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Fluid Dynamic Characterization of Turbo-machinery
P M V Subbarao
Professor
Mechanical Engineering Department
Development of Measures for Solid FluidInteractions!!!
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MEL346 : Syllabus
Introduction: turbomachinery / history / types /classification.
Euler equation for turbomachines.
Thermodynamics and fluid mechanics of turbomachineryMass, momentum and energy.
Radial equilibrium theory and design of blades for aturbomachine.
Design of Hydraulic turbines.
Axial flow turbines and compressors: theory and design Centrifugal compressors & Pumps
Wind Turbines
Micro Turbines
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References
Fluid Mechanics, Thermodynamics of Turbomachinery :
S.L. Dixon.
Principles of Turbomachinery: R.K. TURTON.
Handbook of Turbomachineryedited by Earl Logan, Jr. &Ramendra Roy.
The Design of High-Efficiency Turbomachinery and Gas
TurbinesDavid G Wilson & T Korakianitis.
Principles of Turbomachinery in Air Breathing EnginesE A Baskharone.
Steam Turbines for Modern Fossil-Fuel Power Plants;
Alexander S Leyzerovich.
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Attendance Policy
Below 80% -- one grade less.
Below 70% -- Two grades less.
Below 60% -- F Grade.
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Fluid Dynamics of A Turbomachine
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The Ancient Design : Undershot Water Wheel : 4000BC
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Various Types of Modern Turbomachine
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SOME TYPES OF WIND TURBINES: HAWT
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SOME TYPES OF WIND TURBINES: VAWT
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Why so many different types of either pump (compressor)
or turbine are in use ?
Is it due to (almost) infinite range of service requirements?
As a fact, for a given set of operating/resourcerequirements ,
there should be only one type of pump or turbine which is
best suited to provide best/optimum performance.
Why So Many?
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Classification of Turbo-machines
Two main categories of turbo-machine are identified:
Firstly, those which absorbpower to increase the fluid
pressure or head (fans, compressors and pumps);
Secondly, those thatproducepower by expanding fluid to
a lower pressure or head (hydraulic, steam and gas
turbines).
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Classification : Flow Path
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Classification : Flow Path
Turbomachines are further categorised according to thenature of the flow path through the passages of the rotor.
When the path of the through-flow is wholly or mainlyparallel to the axis of rotation, the device is termed an axialflow turbomachine.
When the path of the through-flow is wholly or mainly in aplane perpendicular to the rotation axis, the device istermed a radial flow turbomachine.
Mixed flow turbomachines are widely used.
The term mixed flow refers to the direction of the through-flow at rotor outlet when both radial and axial velocitycomponents are present in significant amounts.
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SolidFluid Interaction Level
Open flow
No casing or enclosure for the rotating device
Propeller is an open flow power consuming
device.Windmill is an open flow power generating
device.
Enclosed or encased flow devices
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Further Classification of Turbomachines
Compressibility of the fluid
IncompressibleThe density is constant through the entire flow process;liquid pumps.
Compressible; Gas flows: compressors.
Impulse or reaction machines
Impulse: pressure changes are absent in the flow through the rotor. Inan impulse machine, all the pressure change take place in nozzles
Reaction: pressure changes in rotor are present.
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Leonhard Euler
Leonhard Euler (1707-1783) was
arguably the greatest mathematician of
the eighteenth century.
One of the most prolific writer of all
time; his publication list of 886 papers
and books fill about 90 volumes.
Remarkably, much of this output datesfrom the last two decades of his life,
when he was totally blind.
Euler's prolific output caused a
tremendous problem of backlog: the St.
Petersburg Academy continued
publishing his work posthumously for
more than 30 years.
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Theoretical and Rigorous Work of French
Bernoulli and Leonhard Euler.
1750:Euler offered a memoir containing analysis and
equations for hydraulic turbines.
1754: An idealized theoretical application of Newtons
Law to centrifugal impellers.
Known as Euler Equation.
Did much to help the development of hydraulic machinery. 1767: Relation between Torque and Change in moment of
momentum of the fluid as it passed through the machine.
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Applications of Eulers Equation
Euler equation applies to all kinds of turbomachines.
Wind turbines ---- Pumps --- Gas turbines.
Axial flow machines to Radial flow to Mixed flow.
Energy extraction machinesEnergy consuming
machines.
For a turbine the value of Equation is negative.
For pumps, fans, blowers and compressors it is positive.
h S i i f
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The Superiority of Vector Parameters
kVjViVVzr
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Eulers Work Equation
Torque exerted by flow on blade row = shaft output torque
= Rate of change of Angular momentum of fluid = t
Euler Theory:
kVjViVV zr
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Define, L as Angular momentum
Angular momentum is moment of linear momentum of
angular velocity, V
For a steady flow through a turbomachine:
Inlet rate of angular momentum :
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Exit rate of angular momentum at exit:
Change in Rate of angular momentum: