Hostname: page-component-78c5997874-8bhkd Total loading time: 0 Render date: 2024-11-17T21:22:31.722Z Has data issue: false hasContentIssue false
  • English
  • Français

Experimental and Numerical Study on a Straight Exhaust Pipe

Published online by Cambridge University Press:  07 December 2011

S.-M. Liang  and
C.-J. Wang
S.-M. Liang*
Affiliation:
Department of Computer Application Engineering, Far East University, Tainan, Taiwan 74448, R.O.C.
C.-J. Wang
Affiliation:
Department of Mechanical Engineering, Far East University, Tainan, Taiwan 74448, R.O.C.
*
*Professor, corresponding author
Get access

Abstract

In this study, radiated noise is investigated by experimental and numerical methods for a straight exhaust pipe of diameter 23mm that replaces the original exhaust pipe of a motorcycle of EZ 125cc provided by Kwang Yang Motor Co. In experiment, temperature, pressure and flow speed of the exhausted gas have been measured for different engine speeds ranging from 3000-5000rpm without loading. Sound pressure levels (SPL) at a distance of 0.5m from the exhaust pipe exit for different inclination angles (0° ∼ 90°) were recorded and compared with the result of simulation. In numerical simulation, a high-resolution 5th-order Euler solver was used and conducted on a parallel computation system with a cluster of 4 personal computers with dual processors. It is found that the back-and-forth reflection of expansion waves inside the pipe due to the shock wave diffraction around the pipe exit is the mechanism of radiating sound waves from the exhaust pipe. The numerical result shows the exhausted-gas flow with complicated vortex rings and its associated acoustic field. The acoustic field indicates that there are three sound lobes with different directivities for the engine speed of 4000rpm.

Keywords

Blast waveVortex ringEuler equationsSound pressure levelRadiated noise
Type
Articles
Information
Journal of Mechanics , Volume 27 , Issue 4 , December 2011 , pp. 597 - 605
Copyright
Copyright © The Society of Theoretical and Applied Mechanics, R.O.C. 2011

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1. “Standard of Noise Control for Automotive Vehicles,” Environmental Protection Administration, Taiwan, (2008).Google Scholar
2.Lighthill, M. J., “On Sound Generated Aerodynamically. I. General Theory,” Proceedings of the Royal Society of London. Series A, 211, pp. 564–587 (1952).Google Scholar
3.Kim, H. D. and Setoguchi, T., “Study of the Discharge of Weak Shocks from an Open End of a Duct,” Journal of Sound and Vibration, 226, pp. 1011–1028 (1999).CrossRefGoogle Scholar
4.Higashima, J. and Iwamoto, J., “Experimental Study of Exhaust Noise Generated by Pulsating Flow downstream of Pipe End,” JSAE Review, 20, pp. 73–79 (1999).CrossRefGoogle Scholar
5.Endo, M., Futagami, Y. and Iwamoto, J., “Relation Between the Flow Pattern Downstream of Duct and the Noise,” JSAE Review, 21, pp. 125–132 (2000).CrossRefGoogle Scholar
6.Chen, H. and Liang, S. M., “Planar Blast/Vortex Interaction and Sound Generation,” AIAA Journal, 40, pp. 2298–2304 (2002).CrossRefGoogle Scholar
7.Inoue, O. and Hattori, Y., “Sound Generation by Shock-Vortex Interactions,” Journal of Fluid Mechanics, 380, pp. 81–116 (1999).CrossRefGoogle Scholar
8.Liang, S. M. and Lo, C. P., “Shock/Vortex Interactions Induced by Blast Waves,” AIAA Journal, 41, pp. 1341–1346 (2003).CrossRefGoogle Scholar
9.Liang, S. M., Chung, W. T. and Chen, H., “Numerical Investigation of Reflected Shock/Vortex Interaction near an Open-ended Duct,” AIAA Journal, 43, pp. 349–356 (2005).CrossRefGoogle Scholar
10.Kim, H.-D., Kweon, Y.-H. and Setoguchi, T., “A Study of the Weak Shock Wave Propagating through an Engine Exhaust Silencer System,” Journal of Sound and Vibration, 275, pp. 893–915 (2004).CrossRefGoogle Scholar
11.Gabard, G. and Astley, R. J., “Theoretical Model for Sound Radiation from Annular Jet Pipes: Farand Near-field Solutions,” Journal of Fluid Mechanics, 549, pp. 315–341 (2006).CrossRefGoogle Scholar
12.Gabard, G., “Near- to Far-field Characteristics of Acoustic Radiation Through Plug Flow Jets,” Acoustical Society of America, 1124, pp. 2755–2766 (2008)CrossRefGoogle Scholar
13.Demir, A. and Rienstra, S. W., “Sound Radiation from an Annular Duct with Jet Flow and a Lined Centerbody,” 12th AIAA/CEAS Aeroacoustics Conference, 8-10 May, 2006, Cambridge, MA. USA, AIAA Paper 2006-2718.Google Scholar
14.Jiang, G.-S. and Shu, C.-W., “Efficient Implementation of Weighted ENO Schemes,” Journal of Computational Physics, 126, pp. 202–228 (1996).CrossRefGoogle Scholar
15.Thompson, W., “Time Dependent Boundary Conditions for Hyperbolic Systems,” Journal of Computational Physics, 68, pp. 1–24 (1987).CrossRefGoogle Scholar
16.Chung, W. T., “Analysis of the Flow Field and Noise Generation Mechanism inside and near the Exit of a Vehicle's Exhaust Pipe,” Department of Aeronautics and Astronautics, National Cheng Kung University, p. 80 (2007).Google Scholar