Command manual

Command list

MAT_POWDER_BURN

Material properties
Attention: This command is in the beta stage and the format may change over time.
*MAT_POWDER_BURN
"Optional title"
mid, $\rho$
$C_v$, $\gamma$, $e_0$, $v$, fid, $T_i$, $p_i$

Parameter definition

VariableDescription
mid Unique material identification number
$\rho$ Density
$C_v$ Heat capacity
$\gamma$ Heat capacity ratio $(C_p/C_v)$
$e_0$ Combustion energy per unit mass
$v$ Initial co-volume (dimensionless)
fid Burn rate function ID
$T_i$ Ignition temperature
$p_i$ Ignition pressure

Description

This material command is used to model unburned propellant as rigid grains and its combustion products as discrete particles.

The command needs to be combined with POWDER_BURN_IGNITE and PARTICLE_DOMAIN. POWDER_BURN_IGNITE is used to describe the ignition location and PARTICLE_DOMAIN defines gas-structure contacts and limits the region in space where the combustion products (discrete particles) are modeled. The number of discrete particles that are used to model the combustion products are specified in the PART command (parameter $N_{perode}$).

Example

Internal ballistics (burning propellant)

Propellant grains burning in a simple internal ballistics demonstration model.


*UNIT_SYSTEM
SI
*PARAMETER
rho = 2200.0, "powder density"
Cv = 700.0, "heat capacity"
gamma = 1.4, "Cp/Cv ratio"
e0 = 1.2e6, "combustion energy per unit mass"
cvol = 0.3, "initial co-volume"
a = 1.0e-5, "burn rate parameter 1"
n = 0.6, "burn rate parameter 2"
c = 0.0001, "burn rate parameter 3"
patm = 1.0e5, "burn rate parameter 4"
Ti = 500.0, "ignition temperature"
pi = 1.0e6, "ignition pressure"
xi = 0.0, "ignition point X"
yi = 0.0, "ignition point Y"
zi = 0.0, "ignition point Z"
ti = 0.0, "ignition time"
Ri = 0.02, "ignition radius"
Np = 800000, "total number of particles"
#
# --- Propellant material properties ---
#
*MAT_POWDER_BURN
2, [%rho]
[%Cv], [%gamma], [%e0], [%cvol], 123, [%Ti], [%pi]
*FUNCTION
"burn rate"
123
%a*max(%patm,p)^%n + %c
#
# --- Ignition location ---
#
*POWDER_BURN_IGNITE
"ignition location"
1
[%xi], [%yi], [%zi], [%ti], [%Ri]
#
# --- Define number of particles in PART command ---
#
*PART
"propellant"
2, 2, 0, 0, 0, 3.0e-8, 0, 0, [%Np]
#
# --- Define region in space where the discrete particles are active ---
#
*PARTICLE_DOMAIN
ALL, 0, 0
-0.06, -0.06, -0.01, 0.06, 0.06, 1.0
*END