1

2

Presentation 3 !!A BSc Grade Lesson

Energy, hydraulic Grade line and applications of theseKaleem Arts

3

Group DetailsMembers:• Fazl e Ghafoor (38)• Kaleem Afzal Khan (39)• Zubair Ahmad (41)• Kausar Ali (42)• Zeeshan Khan (43)

4

Energy Grade LineA line that represents the elevation of energy head (in feet or meters) of water flowing in a pipe or channel.

The line is drawn above the hydraulic grade line (gradient) a distance equal to the velocity head (V2/2g) of the water flowing at each section or point along the pipe or channel.

5

Energy Grade Lineand can be expressed as:

EL = H = p / γ + v2 / 2 g + h = constant

along a streamline         whereEL= Energy Line (m)

and can be expressed as:

6

Energy Grade Line• For a fluid flow without any losses

due to friction (major losses) or components (minor losses) - the energy line would be at a constant level. In a practical world the energy line decreases along the flow due to losses.

7

Energy Grade Line• A turbine in the flow reduces the

energy line and a pump or fan in the line increases the energy line.

8

Hydraulic Grade LineThe Hydraulic Grade Line is a line representing the total head available to the fluid - minus the velocity head and can be expressed as:

HGL = p / γ + h         whereHGL = Hydraulic Grade Line (m)

9

Hydraulic And Energy Grade Line

• The hydraulic grade line lies one velocity head below the the energy line.

10

EGL And HGLIn case the cross section is constant along the streamline and the flow steady, discharge remains constant and also so does velocity. Therefore, velocity head remains the same as well. In that case, HGL will always remain parallel to EGL.

11

Applications of EGL and HGL in civil engg• APPLICATION OF HYDRAULIC GRADE

LINE:-

• 1)The hydraulic grade line indicate the pressure along the pipe

• 2)The vertical distance from the pipe to the hydraulic grade line is the pressure head at that point

• 3)The slope of hydraulic grade line is the measure of the rate of head loss

12

Applications of Energy Grade line in civil engg

• 4)Change in elevation of the hydraulic grade line is due to change in velocity and diameter

• 5)At pipe outlet pressure head is zero so the pipe elevation and the hydraulic grade line coincide

13

Applications Cont:

• 6) The hydraulic grade line is a straight line only if the pipe is straight and of uniform diameter

• 7) Energy grade line shows the rate at which the energy decreases in a pipe.

14

Referenceshttp://www.engineeringtoolbox.com/energy-hydraulic-grade-line-d_613.html

15

---End of Presentation---

17

Questions ..?