Question

The head loss through a siphon barrel is usually given by Unwin’s formula by neglecting velocity of approach as HL = [1 + F1 + F2. L/R] V^2/2g, where F1 and F2 respectively represent the coefficient of head losses due to?

(a) Barrel friction and entry

(b) Entry and barrel friction

(c) Barrel friction and exit

(d) Exit and barrel friction

I got this question by my college professor while I was bunking the class.

My question comes from Cross Drainage Work Design topic in division Cross Drainage Work of Irrigation Engineering

Answer 1

Correct answer is (b) Entry and barrel friction

Best explanation: The head loss through siphon barrels by Unwin’s formula is given as:

HL = [1 + F1 + F2. L/R] V^2/2g

where F1 is coefficient of head loss at entry and F2 is coefficient such that loss of head due to surface friction is given by F2 = a[1+b/R], a and b are the values depending upon the material of the surface of the barrel.