Turbo machine

1. P.E.S. College of Engineering, (An Autonomous Institution
affiliated to Visvesvaraya Technological University, Belagavi),
Aided by Govt. of Karnataka Mandya-571401
Srikanthshekar K C
Assistant Professor
Department of Mechanical
TURBO MACHINES
P18ME54

2. • Fluid mechanics is the branch of physics concerned with the mechanics of fluids.
It can be divided into
• Fluid statics, the study of fluids at rest; and
• Fluid dynamics, the study of the effect of forces on fluid motion.
General classification of fluid mechanics
• Turbo machines ; Turbine
• Reciprocating Machines; Pump
• Various fluid lifting devices ; Hydraulic ram
• Pumps transmitting fluids ; Gear pump

3. Functional classification of fluid mechanics
• According to energy consideration
• According to increase or decrease in pressure
• According to increase or decrease in pressure
• According to direction of flow
• According to the direction of movement of machines
• According to the principle on which they are designed

4. Turbo Machine
Any device that extracts energy from or imparts energy to a continuously moving stream of fluid
can be called a turbomachine.
A turbo machine is a device in which energy transfer occurs between a flowing fluid and rotating
element due to dynamic action. This results in change of pressure and momentum of the fluid.
Energy conversion
Turbomachines can be categorized on the basis of the direction of energy conversion:
•Absorb power to increase the fluid pressure or head (Compressors and pumps).
•Produce power by expanding fluid to a lower pressure or head (hydraulic, steam and gas
turbines).

5. Parts of turbo machines
• The following are the principal components of turbo machine:
• (i) Rotor
• (ii) Stator
• (iii) Shaft
• (iv)Housing
1. Rotating element (vane, impeller or blades)– operating in a stream of fluid. Rotor is a rotating element
carrying the rotor blades or vanes. Rotor is also known by the names runner, impellers etc. depending
upon the particular machine.
2. Stationary elements – which usually guide the fluid in proper direction for efficient energy conversion
process.
3. Shaft – This either gives input power or takes output power from fluid under dynamic conditions and
runs at required speed.
4. Housing – to keep various rotating, stationery and other passages safely under dynamic conditions of the
flowing fluid. E.g. Steam turbine parts and Pelton turbine parts.

7. Difference Between Turbomachine And
Positive Displacement Machine
Turbomachine Positive Displacement Machine
It creates Thermodynamic & Dynamic action b/w
rotating element & flowing fluid, energy transfer
takes place if pressure and momentum changes
It creates Thermodynamic &Mechanical action b/w
moving member static fluid, energy transfer takes
place with displacement of fluid
It involves a steady flow of fluid & purely rotating
motion of mechanical element
It involves a unsteady flow of fluid & reciprocating
motion
They operate at high rotational speed They operate at low speed
Change of phase during fluid flow causes
serious problems in turbomachine
Change of phase during fluid flow causes less
problems in Positive displacement machine
Efficiency is usually less Efficiency is higher
It is simple in design It is complex in design
Due to rotary motion vibration problems are less Due to reciprocating motion vibration problems are
more
E.g. Hydraulic turbines, Gas turbines, Steam turbines
etc.
E.g. I.C engines, Reciprocating air compressor, pumps
etc.

8. Energy exchange in Turbomachine
• Euler’s turbine equation: The Euler pump and turbine equations are
the most fundamental equations in the field of turbomachinery. These
equations can be derived from the moment of momentum equation
when applied for a pump or a turbine.

10. Newton’s third law
• Second law defines a force to be equal to the change in momentum
with a change in time. Momentum is defined to be the mass m of an
object times its velocity V.
• Third law states that for every action (force) in nature there is an
equal and opposite reaction.

11. ROTOR

19. Components of energy transfer
• 1. Components of energy transfer 1. (𝑽1
2−𝑽2
2)/𝟐g is change in absolute
kinetic energy during its passage through the machine in m2 /s2 or Nm/kg
• 2. (𝑼1
2−𝑼2
2)/𝟐g is change in centrifugal energy of fluid felt as static
pressure change in rotor blades in m2 /s2 or Nm/kg
• 3. (𝑽r2
2−Vr1
2)/2g is change in relative velocity energy felt as static pressure
change in rotor blades in m 2 /s2 or Nm/kg

20. Degree of reaction
• Degree of reaction or reaction ratio (R) is defined as the ratio of the
static pressure drop in the rotor to the static pressure drop in the stage
or as the ratio of static enthalpy drop in the rotor to the static enthalpy
drop in the stage.
Or
The ratio of energy transfer due to the change of static pressure in rotor
to total energy transfer in the rotor.