This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Directivity Measurements of Low Frequency Sound Field Radiated from an Open Cylindrical Pipe with a Hot Mean Flow
ISSN: 0148-7191, e-ISSN: 2688-3627
Published June 15, 2016 by SAE International in United States
Annotation ability available
Event: 9th International Styrian Noise, Vibration & Harshness Congress: The European Automotive Noise Conference
Radiation of sound from an open pipe with a hot mean flow presents one of the classic problems of acoustics in inhomogeneous media. The problem has been especially brought into focus in the last several decades, in the context of noise control of vehicle exhaust systems and jet engines. However, the reports on the measurements of the radiated sound field are still rare and scattered over different values of subsonic and supersonic flow speeds, cold and hot jets, as well as different sound frequency ranges. This paper focuses on low Mach number values of the mean flow speed and low frequencies of the incident (plane) sound waves inside an unflanged cylindrical pipe with a straight cut. It presents the results of the far-field radiation pattern measurements and compares them with an existing analytical model from the literature. The mean flow inside the pipe reached Mach number values up to 0.25 and temperature up to 300°C. Acoustic measurements were done in an anechoic chamber using a semi-circular microphone array. The plane wave inside the pipe was generated using a low-frequency loudspeaker placed in a side-branch pipe. In general, the results coincide very well with the analytical model, with the exception of refraction effects, such as the occurrence of radiation minimum at the pipe axis (i.e. “the cone of silence”).
CitationMasovic, D., Zotter, F., Nijman, E., Rejlek, J. et al., "Directivity Measurements of Low Frequency Sound Field Radiated from an Open Cylindrical Pipe with a Hot Mean Flow," SAE Technical Paper 2016-01-1822, 2016, https://doi.org/10.4271/2016-01-1822.
- Levine H. and Schwinger J. On the Radiation of Sound from an Unflanged Circular Pipe Physical Review 73 4 383 406 1948 10.1103/PhysRev.73.383
- Munt R. M. The Interaction of Sound with a Subsonic Jet Issuing from a Semi-Infinite Cylindrical Pipe Journal of Fluid Mechanics 83 4 609 640 1977 10.1017/S0022112077001384
- Tiikoja H. , Lavrentjev J. , Rämmal H. and Åbom M. Experimental Investigations of Sound Reflection from Hot and Subsonic Flow Duct Termination Journal of Sound and Vibration 333 3 788 800 2014 10.1016/j.jsv.2013.09.030
- Atvars J. , Schubert L. K. , Grande E. and Ribner H. S. Refraction of Sound by Jet Flow or Jet Temperature UTIAS Technical Note No. 109 May 1965
- Moore C. J. The Role of Shear-Layer Instability Waves in Jet Exhaust Noise Journal of Fluid Mechanics 83 4 609 640 1977 10.1017/S0022112077001700
- Howe M. S. Attenuation of Sound in a Low Mach Number Nozzle Flow Journal of Fluid Mechanics 91 2 209 229 1979 10.1017/S0022112079000124
- Hornikx M. , De Roeck W. and Desmet W. Flow and Geometrical Effects on Radiated Noise from Exhausts Computed by a Hybrid Extended Fourier PSTD Method 17th AIAA/CEAS Aeroacoustics Conference, 2011-2844 Portland, Oregon June 5-8, 2011
- Shi Y. , da Silva A. and Scavone G. Numerical Analysis of the Mean Flow Effect on the Sound Directivity Pattern of culindrical Ducts Proceedings of SMAC 2013 458 464 Stockholm, Sweden July 30 - August 3, 2013
- Bierkens J. Calculation of the Reflection Coefficient of a Jet Pipe with Subsonic Jet Flow project report Eindhoven University of Technology July 2002
- Russo G. P. Aerodynamic Measurements Woodhead Publishing 2011 978-1-84569-992-5
- Peters M. C. A. M. , Hirschberg A. , Reijnen A. J. and Wijnands A. P. J. Damping and Reflection Coefficient Measurements for an Open Pipe at Low Mach and Low Helmholtz Numbers Journal of Fluid Mechanics 256 499 534 1993 10.1017/S0022112093002861
- Witze P. O. Centerline Velocity Decay of Compressible Free Jets AIAA Journal 12 4 417 418 1974 10.2514/3.49262
- Van Der Walt D. C. Measurement Technique to Assess the Acoustic Properties of a Silencer Component for Transient Engine Conditions Journal of Sound and Vibration 243 5 797 821 2001 10.1006/jsvi.2000.3432