PROGRAM FOR OTTO CYCLE USING MATLAB

PROGRAM FOR OTTO CYCLE (AIR STANDARD) USING ENGINE KINEMATICS

• In this program we are going to plot P vs V diagram for otto cycle of an engine.
• Taking gamma =1.4
• Using parameters p1,p2,p3,p4 for pressure and v1,v2,v3,v4 for volume, and t1,t2,t3,t4 for temperature .
• here we are taking t3=2300K
• using the relation p*v^gamma=constant we will find above mentioned parameters on state point variables 1 ,2,3 apectively.nd 4 respectively.

• clear all
  close all
  clc
  
  %INPUTS
  gamma=1.4
  t3=2300
  
  %State variables
  p1=101325
  t1=500
  
  %Engine geometric parameters
  bore=0.1;
  stroke=0.1;
  con_rod=0.15;
  cr=12;
  
  
  %Calculating the swept volume and clearance volume
  v_swept=(pi/4)*bore^2*stroke;
  v_clearance=v_swept/(cr-1);
  
  v1=v_swept+v_clearance
  v2=v_clearance
  
  %State variables at state point 2
  %p2v2^gamma=p1v1^gamma
  %p2=p1*(v1/v2)^gamma=p1*cr^gamma
  p2=p1*cr^gamma;
  
  %p1v1/t1=p2v2/t2|t2=p2*v2*t1/(p1*v1)
  t2=p2*v2*t1/(p1*v1);
  constant_c=p1*v1^gamma;
  V_compression=otto_cycle_engine_kinematics(bore,stroke,con_rod,cr,180,0);
  P_compression=constant_c./V_compression.^gamma;
  
  
  %state variables at state point 3
  v3=v2
  %p3v3/t3=p2v2/t2|p3=p2*t3/t2
  p3=p2*t3/t2;
  constant_c=p3*v3^gamma;
  V_expansion=otto_cycle_engine_kinematics(bore,stroke,con_rod,cr,0,180);
  P_expansion=constant_c./V_expansion.^gamma;
  %state variables at state point 4
  v4=v1
  %p3v3^gamma=p4v4^gamma|p4=p3(v3/v4)^gamma
  p4=p3*(v3/v4)^gamma
  
  figure(1)
  hold on
  plot(v1,p1,\'*\',\'color\',\'r\')
  plot(V_compression,P_compression)
  plot(v2,p2,\'*\',\'color\',\'r\')
  plot(v3,p3,\'*\',\'color\',\'r\')
  line([v2 v3],[p2 p3],\'color\',\'b\')
  plot(V_expansion,P_expansion)
  plot(v4,p4,\'*\',\'color\',\'r\')
  line([v4 v1],[p4 p1],\'color\',\'b\')
  xlabel(\'volume\')
  ylabel(\'Pressure\')
  
  
  
  
  

• 
• computing engine kinematics by introducing \'\'function\'\' command.

• function [V]=otto_cycle_engine_kinematics(bore,stroke,con_rod,cr,start_crank,end_crank)
  
  
  a=stroke/2;
  R=con_rod/a;
  
  v_s=(pi/4)*bore^2*stroke;
  v_c=v_s/(cr-1);
  
  theta=linspace(start_crank,end_crank,100);
  
  term1=0.5*(cr-1);
  term2=R+1-cosd(theta);
  term3=(R^2-sind(theta).^2).^0.5;
  
  V=(1+term1*(term2-term3)).*v_c;
  end
  
  
  
  

• Thermal efficiency of the otto cycle .
•