REPUBLIC OF SERBIA

MINISTRY OF DEFENCE

www.mod.gov.rs

MINISTRY OF DEFENCE

Material Resources Sector

Defensive Technologies Department

Military Technical Institute

www.vti.mod.gov.rs

MODELING TWO-PHASE FLOW IN SMALL ARMS WITH NUMERICAL SOLUTION OF UNSTEADY HEAT TRANSFER THROUGH POWDER GRAIN

Ljubiša Tančić

Military Academy, Belgrade, ljtancic@gmail.com

Abstract: The interior ballistics problem of firing process in the small arms is considered. A mathematical model of a so called two-phase flow, which is created by gas - dynamic partial differential equations system, is used. Partial differential equations system has been solved numerical by finite difference method. Heat quantity which is crossing from powder gasses to powder grains, is determined, because this heat figures in flow energy equation. The equation of temperature distribution through deepness of powder grain is defined. As the example of numerical treatment of two-phase flow the numerical modeling of two-phase flow of powder grains and their combustion products in small arms barrel is shown. The employment conditions and shape of powder grains are variationed and their influence to the calculations results are numerical analyzed. Temperature distribution through deepness of powder grain is variationed and her influence to the calculations results are numerical analyzed. The whole procedure is included in a computer program, which results are verified through the comparasion with experimental results. The numerical results are analized and they compared with the experimental results and some conclusions for future work on this problem are given.

Key words: interior ballistics, firing process, distribution of temperature, powder grain.