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## ME 2204 Fluid Mechanics

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Title: ME 2204 Fluid Mechanics

1
ME 2204 Fluid Mechanics Machinery.
Dr.V.RAMJEEDean Rajalakshmi engineering
college
• Notes on lesson-

2
UNIT-1
• Introduction-
• Basic conceptsproperties of fluids-
• Fluid- solid- density- sp.wt- sp.gr-.temp
• Viscosity- vapour pressure-surface
tension-compressibility-pressure measurements-
control volume-flow characteristics-
• Continuity equation- energy equation-
• Momentum equation-

3
UNIT-2
• Flow through conduits-circular annuli-
• Boundary layer-concepts-
• Darcy-weisbach equation-
• Friction factor-Moody diagram-
• Minor losses-
• Pipes in series-
• Pipes in parallel-

4
UNIT-3
• Dimensional analysis-
• Buckinghams theorem-
• Dimensionless parameters-
• Models and similitude-
• Application of dimensionless parameters-

5
UNIT-4
• Rotodynamic machines-Theory-
• Velocity diagram- energy transfer-
• turbines-pumps-
• Work done specific speed-
• Efficiencies- centrifugal pumps-
• Performance curves- for pumps turbines-

6
Unit- 5
• Positive displacement machines-
• Reciprocating pumps-air vessels-
• Rotary pumps-
• Velocity triangle- specific speed-
• Efficiency- -
• Performance curves-

7
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8
CLOSED CIRCUIT WIND TUNNEL
9
CLOSED CIRCUIT OVER VIEW
10
Flow visualisation tank-
11
DRAG OF BODIES
• Smooth corners- less drag-streamlining

Cd2.2
Cd0.6
Cd1.6
Cd0.4
Cd1.0
12
Flow past a cylinder-
13
DRAG COEFFICIENT
14
Vortex shedding
Cross-flow oscillating force
V
Characteristic frequency
fS frequency (Hz) S Strouhal number 0.1850.2
(depending on Re) v flow velocity (m/s) d
cylinder dimeter (m)
15
Potential Flow
U(q) 2U? sinq
P(q) 1/2 r U(q)2 P? 1/2 r U?2
Cp P(q) - P ?/1/2 r U?2 1 - 4sin2q
16
STROUHAL NUMBER
17
TIME EFFECT
18
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19
vortex-inducedvibration of cylinders
20
Typical structures interested on VIV
21
Wind flow on/around buildings
22
ALONG ACROSS
Von Karman vortex street
gt 100 m tall Buildings (Holmes)
23
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24
View of the CT model inside the tunnel
25
HELICAL STRAKE
26
A GROUP OF CHIMNEYS
27
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28
AERODYNAMIC EXCITATIONS
• PRIMARY SOURCES
• Incoming turbulence, FT
• Vortex shedding, FW
• Motion-induced forces, FM
• F(t) Fturb(t) Fwake(t) FM
• Equation of motion
• MX CX KX FG

29
Wind Effects on Bridges
30
Length 850 m 2 side span each 335 m
width 12 m Bridge deck plate girder type
07.11.40 Bridge failed (4 months after
construction)Designed to with stand 45m/s
Failed at 19m/sFrequency of vibration changed
from 37 to 14 cycles/minOscillation half an
hour13.7 m sag183 m span broke
Computation of natural frequencies-Necessary
Before failure after failure
reconstructed
31
Aerodynamic Coefficients
Aerodynamic Forces and Moments
32
surface
• Solidity is the ratio of total rotor planform
area to total swept area
• Low solidity (0.10) high speed, low torque
• High solidity (gt0.80) low speed, high torque

R
a
A
Solidity 3a/A
Slide Courtesy NREL USA
33
Airfoil Nomenclaturewind turbines use the same
aerodynamic principals as aircraft
OR
Or
a
V
V
VR Relative Wind
a angle of attack angle between the chord
line and the direction of the relative wind, VR
. VR wind speed seen by the airfoil vector
sum of V (free stream wind) and OR (tip speed).
Slide Courtesy NREL USA
34
Wind sensitive structures
35
How Wind Effects are quantified?
• WIND TUNNELS 90
• FULL SCALE FIELD EXPERIMENTS 9
• COMPUTATIONAL WIND ENGINEERING
• ( Complex flow
visualisation )

36
Venturimeter-
37
a200 , Re 4104
38
Variation of wind velocity with time and height
39
Wind speed terrain topography
40
Design classification
41
Features of wind speed
• Increase in mean wind speed with height
• Turbulence intensity
• Wide range of frequencies in the fluctuations

42
Wind Effects on Buildings
43
• MODE SHAPES AMPLITUDE
• Stretched strings attached on both ends are
actually simpler
• Notice that each end remains fixed in place
• You are looking at different modes of oscillation
• The relative frequencies are in the ratio 1234

44
Drag of cars-
• Trucks- buses- trains-
• Aerodynamic drag-
• Different shapes of cars-
• Trailer- trucks-

45
Rotating cylinder-
• Applications-
• 1. Flettner rotors. Sailing ships-1924-
• 2. Drag reduction of trucks-
• 3. Magnus effect- balls- spin- cricket- tennis-
• 4. Wings to increase lift- less separation-

46
TURBINES AND PUMPS
• 1. PELTON TURBINE
• 2. FRANCIS TURBINE
• 3. KAPLAN TURBINE
• 4. PUMPS-reciprocating and centrifugal
pump-single stage and multi stage pumps-
• ( Gear pump- )

47
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48
Specific speed of turbines-
49
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50
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51
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52
Gear pump-
53
Velocity triangle-Turbine
54
Velocity Triangle-Pump
55
CONCLUSIONS
• BUILDING AERO DYNAMICS
• CHIMNEYS,TOWERS,TALL BUILDINGS.
• BRIDGES- buffeting- flutter-
• TRANSMISSION LINES.
• CABLES(MARINE).
• Drag of vehicles- POLLUTION CONTROL.
• Wind mills- power generation- turbines-
• Pumps- (reciprocating centrifugal pump)
• Airplanes- helicopter- hovercraft-

56
REFERENCE
• Dr.V.Ramjee Fluid Mechanics Machinery
.Eswar press 2005
• Kumar.k.l.engineering fluid mechanics. 1995.
• Hoerner.S.F.(1965) Fluid dynamic drag.
• B.Barlow,H.Rae and A.Pope(1999) Low speed wind
tunnel testing.
• Streeter- Bansal- som biswas- white-

57
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58
Pelton wheel bucket-
59
Gear wheel-pump-