In this work, a flow reversal resonator fitted with a short-circuit duct connecting the inlet and outlet is analysed and used as a tuneable muffler element, aimed to be used use in a semi-active muffler on an IC-engine.
The work done can be divided into 3 main parts. 1), a study of what type of valve that could be used to change the acoustical properties of the short-circuit duct. 2), Design of a flow reversal resonator with a controllable valve as the short-circuit. 3), experimental validation in a flow acoustic test rig.
The flow reversal resonator with a controllable valve as short-circuit is successfully validated to work as tuneable muffler element during laboratory conditions. The same valve concept is simulated in a full scale concept but not validated experimentally on a running IC-engine.
The theory used to describe the acoustics of a flow duct element is also presented together with three simulation techniques and the two microphone technique used to determine the acoustic properties of the investigated flow reversal resonator.
Author: Svanberg, Petter