Question

Define the minor head loss due to gradual contraction or enlargement.

Answer 1

LOSSES DUE TO GRADUAL EXPANSION AND CONTRACTION

Losses due to gradual expansion and contraction is very much less compared to sudden changes.

As contraction and expansion is very much sudden more energy will be desipated.

Loss due to gradual expansion :

Loss coefficient due to gradual expansion depends on pressure recovery coefficient,ratio of diameters and angle of enlargement.

"More the angle of enlargment more will be increase in loss"

BUT

Lower the angle more the length of pipe is required. as length of increases frictional loss increases.

Minimum loss consdiering both minor and frictional loss occur at optimum angle of 7 degrees.

loss due to gradual increase in pipe :

K = loss coefficent

V = Velocity in pipe

g = acceleration due to gravity

k value is taken from (ratio of diameter v/s angle of enlargment) table available in market.

Loss due to gradual contraction:

loss due to gradual increase in pipe :

K value depends on same like gradual one ratio of diameter and cone angle.

but K increases as angle gets decreases.

k value is taken from (ratio of diameter v/s angle of sudden contraction) table available in market.