MEG217A – TURBO MACHINES

unit 1: BASICS OF TURBO MACHINES

Part_A: INTRODUCTION

By,
Prof. Ashish S. Utage
Mobile- 9028876791
Email- ashish.utage@mitwpu.edu.in
School of Mechanical Engineering,
MIT WPU, Pune
 Faculty Introduction
Prof. Ashish S. Utage
 B.E. Mechanical, M. E. Mechanical (Heat Power
Engg), Ph D Pursuing
 1 year Industrial experience
 9 years of teaching experience
 Area of Interest: Thermal Engg, Heat Transfer,
Refrigeration and Air Conditioning
 Seating Arrangement: Room No. B-003, Applied
Thermodynamics Lab, Mech Building
 Mobile No. : 9028876791
 Email ID: ashish.utage@mitwpu.edu.in
 UNIT – I: Introduction to Turbo Machinery &
Impact of Jet
Part A) Introduction
 Definition, Classifications, Fundamental
equations, Comparison with positive
displacement machines, Applications of turbo
machines.
Part B) Impact of Jet
 Law of Impulse momentum and its applications,
Force exerted on fixed and moving flat plate,
curved vanes, series of flat plates and radial
vanes, velocity triangles and their analysis,
work done and efficiency
 UNIT-I
Part A : Introduction to Turbo Machines

 Definition
A turbo machine is a device in which there is
continuous transfer of energy between a rotating
member and a flowing fluid, due to dynamic action
resulting in the change in the pressure and /or the
momentum of the fluid.
• The word Turbo implies that which spins or whirls
around.

 Example : Turbines, compressors, pumps, fans etc.

 What is a Turbomachine?
Turbo or turbinis is of Latin origin and
it implies that which spins or whirls around.
• A turbomachine is a rotarymachine

• Which always involves an energy transfer between a

continuously flowing fluid and a rotor

• It is a power or head generatingmachine

• It uses the dynamic action of the rotor or impeller or runner

which changes the energy level of the continuously flowing fluid
through the rotor.
 Features of turbo machines
1. There is basically a shaft mounted on bearings.
2. The “vaned rotor” is keyed onto the shaft.
3. “Rotor” is a general name :
• Rotor is known as runner in work-producing
turbo machines or turbines.
• Rotor is known as impeller in the work-
absorbing turbo machines, pumps or compressors.
4. Shaft is coupled to either a generator ( to produce
power) or a motor (to utilize power)
5. A stator encloses the rotor, it guides the flow of
fluid also it houses components such as guide vanes,
nozzles, or diffusers.
 Turbo Machines

Pelton Turbine

Radial Flow Turbomachine

Turbo Machines
 Turbo Machines

Twice as big as an Airbus A380 turbine, the steam-turbine rotor being

manufactured in Siemens’ Mülheim an der Ruhr factory is the biggest and
heaviest in the world
Fluid Dynamics of A Turbomachine
Classification of Turbo-machines
Turbomachines

Power producing Power absorbing

fluid with high fluid with

energy high energy

Rotor/runner work Impeller work

fluid with
fluid with
low energy
low energy

 Firstly, those that produce power by expanding fluid to a

lower pressure or head (Hydraulic and steam turbines)
 Secondly, those which absorb power to increase the fluid
pressure or head (fans, compressors and pumps);
 Classification of turbo machines.
1. Based on Energy transfer
a) Energy is given by fluid to the rotor - Power
generating turbo machine E.g. Turbines
b) Energy given by the rotor to the fluid – Power
absorbing turbo machine E.g. Pumps, blowers and
compressors.
2. Based on fluid flowing in turbo machine
a) Hydro turbo machines -Pumps
b) Thermal turbo machines-Compressors
E.g. Fluid - water, air, steam, hot gases, petrol etc.
Examples of turbomachines:

POWER GENERATING TURBOMACHINES

POWER ABSORBING TURBOMACHINES
 3. Direction of fluid flow in the machines
a) Axial flow – Axial pump, compressor or turbine
b) Mixed flow – Mixed flow pump, Francis turbine
c) Radial flow – Centrifugal pump or compressor
d) Tangential flow – Pelton water turbine.
4. Based on condition of fluid in turbo machine
a) Impulse type (constant pressure)
E.g. Pelton turbine
b) Reaction type (variable pressure)
E.g. Francis reaction turbines
5. Based on position of rotating shaft
a) Horizontal shaft – Steam turbines
b) Vertical shaft – Kaplan water turbines
c) Inclined shaft – Modern bulb micro
 Positive displacement machines
• In these machines the fluid is directed into a closed
volume.
• Energy transfer to the fluid is accomplished by
movement of the boundary of the closed volume
causing the volume to expand or contract .
• Example: Reciprocating compressor, screw pump,
gear pump etc.
• Heart is a good example of positive displacement
pump.
• Water meter is example of positive displacement
turbine.
Comparison between positive displacement
machine and turbo machines
Action
 Positive displacement machines creates
thermodynamic and mechanical action between a
near-static fluid and relatively slow moving
surface, causing change in volume or
displacement of the fluid.
 Turbo machines creates thermodynamic and
dynamic action between a flowing fluid and a
rotating element and involves energy transfer
with pressure and momentum changes.
Operation

 Positive displacement machines generally

involves a reciprocating motion and unsteady fluid
flow.
Example of positive displacement machines with
rotating motion are gear pump and screw pump.

 Turbo machines involves steady flow of fluid

and pure rotary motion of mechanical element.
 Mechanical features
 Positive displacement machines are low speed
machines and relatively complex in mechanical
design.
High weight per unit of power output.
Contains valves that are open part time.

 Turbo machines are high speed machine and

simple in design.
Light weight per unit of power output.
Valves are absent.
Efficiency of conversion process

 In positive displacement machines use of

positive containment and near static energy
transfer process results in high efficiency.

 In turbo machines due to dynamic action the

efficiency is low.
Volumetric efficiency
 Positive displacement machines have low
volumetric efficiency.
 Turbo machines have high volumetric
efficiency.

Fluid phase change and surging

 In Positive displacement machines fluid phase
change and surging have minor importance.
 In turbo machines fluid phase change and surging
can cause major difficulties in smooth operation
of machines
Sr. Positive displacement
Aspects Turbomachines
No. machines
1 Action Involves thermodynamic Involves thermodynamic and
and mechanical action dynamic action between a
between nearly static continuously flowing fluid and a
fluid and slow moving rotating element. The
surface, volume change pressure change occurs
causes pressure change primarily by means of
dynamic action of a rotating
element.
2 Operation Involves reciprocating Involves rotary motion with
motion, unsteady flow of nearly steady flow. Stopping
fluid, fixed amount of of the machine will let the
fluid being positively fluid state change rapidly and
contained during its become same as that of the
passage through the surroundings.
machine, stopping of the
machine during operation
traps a certain amount
of fluid whose state is
different from that of
the surroundings
Sr. Positive displacement
Aspects Turbomachines
No. machines
3 Mechanical Employs low speed, High speed machines, simple
features complex in mechanical in design, light weight, no
design, heavy per unit valves, vibration not severe,
output, valves are light foundation required.
present, vibration
problems, heavy
foundations required.
4 Efficiency Efficiency of energy Low.
of energy conversion during both
conversion expansion and
compression is high.
5 Volumetric Low High, Nearly 100%.
efficiency
6 Fluid phase Relatively minor Cavitation, surging cause
change and importance in these serious difficulties to
surging machines. smooth operation.
Applications of Turbomachines
Thank You.!!!
Any Questions ???