Air standard Cycle using Python

PV Diagram visualizer.

Explanation:

Step1:

Entering the Title.

Step2:

Defining a function for input parameters(i.e. bore,stroke,con_rod,cr,start_crank,end_crank)

Step3:

Input geometric parametrics, volume computation, and state points and calculating the volumes and pressure ad different states.

Step4:

Plotting volume vs pressure.

Step5:

Calculating and printing thermal eficiency.

#engine kinematics
#otto ycle simulator


import math
import matplotlib.pyplot as plt

def engine_kinematics(bore,stroke,con_rod,cr,start_crank,end_crank):
	
	#geometric paramaeters
	a=stroke/2
	R=con_rod/a

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

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

	num_values=100
	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(R,2)-pow(math.sin(theta),2)
		term3=pow(term3,0.5)
		v.append((1+term1*(term2-term3))*v_c)
	return v	
	



#inputs
p1=101325
t1=500

#geometric parametrics
bore=0.1
stroke=0.1
con_rod=0.15
cr=12
gamma=1.4
t3=2300

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

#state point 2
v2=v_c

#p2v2^gamma=p1v1^gamma
p2=p1*pow(v1,gamma)/pow(v2,gamma)

#p2v2/t2=p1v1/t1
rhs=p1*v1/t1
t2=p2*v2/rhs

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

constant=p1*pow(v1,gamma)
for v in v_compression:
	p_compression.append(constant/pow(v,gamma))


#state point3
v3=v2

#p3v3/t3
rhs=p2*v2/t2
p3=rhs*t3/v3

v_expansion=engine_kinematics(bore,stroke,con_rod,cr,0,180)
p_expansion=[]
constant=p3*pow(v3,gamma)
for v in v_expansion:
	p_expansion.append(constant/pow(v,gamma))


#state point4 
v4=v1

#p4v46gamma

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

#p4v4/t4=rhs
t4=p4*v4/rhs

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.show()

#thermal eficiency
A= 1/pow((v1/v2),(gamma-1))
thermal_efficiency=(1-A)*100 

print("thermal_efficiency=",thermal_efficiency)

Results:

thermal_efficiency= 62.98928275128466