NOISE ABATEMENT ON DIESEL LOCOMOTIVES. EXHAUST SILENCERS ON RAILED DIESEL VEHICLES

The exhaust gas of large diesel engines still contains an appreciable amount of energy, part of which is noticed as exhaust noise. A sound level varying between 110 and 115 dB(A) has been measured at an unsilenced exhaust and the contribution of noise of this level to the ambient noise of a diesel locomotive is rather unfavourable. Damping of the exhaust noise is therefore a matter of some urgency. Requirements to be met by exhaust silencers arise from the field of physics, in the field of mechanical design and construction and in that of economics. It is held that an exhaust silencer ought to obtain a noise reduction of 15 to 20 dB(A) in the exhaust flow, so that the noise level at the outlet of the exhaust pipe should not exceed, even in the most adverse conditions, a maximum value of 95 to 105 dB(A). The exhaust silencer ought not therefore to be considered in isolation as a separate unit, but as an essential part co-operating in the performance of a diesel locomotive. The exhaust silencers used in European diesel rail vehicles are listed in a table. From this it can be seen that the silencers in use are based on only three principles: reflection, resonance and absorption; the theories on which these principles are based are described in this report. Experience has shown that silencers which are theoretically based solely on one of these principles do not give optimum silencing. An exception is the jacketed tube absorption silencer. Optimum silencing can only be obtained by combining two or more of the basic principles. The development of new silencers for a given type of vehicle can therefore be based less on theoretical calculation than on empirical methods guided by theory. From the theoretical possibilities six silencer systems were worked out and these were related to the requirements of the different types of locomotive. From this it was possible to produce tabular recommendations for the design of diesel locomotives, from which the most suitable silencer may be selected in practically all cases. So far, the space generally available for the installation of exhaust silencers is, however, too small and consequently reduces their efficieny. Future designs should provide the necessary space for fitting exhaust silencers.

• Supplemental Notes:
  • Restrictions on the use of this document are contained in the explanatory material.
• Corporate Authors:

  International Union of Railways

  Office of Research and Experiments
  Utrecht,   Netherlands 
• Publication Date: 1967-3

Media Info

• Features: Appendices; Figures;
• Pagination: 34 p.

Subject/Index Terms

• TRT Terms: Diesel engines; Diesel locomotives; Exhaust system components; Noise; Noise control
• Old TRIS Terms: Diesel engine noise; Exhaust silencers; Noise attenuation; Question b104
• Subject Areas: Environment; Railroads;

Filing Info

• Accession Number: 00053139
• Record Type: Publication
• Source Agency: International Union of Railways
• Report/Paper Numbers: B104/RP 1/E Intrm Rpt.
• Files: TRIS
• Created Date: Jul 13 1976 12:00AM