How do I plot the variables outside of the for loop for all iterations?

I need to calculate different equations with 2 changing variables, the second variable depends on the first. I can plot inside the for loop, but I can't replicate the plot once it has been put outside of the for loop, it only plots the last iteration of the loop. Any advice?

clc;
close all;
clear all;


Patm = 18750;
Tatm = 216.7;
U = 250;
R = 287; 
gamma_air = 1.4;
T04 = 1500;
Qr = 45000000; 
B = 6; 

eta_d=0.97;
eta_c=0.85;
eta_b=1;
eta_t=0.9;
eta_n=0.98;
eta_f=0.85;
eta_fn=0.97;

gamma_d=1.4;
gamma_c=1.37;
gamma_b=1.35;
gamma_t=1.33;
gamma_n=1.36;
gamma_f=1.4;
gamma_fn=1.4;

cp_c=(gamma_c/(gamma_c-1))*R;
cp_b=(gamma_b/(gamma_b-1))*R;
cp_n=(gamma_n/(gamma_n-1))*R;
cp_f=(gamma_f/(gamma_f-1))*R;

for Prc=5:0.5:40
    Mach=U/sqrt(gamma_air*R*Tatm);
    T02=(Tatm*(1+((gamma_d-1)/2)*Mach^2));
    P02=(Patm*(1+eta_d*((T02/Tatm)-1))^(gamma_d/(gamma_d-1)));
    P03=P02*Prc;
    T03=(T02*(1+(1/eta_c)*(Prc^((gamma_c-1)/gamma_c)-1)));
    for Prf=1:0.0001:5
        P08=P02*Prf;
        T08=(T02*(1+(1/eta_f)*(Prf^((gamma_f-1)/gamma_f)-1)));
        T05=T04-(T03-T02)-(T08-T02)*B;
        P05=P03*(1-(1/eta_t)*(1-T05/T04))^(gamma_t/(gamma_t-1));
        P06=P05;
        
        f=(T04-T03)/(Qr/cp_c-T04);
            
        Ue=sqrt(2*eta_n*(gamma_n/(gamma_n-1))*R*T05*(1-(Patm/P05)^((gamma_n-1)/gamma_n)));
        Uef=sqrt(2*eta_fn*(gamma_f/(gamma_f-1))*R*T08*(1-(Patm/P08)^((gamma_f-1)/gamma_f)));
            
        SpecificThrust=(1+f)*(Ue+B)*(Uef-(1+B))*U;
        TSFC=f/SpecificThrust;
        break

    end
end

figure(1)
hold on
plot(Prc,SpecificThrust,'-','LineWidth',2);
ylabel('Specific Thrsut (kN*s/kg)')
xlabel('Compressor Pressure Ratio')
grid on
title('Compression Ratio vs Specific Thrust')

[Image Analyst]

Then why not just put the plotting code inside the Prc loop right after the end of the Prf loop?

[Timothy Bjorgan]

I could, but I'm having another issue when it comes to plotting the Prf variable using the same concept. I'm looking to simplify the code and make multiple plots outside of the for loops to avoid future issues if possible. Apologies, I'm relatively new to Matlab.

Answer 1

[David Hill]

clc;
close all;
clear;
Patm = 18750;
Tatm = 216.7;
U = 250;
R = 287; 
gamma_air = 1.4;
T04 = 1500;
Qr = 45000000; 
B = 6; 
eta_d=0.97;
eta_c=0.85;
eta_b=1;
eta_t=0.9;
eta_n=0.98;
eta_f=0.85;
eta_fn=0.97;
gamma_d=1.4;
gamma_c=1.37;
gamma_b=1.35;
gamma_t=1.33;
gamma_n=1.36;
gamma_f=1.4;
gamma_fn=1.4;
cp_c=(gamma_c/(gamma_c-1))*R;
cp_b=(gamma_b/(gamma_b-1))*R;
cp_n=(gamma_n/(gamma_n-1))*R;
cp_f=(gamma_f/(gamma_f-1))*R;
Mach=U/sqrt(gamma_air*R*Tatm);
T02=(Tatm*(1+((gamma_d-1)/2)*Mach^2));
P02=(Patm*(1+eta_d*((T02/Tatm)-1))^(gamma_d/(gamma_d-1)));
Prc= linspace(5,40,10000);%need to match number of Prf (used 10,000)
P03=P02*Prc;
T03=(T02*(1+(1/eta_c)*(Prc.^((gamma_c-1)/gamma_c)-1)));
Prf = linspace(1,5,10000);%need to match number of Prc (used 10,000)
P08 = P02*Prf;
T08 = (T02*(1+(1/eta_f)*(Prf.^((gamma_f-1)/gamma_f)-1)));
T05=T04-(T03-T02)-(T08-T02)*B;
P05=P03.*(1-(1/eta_t)*(1-T05/T04)).^(gamma_t/(gamma_t-1));
P06=P05;
f=(T04-T03)/(Qr/cp_c-T04);
Ue=sqrt(2*eta_n*(gamma_n/(gamma_n-1))*R*T05.*(1-(Patm./P05).^((gamma_n-1)/gamma_n)));
Uef=sqrt(2*eta_fn*(gamma_f/(gamma_f-1))*R*T08.*(1-(Patm./P08).^((gamma_f-1)/gamma_f)));
SpecificThrust=(1+f).*(Ue+B).*(Uef-(1+B))*U;
TSFC=f./SpecificThrust;
figure(1)
hold on
plot(Prc,SpecificThrust,'-','LineWidth',2);
ylabel('Specific Thrsut (kN*s/kg)')
xlabel('Compressor Pressure Ratio')
grid on
title('Compression Ratio vs Specific Thrust')