Objectives  In order to study the influence rule of JWL Equation of State(JWL-EOS)and its equivalent polytropic EOS on internal explosion parameters.

  Methods  An independently developed procedure was used to carry out the numerical calculation of explosive blasting process in the cabin. Firstly, the influence rule of different values of parameter ω in the JWL-EOS and the specific heat ratio of ambient gas on the calculated explosion parameters was discussed. Secondly, based on the JWL-EOS, the way to determine parameters in the equivalent polytropic EOS of gas was proposed, and the feasibility and reliability of this method is verified through the algorithm case.

  Results  The results show that the increase of parameter ω and specific heat ratio of ambient gas can increase the specific heat ratio of the final mixture, the peak values of shock wave and make the initial arrival time of shock wave to the cabin wall ahead of schedule. The increase of parameter ω can accelerate the expansion rate of detonation products at the initial stage of explosion and increase the peak of quasi-static pressure. While, the increase of specific heat ratio of ambient gas slows down the expansion rate of detonation products at the initial stage of explosion and has little effect on the final quasi-static pressure peak.

  Conclusions  It is concluded that the proposed equivalent EOS is of some reliability and the study result in this paper can provide certain reference and basis for the design of anti-explosion structure and damage assessment.