Below are my defined variables:
clear all
%% Step 1
% ========================================================================= %
% Basing on the motor and propellant data indicated in Table 1 and on the
% burning surface evolution shown in Figs. 5 and 6 and assuming a constant
% chambre temperature profile compute the following curves without taking
% into account the non-ideal parameters.
%% Step 1.1
%Find: The motor chamber pressure and the vaccume thrust as a
% function of both time and web assuming quasi-steady state (equilibrium)
% User inputs - First stage P80 SRM
% ========================================================================= %
mp = 88000; % Propellant Mass [kg]
ms = 7330; % Structural mass [kg]
l = 10.6; % length [m]
d = 3.0; % Diameter [m]
f = 3015; % Max thrust(vaccum) [kN]
bt = 110; % Buring time [sec]
isp = 280; % Specifi Impulse (vaccuum) [sec]
% User inputs - Propellant Ballistic Properties
% ========================================================================= %
a_0 = 1.847e-05; % Temperature coefficient @ 300 K [m/s * Pae-0.4]
temp_sens = 0.0015 % K^-1
n = 0.4; % Combustion index
tau = 0.0015; % Temperature sensitivity [k^-1]
rho_p = 1790; % Density [kg/m^3]
rho_c = 1; % Initial chamber density [kg
% User inputs - Propellant thermochemocal properties
% ========================================================================= %
T_F = 3550; % Flame temperature [K]
M = 29; % Molecular mass [kg/kmole]
gamma = 1.13; % Specific heat ratio
% User inputs - Motor geometrical properties
% ========================================================================= %
d_throat = 0.496; % Throat diameter [m]
e = 16; % expansion ratio
V_c = 8.6; % Initial chamber volume [m^3]
v_frac = 0.85; % volumetric loading fraction (V_c/(V_c+V_p)
% User inputs - Pressurizing Gas Properties
% ========================================================================= %
p_exit = 1.3e+05; % [Pa]
T_initial = 300; % [K]
T_1 = 285; %[ K ]
T_2 = 315; %[ K ]
% constants
% ========================================================================= %
R = 8314.5; % gas constant [J/kmol)
R_gas = 287; % J/kg K
% Calculations
% Find: The motor chamber pressure and the vaccum thrust as a
% ========================================================================= %
a_t = pi* (d_throat/2)^2; % Thrat area [m^2]
cap_gamma = sqrt (gamma * (2/(gamma + 1))^((gamma+1)/(gamma-1))); % capital gamma
c_star = (1/cap_gamma)*sqrt((R*T_F)/M);
