#### Thermodynamics I - Southern Polytechnic State University

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Transcript Thermodynamics I - Southern Polytechnic State University

One Minute Paper
Statics; reply
Fluid dynamics
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Fluids in motion
Pumps
Fans
Compressors
Turbines
Heat exchangers
Conservation
Energy & mass; neither created nor
destroyed in ordinary process
Control volume
Steady state: no accumulation nor
depletion
Flowing fluid
Steady flow
Uniform flow
Mass flow rate: Kg/ time, lbm/time
Volume flow rate: m3/time, ft3/time,
cfm, gpm
Continuity
Mass flow rate
Volume flow rate
Nozzle
(ρVA)1= (ρVA)2
Energy balance
Kinetic
Potential
Flow
Energy – changes in properties
Bernoulli Equation
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Energy per weight of flowing fluid
Head
Pressure
Velocity
Elevation
Bernoulli Equation
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Assumptions
Steady state
Incompressible fluid
No friction in fluid stream
Bernoulli Equation
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Useful because:
Process flow reasonable steady
Compressibility effects small
Friction effects minor
Example
Water flowing from hose attached to
a main at 400kPa. Boy covers most
of hose outlet with thumb, producing
a vertical, thin jet of high speed
water. What is maximum height of
jet?
Example
A large tank open to the atmosphere
is filled with water. A tap near the
bottom of the tank is opened to allow
flow from a smooth, rounded
opening. Find the outlet velocity.
Example
During a trip, motorist runs out of
fuel. A helpful driver allows you to
siphon fuel from her auto. (2) is
located 0.75m below (1); (3) is 2m
above (1). Siphon diameter is 4mm.
Find the minimum time to transfer 4
L of fuel & the pressure at (3). Fuel
density is 750 kg/m3.
Homework
Water flows through a 2-inch
diameter pipe at 200 lbm/min. Its
temperature is 60oF. Find the velocity
of water flow.
Homework
Water from a pipe line is diverted into
weigh tank for exactly 9 minutes.
Tank weight increases 4765 lbf.
Water temperature is 60oF.
Homework
Steady flow of gas through a pipe
whose diameter decreases from 1.0
meter to 60cm. The gas density
decreases from 2 kg/m3 to 1.6 kg/m3.
The entering velocity is 25 m/s.
What is exit velocity?
Test 1
Tuesday 1/31 & Wednesday 2/1 for
Sections 002 & 003 respectively
Statics: chapters 4 & 5
Formula sheets okay; texts for tables
& graphs
Early start
References
Images & examples
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Mechanics of Fluids, 3rd Edition, Potter & Wiggert,
Brooks & Cole
Applied Fluid Mechanics, 6th Edition, Mott, Prentice Hall
Engineering Fluid Mechanics, 5th Edition Crowe, &
Roberson, Wiley
Which of the examples
were helpful?
Why?