Author(s)

Keita Ozawa¹, Takayuki Yamagata², Nobuyuki Fujisawa^2,3

¹Graduate School of Science and Technology, Niigata University, Niigata, Japan.
²Department of Mechanical Engineering, Niigata University, Niigata, Japan.
³Department of Mechanical Engineering, Shinshu University, Nagano, Japan.

The three-dimensional visualization of flow and screech-tone emission from an underexpanded circular jet is first investigated experimentally using high-speed cross-schlieren imaging and microphone measurements in the cross-sectional planes along the jet axis. This experimental technique allows the visualization of the shock-cell structure, directivity of sound intensity, and frequency spectrum in the cross-sectional planes of the screeching jet. The high-speed cross-schlieren observation of the screeching jet shows the occurrence of an asymmetrical shock-cell structure that is generated by the flapping mode in the screeching jet. This contributes to the generation of a screech tone propagating upstream along the jet axis and non-uniform sound intensities around the jet in circumferential direction. These observations by high-speed cross-schlieren imaging were validated by the microphone measurements.

Screech Tone, Aeroacoustics, Directivity, Frequency Spectrum, Underexpanded Circular Jet, Schlieren Imaging

Ozawa, K. , Yamagata, T. and Fujisawa, N. (2022) Three-Dimensional Visualization of Shock Cell Structure and Screech Tone Emission in Underexpanded Circular Jet. Journal of Flow Control, Measurement & Visualization, 10, 1-11. doi: 10.4236/jfcmv.2022.101001.