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Composite Rocket Propellant

In this example we are going to build a chemistry table for an AP-composite rocket propellant, and investigate the effects due to increasing metallization of the grain. CEAGUI application from the NASA Glenn Research center was used to calculate molecular weight, ratio of specific heats and combustion temperature for different mixture ratio of AP/HTPB/AL. CEAgui Download for Microsoft Windows available http://www.grc.nasa.gov/WWW/CEAWeb/ceaguiDownload-win.htm here. Those results used to calculate characteristic velocity C* (figure of thermo-chemical merit for a particular propellant) and Ideal Isp.

clc; clear all; close all;

Input

Combustor pressure – 3000 kPa,

Reactant temperature – 325 K

Ru = 8314;      % Universal Gas Constant
g0 = 9.81;      % [m/s^2] Gravitation Acceleration
load matlab2
Mr = p05(:,1);  % Mixure Ratio
Temp = [p05(:,2),p5(:,2),p10(:,2),p15(:,2),p25(:,2)];
MWv  = [p05(:,4),p5(:,4),p10(:,4),p15(:,4),p25(:,4)];

Combustion Temperature

figure(1);
hold on
cstring='rgbcmk';              % color string
for i = 1:5
    plot(Mr,Temp(:,i),[cstring(mod(i,7)+1),'-*']);
end

title('Combustion Temperature vs Mixture Ratio & Metallized Fuel Fraction ')
legend('Metallized Fuel Fraction Al/HTPB = 0.5%','5%','10%','15%','25%',...
    'Location','Southeast');
xlabel('Mixture Ratio  M_O_x_i_d_i_z_e_r/M_F_u_e_l');
ylabel('Combustion Temperature T[K]')
hold off;project_01

Ratio of Specific Heats,Combustor

Gamma = [p05(:,3),p5(:,3),p10(:,3),p15(:,3),p25(:,3)];
figure(2);
hold on
for i = 1:5
    plot(Mr,Gamma(:,i),[cstring(mod(i,7)+1),'-*']);
end

title('Ratio of Specific Heats,Combustor')
legend('Metallized Fuel Fraction Al/HTPB = 0.5%','5%','10%','15%','25%',...
    'Location','Northeast');
xlabel('Mixture Ratio  M_O_x_i_d_i_z_e_r/M_F_u_e_l');
ylabel('Gamma')
hold off;project_02

Characteristic Velocity

Cdv = (Gamma*Ru./MWv.*Temp).^0.5./(Gamma.*((2./(Gamma +1)).^...
    ((Gamma + 1)./(Gamma -1))).^0.5);

figure(3);
hold on
for i = 1:5
    plot(Mr,Cdv(:,i),[cstring(mod(i,7)+1),'-*']);
end
title('Characteristic Velocity')
legend('Metallized Fuel Fraction Al/HTPB = 0.5%','5%','10%','15%','25%',...
    'Location','Southeast');
xlabel('Mixture Ratio  M_O_x_i_d_i_z_e_r/M_F_u_e_l');
ylabel('C^*')
hold off;project_03

Ideal Isp, based on infinite nozzle

Ispv  = Cdv./g0.*Gamma.*(2./(Gamma - 1).*(2./(Gamma +1)).^...
    ((Gamma + 1)./(Gamma -1))).^0.5;
figure(4);
hold on
for i = 1:5
    plot(Mr,Ispv(:,i),[cstring(mod(i,7)+1),'-*']);
end

title('Ideal Isp, based on infinite nozzle')
legend('Metallized Fuel Fraction Al/HTPB = 0.5%','5%','10%','15%','25%',...
    'Location','Southeast');
xlabel('Mixture Ratio  M_O_x_i_d_i_z_e_r/M_F_u_e_l');
ylabel('Specific Impulse, Isp[s]')
hold off;project_04

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