Centrifugal Pump Velocity diagram in Python

 from numpy import *

from matplotlib.pyplot import *

d1 = 0.2 # 200mm is 0.2m (inlet diameter)

d2 = 0.4 # 400 mm is 0.4m (outlet diameter)

n = 1200 #rotating speed in rpm

theta = 20 # degree

phi = 30 #degrere

u1 = pi*d1*n/60

u2 = pi*d2*n/60

fig = figure()

ax = fig.add_subplot(211)

vf1 = u1*tan(radians(theta))

vr1 = sqrt(vf1**2 +u1**2)

title('flow velocity')

# assumption relative velocit at inlet and outlet is same

a =([0,u1,u1,0])

b =([0,0,vf1,0])

ax.plot(a,b)

ax2 = fig.add_subplot(212)

title('flow velocity at outlet')

c = ([0,u2,vr1*cos(radians(phi)),0])

d = ([0,0,vr1*sin(radians(phi)),0])

axis('equal')

ax2 = fig.add_subplot(212)

vw2 = vf1/tan(radians(phi))+u1

title('flow velocity at outlet')

e =([0,u2,vr1*cos(radians(phi)),vr1*cos(radians(phi)),0])

f =([0,0,vr1*sin(radians(phi)),0,0])

ax2.plot(e,f)

axis('equal')

for better understanding how does this code work watch this video