Question

In the case of dam spillways, the approaching Froude number usually lies in the range of __________

(a) less than 2.5 m

(b) 2.5 – 4.5

(c) 4.5 – 9.0

(d) more than 9.0

This question was addressed to me during a job interview.

Question is taken from Energy Dissipation Below Overflow Spillway topic in division Spillways, Energy Dissipators and Spillway Gates of Irrigation Engineering

Answer 1

Right choice is (c) 4.5 – 9.0

Easiest explanation: Froude number varying between 2.5 and 4.5 generally occurs in canal weirs, canal falls, diversion dams, etc. For dams and spillways, the Froude number is in between 4.5 and 9.0 i.e. steady jump and the jump is well balanced.