Ch.5-1 Introduction to Turbomachinery

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What is “Turbomachinery” ?

“turbo”

around.

or

“turbinis”

is Latin in origin and implies that which spins or whirls A turbomachine is a rotating (as opposed to reciprocating) device that extracts energy from or adds energy to fluids.

There are two main categories of turbomachines, i.e. • those • those

absorbs

power (e.g., pumps, fans, compressors), and

generates

power (e.g. hydraulic, steam, and gas turbines) A turbomachine changes the

enthalpy

the working fluids.

of One university. Many futures.

Review: Why “enthalpy”?

First Law of Thermodynamics for an open system (based on control volume analysis)     ( h 2  h 1 )  1 2 ( c 2 2  c 1 2 )  g ( z 2  z 1 )   Therefore,    ( h 1  h 2 ) What is enthalpy ?

h  u  pv u: internal energy pv: flow work Important: All these parameters (h, u, p, v) are properties of a substance.

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Example 1a (system): Steam Power Plant Siemens Steam Plants (SSP™) Reference: http://www.powergeneration.siemens.com/products-solutions-services/power-plant-soln/steam-turbine power-plants/

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Example 1b (system): Steam Turbine

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Example 2a: Tidal Stream Turbine

Tidal power is the only form of energy which derives directly from the relative motions of the Earth-Moon system. Tidal power is practically inexhaustible and classified as a renewable energy source. Tidal energy is periodical and predictable. In contrast, wind and solar energies cannot be well-predicted.

SeaGen

is the world's first large scale commercial tidal stream generator. It is four times more powerful than any other tidal stream generator in the world.

Reference: http://en.wikipedia.org/wiki/SeaGen One university. Many futures.

Example 2b: Tidal Stream Turbine

Click the following weblink: http://www.youtube.com/watch?v=qRUl1mJQHmc&list=PL994CD8692F04FA15&index=2 http://www.youtube.com/watch?v=tSBACzRE3Gw&feature=related One university. Many futures.

Example 3: Turbo Engines

Click the following weblink: http://www.youtube.com/watch?v=p1TqwAKwMuM&list=PL17E887C02E1576E6 http:// www.youtube.com/watch?v=Y0uQzLC851c&feature=PlayList&p=17E887C02E1576E6&index=3 http://www.youtube.com/watch?v=CXSi4GXUojo One university. Many futures.

Classification of Turbomachines According to the function:

•

Pumps/compressors

Absorbing power •

Turbines

Generating power

According to the flow direction:

•

Axial-flow turbomachine

Flow path parallel to axis of rotation •

Radial-flow turbomachine

Flow path perpendicular to axis of rotation •

Mixed-flow turbomachine

Both radial and axial flow components

According to the pressure change in a rotor:

•

Impulse (zero-reaction) turbomachine

Pressure changes across the nozzle/diffuser; Pressure does not change across the rotor (or blades).

•

Reaction (zero impulse) turbomachine

Pressure changes across both the nozzle/diffuser and the rotor.

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Example 4a: Centrifugal Compressor

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Jet engine

Example 4b: Centrifugal Turbines

Turbine and nozzles Shaft and turbine One university. Many futures.

Example 4c: Centrifugal Turbomachine

Nozzles and compressor blades One university. Many futures.

Example 5a: Axial Compressor

4-stage compressor A blade wheel (single stage) Jet engine One university. Many futures.

Example 5b: Axial Turbine

Axial gas turbine (rotor) Wind turbine Tidal turbine One university. Many futures.

Example 5c: Axial Compressor Stator

(To increase the pressure; to transfer kinetic energy to potential/pressure energy.) One university. Many futures.

Rotor

(To transfer mechanical energy to kinetic energy of gas; to partially increase the pressure.)

1 stage

= 1 stator blade wheel +1 rotor blade wheel

Example 6: Impulse Turbines

Simplest example

No pressure changes across the blades

Pelton hydraulic turbines One university. Many futures.