Dynamic responses for inhomogeneous hydrogen deflagrations in a 7 m3 box-type chamber with a vent: Effects of ignition position and equivalent volume concentration

Abstract

The aim of this paper is to investigate the effects of ignition position and equivalent volume concentration C‾H2 on dynamic responses for vented inhomogeneous hydrogen deflagrations in a 7 m3 chamber. The results indicate that the narrow-band and wide-band processes of overpressure signals are formed during Helmholtz-type and thermo-acoustic oscillations, respectively. The displacement response depending on C‾H2 is characterized by the weak vibration or a sharp increase. The acceleration impulsive response is dominated by the forced vibration component with the high-frequency and high-amplitude, while the acceleration dynamic response is dominated by the free vibration component with the low frequency and low amplitude. The high-frequency component and frequency overlapping in structural responses become more significant with the increase of C‾H2. Structural responses generated by bottom ignition are the largest due to the most violent thermo-acoustic oscillation induced by a coupled flame structure of deflagration flame and jet fire.