Effects of module number and firing condition on charge thermal safety in gun chamber

Abstract

Thermal safety of modular charge which is fed into and retained in the chamber after gun fires consecutively is first investigated with cook-off method. A two-dimensional cook-off model of modular charge in gun chamber is established and the cook-off process of modular charge in gun chamber is numerically simulated. Then the effects of module number and firing condition on charge thermal safety are evaluated by researching the cook-off response characteristics of modules. The results show that, under conditions of different module numbers the cook-off responses all occur on the module closest to the boundary of missile, and the single-base propellants located at the inner surface of cartridge ignite first. When the number of loaded module changes from 1 to 6, the cook-off response temperatures vary little, only in a small range of 478.1 K–482.4 K. The cook-off response times decrease logarithmically in the range of 211.2 s–166.7 s with the increasing length of residual air gap in gun chamber. The simulation results are well matched with the experimental data. Furthermore, different firing conditions have great influence on the cook-off response time, minor influence on the initial response position and little influence on the response temperature. Under the three conditions of consecutive 32 launches with 5 rounds/min, 43 launches with 1 round/min, and 41 launches with different firing frequencies, the cook-off response temperatures are 479.2 K, 481.1 K and 479.9 K respectively and the response times are 709.2 s, 211.2 s and 214.4 s respectively. The response position is near the middle area of the inner cartridge surface in the former condition and near the right area in the latter two conditions.