3. Its specific gravity (relative density) is equal to the ratio
of its density to that of water at standard temperature and pressure.
W
=
γ
γL
W
L
L
ρ
ρ
=S
Its specific gravity (relative density) is equal to the ratio
of its density to that of either air or hydrogen at some specified
temperature and pressure.
ah
G
γ
γ
=
ah
G
G
ρ
ρ
=S
where: At standard
condition
W = 1000 kg/m3
W = 9.81 KN/m3
4. Atmospheric pressure: The pressure exerted by the
atmosphere.
At sea level
condition:
Pa = 101.325 KPa
= .101325 Mpa
= 1.01325Bar
= 760 mm Hg
= 10.33 m H2O
= 1.133 kg/cm2
= 14.7 psi
= 29.921 in Hg
= 33.878 ft H2O
Absolute and Gage Pressure
Absolute Pressure: is the pressure measured referred to absolute zero
and using absolute zero as the base.
Gage Pressure: is the pressure measured referred to atmospheric
pressure, and using atmospheric pressure as the base
5. Atmospheric Pressure
Atmospheric pressure is normally about
100,000 Pa
Differences in atmospheric pressure
cause winds to blow
Low atmospheric pressure inside a
hurricane’s eye contributes to the
severe winds and the development of
the storm surge
6. x dx
v+dv
v
moving plate
Fixed plate
v
S dv/dx
S = (dv/dx)
S = (v/x)
= S/(v/x)
where:
- absolute or dynamic
viscosity
in Pa-sec
S - shearing stress in Pascal
v - velocity in m/sec
x -distance in meters
7. r h
Where:
- surface tension, N/m
- specific weight of liquid, N/m3
r – radius, m
h – capillary rise, m
C
0 0.0756
10 0.0742
20 0.0728
30 0.0712
40 0.0696
60 0.0662
80 0.0626
100 0.0589
Surface Tension of Water
r
cos2
h
γ
θσ
8. MANOMETERS
Manometer is an instrument used in measuring gage pressure in length of
some liquid
column.
Open Type Manometer : It has an atmospheric surface and is capable
in measuring
gage pressure.
Differential Type Manometer : It has no atmospheric surface and is
capable in
measuring differences of pressure.
Pressure Head:
where:
p - pressure in KPa
- specific weight of a fluid,
KN/m3
h - pressure head in meters of
fluid
h
P
γ
9. In steady flow the velocity of the fluid particles at any point is constant
as time passes.
Unsteady flow exists whenever the velocity of the fluid particles at a
point changes as time passes.
Turbulent flow is an extreme kind of unsteady flow in which the velocity
of the fluid particles at a point change erratically in both magnitude and
direction.
Types of flowing fluids:
10. More types of fluid flow
Fluid flow can be compressible or
incompressible.
Most liquids are nearly incompressible.
Fluid flow can be viscous or
nonviscous.
11. When the flow is steady, streamlines are often used to represent
the trajectories of the fluid particles.
13. 222111 vAvA
EQUATION OF CONTINUITY
The mass flow rate has the same value at every position along a
tube that has a single entry and a single exit for fluid flow.
SI Unit of Mass Flow Rate: kg/s
17. BERNOULLI’S EQUATION
In steady flow of a nonviscous,
incompressible fluid, the pressure, the
fluid speed, and the elevation at two
points are related by:
18. 1. Without Energy head added or given up by the fluid (No
work done by
the system or on the system:
L2
2
22
t1
2
11
H+Z+
2g
v
+
γ
P
=h+Z+
2g
v
+
γ
P
L2
2
22
1
2
11
H+Z+
2g
v
+
γ
P
=Z+
2g
v
+
γ
P
h+H+Z+
2g
v
+
γ
P
=+Z+
2g
v
+
γ
P
L2
2
22
1
2
11
2. With Energy head added to the Fluid: (Work done on the system
3. With Energy head added given up by the Fluid: (Work done by the
Where:
P – pressure, KPa - specific weight,
KN/m3
v – velocity in m/sec g – gravitational
acceleration
Z – elevation, meters m/sec2
+ if above datum H – head loss, meters
- if below datum
19. Ventury Meter
A. Without considering Head loss
flowltheoreticaQ
vAvAQ
Z
g2
vP
Z
g2
vP
2211
2
2
22
1
2
11
γγ
Manometer
1
2
B. Considering Head loss
flowactual'Q
vAvA'Q
HZ
g2
vP
Z
g2
vP
2211
L2
2
22
1
2
11
γγ
Meter Coefficient
Q
'Q
C
20. Orifice: An orifice is an any opening with a closed perimeter
Without considering Head Loss
1
2
a
a
Vena Contractah
By applying Bernoulli's Energy theorem:
2
2
22
1
2
11
Z
g2
vP
Z
g2
vP
But P1 = P2 = Pa and v1is negligible, then
21
2
2
ZZ
g2
v
and from figure: Z1 - Z2 = h,
therefore
h
g2
v
2
2
gh2v2
Let v2 = vt
gh2vt
where:
vt - theoretical velocity, m/sec
h - head producing the flow, meters
g - gravitational acceleration, m/sec2
26. Pump-Storage Hydroelectric power plant: During power generation the turbine-pump acts
as a turbine and
during off-peak period it acts as a pump, pumping water from the lower pool (tailrace)
back to the upper
pool (headrace).
Turbine-Pump
