Acoustical Analysis Applied to Internal Combustion Engine Exhaust Systems of Conical Form

Abstract

In the following analysis the variation of the charging capacity of a small two-stroke motor-cycle engine is utilized to assess the non-steady flow characteristics of conical exhaust pipes having different length and divergence.

The performance of the engine under the most favourable conditions is applied to determine the natural frequency of exhaust ducts fitted with conical portions.

The experimental data yielded are compared with theoretical computations based on acoustical treatments and inspection of the results obtained supports the conclusion that the ports behave as a partly, and not as a fully, closed end as commonly accepted.