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;
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;
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;
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;
Small Satellites 
Great information.