Unexploded ordnance (UXO) usually uses a metal/explosive composite structure, filled with energetic materials in the metal shell. Nowadays, 2,4,6-trinitrotoluene (TNT) has become one of the most common charges found in UXO, because of its high reaction energy, low friction and impact sensitivity, and mature production process, low manufacturing cost. For UXO loaded with TNT and other military explosives, the main methods of elimination are manual failure, explosive induction, shaped charge perforation, high heat agent melting and so on. The common feature of these methods is that they all need to operate at a close distance or even touch the UXO. Due to the instability of UXO, these methods have certain security risks. In recent years, with the continuous progress of laser technology, especially high-power laser technology, the use of laser irradiation ablation to destroy UXO has become possible and gradually developed. Based on directed energy technology, the new laser removal method has the characteristics of fast, safe, low indirect damage, low cost, no noise and hidden operation, and can remove UXO at a safe distance, which is very in line with the security concerns, so the method has received considerable attention.

Aiming at the problem that high energy laser irradiation of unexploded ordnance is easy to produce explosion, which will cause great harm to the surrounding environment, the pressure relief hole diameter required for stable combustion of explosive under the condition of shell damage is studied, and the law between different charge diameters and the required safety pressure relief hole diameter is found.

Based on the explosive exponential combustion law and the gas product flow choked theoretical model, the pressure development model of the shell charge under limited pressure relief was established. A simplified calculation method for the combustion area of the cylindrical charge was proposed, and a calculation program was developed based on MATLAB software.

Based on the simulation program written in MATLAB software, the pressure relief hole diameter required for stable combustion of UXO internal explosive with 120, 140, 160, 180, 200, 400 and 800 millimeter charge diameter is calculated, which are 20, 24, 28, 32, 36, 40, 80 and 160 millimeter respectively. The linear relationship between the diameter of the charge and the diameter of the safety relief hole is obtained.

Aiming at the problem that unexploded ordnance is prone to explosion when destroyed by non-contact methods such as laser irradiation, which has a great impact on the surrounding environment, this paper takes the cylindrical shell charge with the aspect ratio greater than 1 as the model background, combined with the flow congestion model, exponential combustion law and zero-dimensional internal ballistic theory, and establishes the pressure development model of explosive burning under the condition of limited pressure relief. The pressure development law of explosive burning in shell under different pressure relief conditions is calculated under the preset safety pressure of 90 MPa. It is concluded that the diameter of the safety relief hole set on the side of the cylindrical shell charge is almost linear with the diameter of the charge, and the diameter of the relief hole set according to 0.2 times the diameter of the cylindrical charge can safely relieve pressure. The research results of this paper have a theoretical guiding role in ensuring the destruction of unexploded ordnance in the combustion state.