PV Diagram Visualiser

First, we create the main program i.e otto.m

close all

clear all

clc

% Input Variables

bore_engine=0.1;

stroke_engine=0.1;

con_engine=0.15;

cratio_engine=12;

% Input

% gamma is ratio of specific heat used in efficiency formula

gamma=1.4;

t3=2300

%State Variables

p1=101325

t1=500

% Finding v1 and v2

v_s=(pi/4)*bore_engine^2*stroke_engine;

v_c=v_s/(cratio_engine-1);

v1=v_s+v_c

v2=v_c

% Main code, State Variable 2, p1*v1^gamma=p2*v2^gamma

% p1*v1/t1=p2*v2/t2

t2=p2*v2*t1/(p1*v1)

constant_e=p1*v1^gamma

V_compression=engine_kinematics2(bore_engine,stroke_engine,con_engine,cratio_engine,180,360)

% constant_e=P_compression*V_compression

P_compression=constant_e./V_compression.^gamma;

% State Variable 3

v3=v2

%p3*v3/t3=p2*v2/t2

% v3=v2

p3=p2*t3/t2

constant_e=p3*v3^gamma

V_expansion=engine_kinematics2(bore_engine,stroke_engine,con_engine,cratio_engine,0,180)

% constant_e=P_compression*V_compression

P_expansion=constant_e./V_expansion.^gamma;

% State Variable 4

v4=v1

p4=p3*(v3/v4)^gamma

% Thermal efficiency of engine is solely dependent on compression ratio and fixed value gamma.

thermaleff_e=1-1/(cratio_e^gamma-1);

figure(1)

hold on

plot(v1,p1,\'*\',\'color\',\'b\')

plot(V_compression,P_compression)

plot(v2,p2,\'*\',\'color\',\'b\')

plot(v3,p3,\'*\',\'color\',\'b\')

plot(V_expansion,P_expansion)

plot(v4,p4,\'*\',\'color\',\'b\')

% Joining Straight Lines

plot([v2 v3],[p2 p3])

plot([v4 v1],[p4 p1])

Now, we write for the function \'engine_kinematics2.m\' which has been called in the above program

function [v]=engine_kinematics2(bore_e,stroke_e,cond_e,cr_e,start_e,end_e)

a=stroke_e/2;

R=cond_e/a;

v_s=(pi/4)*bore_e^2*stroke_e;

v_c=v_s/(cr_e-1);

theta_e=linspace(start_e,end_e,100);

term1=0.5*(cr_e-1);

term2=R+1-cosd(theta_e);

term3=(R^2-sind(theta_e).^2).^0.5;

V=(1+term1*(term2-term3)).*v_c;

end