Complex Flow Field Characteristics inside Combustion Chamber During the Secondary Ignition Process of CTA

doi:10.12382/bgxb.2023.0499

Abstract

Abstract:

The flow field characteristics inside the combustion chamber during the secondary ignition process of a large caliber cased telescoped ammunition (CTA) is studied. A two-dimensional axisymmetric two-phase reacting flow model based on the Euler-Euler approach is used, combined with dynamic grid division theory and user-defined function technology, to numerically simulate the secondary ignition internal ballistic process of a 105mm CTA armor-piercing projectile. The results show that the main charge bed is ignited after the rupture of combustible guide tube, and the gas converges in the bottom area of the projectile, forming local eddies. The intensity of the eddies gradually increases, and the temperature at the center of the eddies gradually increases. Under the action of gas phase force, the main charge bed is compressed axially and radially to the bottom area of the projectile, and then is dispersed by a large amount of gas into the entire combustion chamber. It is found that the maximum breech pressure during the secondary ignition process is 560MPa, and the muzzle velocity reaches 1650m/s.

Key words: cased telescoped ammunition, two-phase reacting flow, internal ballistics, flow field characteristic, numerical simulation

CLC Number:

TJ301

GUO Junting, YU Yonggang. Complex Flow Field Characteristics inside Combustion Chamber During the Secondary Ignition Process of CTA[J]. Acta Armamentarii, 2024, 45(7): 2282-2293.

Figures/Tables 20

Fig.1 Schematic diagram of CTA structure

Fig.2 Schematic diagram of seven-perforation propellant

Fig.3 Calculation domain of secondary ignition process for CTA

Fig.4 Axial distribution curve of combustion chamber pressure (1.4ms)

Fig.5 Comparison of simulated breech pressure-time curve with experimental results

Table 1 Calculation parameters for the first ignition process

参数	数值	参数	数值
ω_b/kg	0.007	ρ_p/(kg·m^-3)	1600
f_b/(kJ·kg^-1)	950	m/kg	6
p_0b/MPa	10	l_gb/m	0.15

Fig.6 Curves of internal ballistic parameters over time during the first ignition process

Fig.7 Schematic diagram of the initial moment of the secondary ignition process

Table 2 Calculation parameters for the secondary ignition process

参数	数值	参数	数值
ω_m/kg	5.9	α	0.001
l_gm/m	5	c_p/(J·kg^-1·K^-1)	1825
ρ_p/(kg·m^-3)	1600	λ_g/(W·m^-1·K^-1)	24.38
f_m/(kJ·kg^-1)	1225	p_0m/MPa	30
φ₁	1.12	k	1.25

Fig.8 Distribution and streamline distribution of pressure in the combustion chamber during the secondary ignition process

Fig.9 Velocity vector diagram of gas phase in the combustion chamber during the secondary ignition process

Fig.10 Axial velocity distribution of gas along the axis at different times

Fig.11 Radial velocity distribution of gas phase along the annular surface (r=54.5mm) at different times

Fig.12 Distribution of void fraction in the combustion chamber during the secondary ignition process

Fig.13 Distribution of gas phase temperature in the combustion chamber during the secondary ignition process

Fig.14 Pressure distribution along the axis at different times

Fig.15 Curves of pressure over time at different monitoring points

Fig.16 Curves of breech pressure and bottom pressure over with time

Fig.17 Curve of projectile velocity over time

Fig.18 Projectile velocity-displacement curve

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