OTTO CYCLE SIMULATOR

#otto cycle simulator

import math

import matplotlib.pyplot as plt

def engine_kinematics(bore, stroke, con_rod, cr, start_crank, end_crank):
### ENGINE KINEMATICS ###

#geometric parameters

bore = 0.1
stroke = 0.1
con_rod = 0.15
cr = 12
a = stroke/2
R = con_rod/a

#volume parameters

v_s = (math.pi/4)*pow(bore,2)*stroke
v_c = v_s/(cr-1)

sc = math.radians(start_crank)
ec = math.radians(end_crank)

num_values = 50

dtheta = (ec-sc)/(num_values-1)

v = []

for i in range(0,num_values):
theta = sc + i*dtheta
term1 = 0.5*(cr-1)
term2 = R + 1 - math.cos(theta)
term3 = pow((pow(R,2) - pow(math.sin(theta),2)),0.5)

v.append((1 + term1*(term2-term3))*v_c)

return v

#inputs
p1 = 101325
t1 = 500
gamma = 1.4
t3 = 2300

#geometric parameters
bore = 0.1
stroke = 0.1
con_rod = 0.15
cr = 12

#volume calculation
v_s = (math.pi/4)*pow(bore,2)*stroke
v_c = v_s/(cr-1)
v1 = v_s + v_c

#state point 2
v2 = v_c

p2 = (p1*pow(v1,gamma))/pow(v2,gamma)

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

p_compression = []

v_compression = engine_kinematics(bore, stroke, con_rod, cr, 180, 0)

constant = p1*pow(v1,gamma)

for v in v_compression:
p_compression.append(constant/pow(v,gamma))

#statepoint 3
v3 = v2

p3 = rhs*t3/v3

p_expansion = []

v_expansion = engine_kinematics(bore, stroke, con_rod, cr, 0, 180)

constant = p3*pow(v3,gamma)

for v in v_expansion:
p_expansion.append(constant/pow(v,gamma))

#statepoint 4
v4 = v1

p4 = (p3*pow(v3,gamma))/pow(v4,gamma)

t4 = p4*v4/rhs

efficiency = 1-(1/cr**(gamma-1))
efficiency = efficiency * 100

print('thermal efficiency =', efficiency)

plt.figure()
plt.plot([v2,v3], [p2,p3])
plt.plot(v_compression, p_compression)
plt.plot(v_expansion, p_expansion)
plt.plot([v4,v1], [p4,p1])
plt.xlabel('volume')
plt.ylabel('pressure')
plt.show()

thermal efficiency = 62.98928275128466