This study investigates homogeneous isotropic turbulence generated by the interaction of multiple supersonic jets. Particle Image Velocimetry (PIV) was employed to measure the velocity field in the downstream region of the jets. The skewness of the streamwise velocity gradient was evaluated to examine the characteristics of small-scale turbulence. The measured skewness values were compared with existing data for incompressible turbulence and with results from direct numerical simulations (DNS) of decaying turbulence generated by both subsonic and supersonic jet interactions. The present results show that the magnitude of the skewness is smaller than that in incompressible turbulence, consistent with the trend observed in DNS of supersonic cases. The Taylor-scale Reynolds number in the present experiment was sufficiently high, suggesting that the observed changes are attributed to compressibility effects rather than low-Reynolds-number effects. These findings indicate that compressibility significantly alters the statistical properties of small-scale turbulence.
KUWABARA et al. (Wed,) studied this question.