import math
#Given:
n = 6. #Number of cylinders
V_d = 700. #Displaced volume per cylinder in cm**3
bp = 78. #Brake power in kW
N = 3200. #Angular speed of engine in rpm
m_f = 27. #Petrol consumption in kg/hr
CV = 44. #Calorific value in MJ/kg
#Solution:
#(1)
A_F = 12. #Air-fuel ratio
P1 = 0.9
T1 = 32+273 #Intake air pressure and temperature in bar and K
m_a = A_F*m_f #Air consumption in kg/hr
R = 287. #Specific gas consmath.tant in J/kgK
rho_a = P1*10**5/(R*T1) #Density of air in kg/m**3
eta_vol = m_a/(60*rho_a*V_d*n*10**-6*N/2) #Volumetric efficiency
#(2)
eta_bt = bp*3600/(m_f*CV*1000) #Brake thermal efficiency
#(3)
T = bp*60/(2*math.pi*N) #Brake torque in kNm
#Results:
print " 1)The volumetric efficiency, eta_vol = %.2f percent"%(eta_vol*100)
print " 2)The brake thermal efficiency, eta_bt = %.2f percent"%(eta_bt*100)
print " 3)The brake torque, T = %.0f Nm"%(T*1000)