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Development of a Design Methodology Against Fast Cook-Off Threat for Insensitive Munitions

ŞAHİN, Hakan
NARİN, Bekir
Kurtuluş, Dilek Funda
This work provides a design methodology for a typical energetic system to get Type V insensitive munition (IM) response against fast cook-off threat. Experimental and numerical results for a generic test item filled with PBXN-109 explosive are presented. Two key aspects of IM design against fast cook-off threat are investigated, which are "time-to-reaction" and "critical ventilation area". By dividing the problem to pre-ignition and post-ignition, the complexity of the problem is reduced. The first part of the study covers two-dimensional and three-dimensional simulations of the problem, where the generic test item is modelled using commercial CFD software (ANSYS-Fluent). The second part of the study reveals low pressure (2-10 MPa) burning characteristics of a PBXN-109 by strand burner tests. After obtaining the pressure dependent burning rate, a conservation of mass equation is used to determine the chamber pressure using MATLAB Simulink software. Calculations are in reasonable agreement with the experimental results. Calculations are compared with the tests performed. The results are in reasonable agreement with some discrepancies of 8.9% for time to reaction prediction and of 10.9% for ventilation characteristics analyses. Possible reasons of these differences are discussed.