Transcript Thermodynamics I - Southern Polytechnic State University

Fluid Mechanics Principles &
Applications
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Educate.spsu.edu/faculty website
SPSU e-mail
“afm”
Syllabus
Notes - schedules
Power Point
AFM
 Outcomes
 Credits
 Text: Applied Fluid Mechanics, 6th
Edition, Robert Mott
AFM
 Impacts: chemical manufacture,
automobile systems, electrical
generation, petroleum refining, water
treatment
AFM
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Extensive impact on everyday life
Home hot water system
Potable water
Waste water
Natural gas
HVAC
Refrigeration
AFM
 Automobiles: fuel system, cooling
system, brakes, power steering
 Manufacturing: machine operations
 Farming: harvesting
 Construction: earth moving
 Mining
 Aircraft: control surfaces, landing
gear
AFM
 Mathematical approach → empirical
approach
 AFM: basics → working equation →
application
Practice
Text examples, class examples, homework, tests
AFM
 Learn A
 A basis for learning B
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Read text
Examples
Homework
Questions
One minute paper
AFM
 Learning Styles: Improves
understanding and retention.
• Active – work problems, apply in lab,
discuss in class, explain to someone.
• Visual – pictures, diagrams,
demonstrations.
• Sequential – build knowledge in logical
steps
AFM
 “You can take this course one of two
ways, seriously or again.” Dr.
Neathery – Oklahoma State Univ.
AFM
 Technicians: trained in set
procedures; focus on how, what,
when.
 Engineers: learned basics; know why.
Broader knowledge base.
AFM
 No cookbook
 Orderly/logical approach
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Read carefully
Describe system
Sketch
Assumptions
Principles & working equations; tables &
graphs
• Solve
• Reasonable
Approach
 “Most difficulties encountered are due
not to lack of knowledge, rather due
to lack of organization (of what you
know).” Dr. Cengel, N.C. State Univ.
AFM
 Assumptions – reasonable
Solve Equation
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Include units
Consistent unit system
Significant digits
Equation is a representation of an
actual physical process, not an
exercise in mathematics.
AFM
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Reasonable result
Make sense?
Sign
Units
Magnitude
AFM
 Presentations in real world: bosses &
customers: logical, neat, & orderly
 In AFM, to Instructor. Use same
standard
AFM
 Solid mechanics – objects stationary
(statics) or moving (dynamics)
 Fluid mechanics – fluids at rest or in
motion
• Gas – fills available volume; no
resistance to stress
• Liquid – limited volume; responds to
stress by continuous deformation.
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Gases – compressible
Liquids – ordinarily incompressible.
Hydrostatics
Hydrodynamics: closed pipe, open
channel, external flow
Unit Systems
 SI
 USCS
Properties
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Characteristics of system
Mass
Weight
Density
Specific weight
Specific gravity
Properties
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Specific volume
Ideal gas law
Compressibility: bulk modulus
Temperature
Engineering
Absolute
Viscosity
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Resistance to deformation
Proportionality constant
Absolute
Kinematic
Saybolt viscometer
Viscosity index
SAE viscosity
 SAE10W-40
• 10W for cold cranking engine
• 40 for engine operating temperature
Viscosity
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Temperature dependence
Liquid
Gas
Shear dependence - rheology
Pressure
 Intensity of a force
 System property
 Vs reference: gage, atmospheric,
absolute
 Pascal’s Paradox
 Manometer
• Barometer
• U-tube
Examples
 Mercury manometer is connected to
an air duct to measure its insice
pressure. The manometer deflection
is 15mm. Atmospheric pressure is
100kPa. Find the duct’s absolute
pressure. Hg  = 13,600kg/m3.
Examples
 Refer figure. Find the manometer
deflection.
Pascal’s Law
 An increase in pressure in an
enclosed system will be transmitted
throughout the entire system.
Hydraulic jack: Homework
 Exert 100N on jack handle; support
what force?
Homework
 Oil with a specific gravity 0f 0.8 forms
a layer 0.9m deep in an open tank
that is otherwise filled with water
having a depth of 2.10m. The water
temperature is 10oC.
 Calculate h
 Calculate P at the bottom of the tank
in gage pressure
Assignment
 Mott: Chapters 1 & 2
QUESTIONS
References
 Images & examples
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Fluid Mechanics Fundamentals & Applications, 6th Edition, Cengel & Cimbala, McGraw Hill
Applied Fluid Mechanics, 6th Edition, Mott, Prentice Hall
Engineering Fluid Mechanics, 5th Edition Crowe, Elger, & Roberson, Wiley
 Which of the problems were helpful?
 Why?