Chapter 6, Problem 6.26P

Interpretation Introduction

Interpretation: The flow rate of water through the pipe is to be determined by using the energy balance equation.

Concept introduction: The Energy balance across the pipe is given by the Bernoulli’s equation in which the sum of Potential head, Kinetic head and Pressure head is constant. The Bernoulli equation across 2 points of any system is given by:-

  $\frac{{\text{P}}_{\text{1}}}{\text{ρg}}\text{+}\frac{{\text{v}}_{\text{1}}{}^{\text{2}}}{\text{2g}}{\text{+ Z}}_{\text{1}}\text{+}\text{H}\text{=}\frac{{\text{P}}_{\text{2}}}{\text{ρg}}\text{+}\frac{{\text{v}}_{\text{2}}{}^{\text{2}}}{\text{2g}}{\text{+ Z}}_{\text{2}}\text{+}{\text{h}}_{\text{L}}$   ...... (1)

The notations used in equation (1) are:-

P₁ and P₂ are pressure at inlet and outlet

v₁ and v₂ are velocity at inlet and outlet

Z₁ and Z₂ are the locations of the fluid.

  $\text{ρ}$ = Density of the fluid

h_L = Head loss in the section

H = Head developed

g = Acceleration due to gravity

The equation of continuity states that the flow rate at point A is equal to the flow rate at other point B.

The flow rate is given as,

  $\text{Q}\text{=}\text{Av}$   ...... (2)

A = Area of the pipe

v = Velocity of the pipe at a point