There is a simplest explaination of fluid mechanics

1. HGL & EGL
By: Dr. Ezzat Elsayed G. SALEH
Civil Eng. Dept.
‫يا‬‫ن‬‫مل‬‫ا‬ ‫جامعة‬
‫ندسة‬‫له‬‫ا‬ ‫ية‬‫لك‬
CVE 215

3. The development of hydraulic theory has produced three
important basic tools (equations) which are fundamental to
solving most hydrodynamic problems:
 Discharge and Continuity,
 Energy, and
 Momentum.
They are not difficult to master and you will need to
understand them well.

4. Boundary
Effects

5. Z
Potential Head :
Pressure Head:
𝑷∕ (𝝆 𝒈)
Hydraulic Grade
Line (HGL)
+
Velocity Head: V2/ 2 g
+
Energy Grade
Line (EGL)
The Total Head at any Cross-section H = Z + (P/  g) + (V2/ 2g )

6.  Hydraulic Grade Lines and
Energy Lines provide a
scaled, visual
representation of energy in
a system (along the flow
path), which helps identify
points of concern in the
design and analysis of
hydraulic systems.
B
2
A
2
g
2
V
z
g
P
g
2
V
z
g
P
























7. HGL and EGL for a pipe of different levels.

8.  
HGL and EGL for a pipe of different levels.
Reference Datum
T.E.L.
(T.E.L.)1 (T.E.L.)2

9. HGL and EGL at a sharp-edged pipe entrance.

10. Change in HGL and EGL due to change in pipe diameter

11. Drop in HGL and EGL due to valve

12. Change in HGL and EGL due to Flow through a nozzle

13. Negative gage pressure when pipe above EGL

14. Rise in HGL and EGL due to pump

15. Drop in HGL and EGL due to turbine

16. Motor or Generator?
acting as a MOTOR
Motor or Generator?
acting as a GENERATOR
Pump-Turbine installation