Fluid Mechanics 07

Hydraulic and Energy Grade LinesEGL:- Energy Grade line indicate the total head at any point in the system.

HGL:- Hydraulic Grade Line indicate the piezometric head at any point in the system

Hydraulic and Energy Grade Lines

Pump Add head to the System

Turbine

Nozzle

Nozzle increase the velocity and if discharge to atmospheric the term of pressure head will be zero

Change in pipe diameter

Negative Pressure

ExampleA pump draws water (50°F) from a reservoir, where the water-surface elevation is 520 ft, and forces the water through a pipe 5000 ft long and 1 ft in diameter. This pipe then discharges the water into a reservoir with water-surface elevation of 620 ft. The flow rate is 7.85 cfs, and the head loss in the pipe is given by

Determine the head supplied by the pump, hp, and the power supplied to the flow, and draw the HGL and EGL for the system. Assume that the pipe is horizontal and is 510 ft in elevation.

Solution WhereP1=P2=Patm=zeroV1=v2=zeroHt=zero, z1=520 ft, z2=620 ft

hL= 0)==77.6 ft

=178 ft