cylindrical Shell ◽  
Sound Transmission ◽  
Mean Flow ◽  
Flow Effect ◽  
The Mean

scholarly journals Experimental study on the mean flow characteristics of a supersonic multiple jet configuration

2021 ◽  
Vol 108 ◽  
pp. 106377
Author(s):  
Mohammed Faheem ◽  
Aqib Khan ◽  
Rakesh Kumar ◽  
Sher Afghan Khan ◽  
Waqar Asrar ◽  
...  
Keyword(s):  
Experimental Study ◽  
Flow Characteristics ◽  
Mean Flow ◽  
The Mean

Flow Induced Aerodynamic Noise Analysis of Perforated Tube Mufflers

2012 ◽  
Vol 29 (2) ◽  
pp. 225-231 ◽  
Author(s):  
C.-N. Wang ◽  
C.-C. Tse ◽  
S.-C. Chen
Keyword(s):  
Transmission Loss ◽  
Noise Analysis ◽  
Helmholtz Resonator ◽  
Aerodynamic Noise ◽  
Mean Flow ◽  
Flow Effect ◽  
Flow Induced Noise ◽  
The Mean ◽  
Cfd Method ◽  
Perforated Tube

AbstractDespite the analysis of muffler performance for many years, most works focus mainly on reducing inlet sound and fail to consider the flow effect. Most of their results correlate well with the experimental measurements. Subsequent works have considered the mean flow effect. Owing to Doppler's effect, transmission loss curve of the muffler will shift in its corresponding frequency. However, the correlation is worse than the experimental results since the flow induced noise does not include in the analysis. This work elucidates how flow induced noise affects muffler performance by analyzing a uniform flow that passes through perforated mufflers. The flow field is calculated with the CFD method, followed by evaluation of the aerodynamic noise based on the simulation results. Additionally, the procedure is simplified by computing and comparing only the total sound power induced by the flow in the muffler interior. Two muffler types, Helmholtz resonator and plug perforated tube muffler, are analyzed and discussed.

Investigation on sound transmission through thick-wall cylindrical shells using 3D- theory of elasticity in the presence of external and mean air-gap flow

2016 ◽  
Vol 24 (5) ◽  
pp. 975-1000 ◽  
Author(s):  
K Daneshjou ◽  
R Talebitooti ◽  
A Tarkashvand
Keyword(s):  
Cylindrical Shell ◽  
Mach Number ◽  
Transmission Loss ◽  
Equations Of Motion ◽  
Sound Transmission ◽  
Theory Of Elasticity ◽  
Air Gap ◽  
Thick Wall ◽  
Mean Flow ◽  
Double Wall

This paper studies the effects of an external mean flow and an internal air-gap mean flow on sound transmission through a double-wall thick cylindrical shell. Due to the major influence of some effective terms such as membrane, bending, transverse shearing and rotational inertia on thick-walled shell, three-dimensional theory of elasticity is used to obtain the governing equations of motion. Therefore, Newton’s second law is utilized to develop the equilibrium equations for an infinitesimal element in cylindrical coordinates. Then, the equations of motion related to the circular hollow cylinders are solved using Helmholtz potentials for arbitrary values of physical and geometrical parameters. In addition, by coupling of both inner and outer shells, a modal transfer matrix is created. This modal matrix stands for the global dynamic equilibrium of the double-wall cylinder. Moreover, the sound transmission Loss of the double-wall cylinder excited by an acoustic oblique plane wave with two angles of incident (i.e. elevation and azimuth angles) is predicted. Due to lack of studies in the field of sound transmission through the thick-walled shell, the results obtained in this study are compared with those from other researchers for a thin cylindrical shell. These results indicate an excellent agreement in comparison with each other. Furthermore, the results reveal that with thickening of the shell, critical and coincidence frequencies are getting closer to ring frequency. Moreover, the effects of external and air-gap flows on TL behave in similar way whereas the Mach number is positive. In addition, an improvement of transmission loss can be found whereas the Mach number is negative; particularly this enhancement is more specified for the external flow. Finally, the results indicate that where both external and air-gap fluids simultaneously flow in opposite directions [Formula: see text] the TL is significantly enhanced. However, for the case where these two fluids flow in the same direction [Formula: see text] the TL is decreased.

scholarly journals EXPERIMENTAL STUDY OF THE INLET FLOW IN A NON-PREMIXED COMBUSTION CHAMBER

2020 ◽  
Vol 19 (1) ◽  
pp. 72
Author(s):  
B. P. Trevisan ◽  
W. M. C. Dourado
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Experimental Study ◽  
Combustion Chamber ◽  
Equivalence Ratio ◽  
Premixed Combustion ◽  
Laser Doppler Velocimeter ◽  
Mean Flow ◽  
Inlet Flow ◽  
The Mean

The evaluation, validation and development of the models used in computation fluid dynamics requires the availability of experimental data for which the boundary conditions, especially the conditions of the inlet flow, are well defined. Laser diagnostics techniques provide experimental data used in computational fluid dynamics and are a powerful tool for measurements of the mean properties and fluctuations of the turbulent flow because they are non-intrusive methods, with high repetition rate and high spatial and temporal resolution. Therefore, in the present work an experimental study of the inlet flow (inert and combusting flows) in a non-premixed combustion chamber is presented. The velocity measurements were carried out using a laser Doppler velocimeter at the entrance region of the combustion chamber. An asymmetry on the mean flow and an increase on the total velocity fluctuations with the increase of the equivalence ratio was observed. The major effect on the increase of the equivalence ratio was a presence of a coherent movement on large scales associated to the flame brush dynamics.

Sign in / Sign up

Export Citation Format

Share Document