Insertion loss of a helmholtz resonator in the intake system of internal combustion engines: an experimental and computational investigation

Wide open throttle dynamometer experiments are conducted on a firing 3.0L V6 engine with a narrow-band silencer (Helmholtz resonator) in the induction system. The effect of the silencer in the intake system is studied by performing the experiments both with and without the silencer in an intake pipe connected to a prototype intake manifold with no zip tube and air cleaner, while maintaining the overall length of the intake system. Instantaneous pressure data is acquired at key locations for a number of speeds over the operating range (1000–5000 rpm). The sound attenuation characteristics of the Helmholtz resonator are determined in terms of insertion loss. The results are presented in time-domain, as well as order-domain. The present study also describes an ongoing effort towards employing nonlinear fluid dynamic models in the time-domain for the prediction of acoustic and power performance of internal combustion engines. The model predictions compared to the experiments at a number of locations show reasonable agreement for the instantaneous pressure and sound pressure levels.