Weak Spherical Shock-Wave Transitions of N-Waves in Air with Vibrational Excitation,
TORONTO UNIV DOWNSVIEW (ONTARIO) INST FOR AEROSPACE STUDIES
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The effects of vibrational excitation on shock-wave transitions of weak sperical N-waves were investigated for overpressures below 100 Pa. The spherical N-waves were generated by using sparks and exploding wires as sources in a still-air dome of 40-m diam. The pressure profiles of the N-waves were observed by using high-frequency microphones, which were located at several positions 10-30m from the source. It was found that the measured risetimes of the N-waves for overpressures of 5-30 Pa and half duration of 50-120 microsec were much shorter than the risetime estimated from the theory of plane, fully-dispersed waves with vibrational excitation of oxygen.