Abstract
It is well known that some of sources of noise which radiates from an exhaust pipe of automobile engine exist in the flow field downstream of the pipe end. An unsteady jet issues periodically from the pipe end with shock waves, so that the unsteady jet interacts with them, resulting in the formation of the complicated flow pattern. To clarify the mechanism of noise generation, the flow field downstream of the pipe end is experimentally examined using a shock tube of diaphragmless type. Two shock waves are generated at short intervals of time in the tube. The flow field is visualized by shadowgraph method and different types of density waves are observed. The density wave is considered to be one of the sources of noise.
