Affiliations: Tokyo Metropolitan College of Technology, Tokyo
140-0011, Japan | Tokyo Denki University, Tokyo 101-0054, Japan
Abstract: Noise is generated from a flow field upstream of a shock wave
periodically discharged from a pipe end. A vortex ring and an underexpanded jet
are periodically formed and diffused downstream. To clarify the mechanism of
the noise generation, the flow field was experimentally and numerically
studied. The flow field was visualized mainly by the schlieren method and the
sound pressure of the noise was measured. The pulsatile flow through the pipe
was numerically simulated by Random-Choice Method and using these results as
the boundary condition, the pulsatile jet was simulated by TVD scheme. As a
result, a good qualitative agreement was found between the flow field obtained
by the calculations and that by the experiments. Furthermore, a relation
between the behaviour of the vortex ring and the generation of the noise was
discussed.