Introduction to fluid machines

Content:

Classification of fluid machines

Classification of turbomachines

Classification of fluid machines as to the

operation mode

Volumetric machines (or positive

displacement machines)

Turbomachines

Definition of volumetric machines

Machine that exchanges energy with the fluid via internal volume displacement

Alternative volumetric machine Rotating volumetric machine

NVpQ v

Q – Flow rate

v – Volumetric efficiency

p – Pressure increase

N – Motion frequency (Hz)

V – Displaced volume in each cycle

p

Q

N1 N2

Real

curves

Definition of volumetric machines

Machine that exchanges energy with the fluid via internal volume displacement

Turbomachine definition

Energy exchange

through blade torque

resulting from flow

deflection associated

with lift forces on the

rotating blades.

Flow machines classification with respect

to their function

Powered machines (pumps, fans and

compressors)

Powering machines (turbines)

Propellers (only turbomachines)

Flow machines classification as to the

flowing fluid

Hydraulic machines (incompressible fluids):

pumps, hydraulic turbines, fans, maritime

propellers.

Thermal machines (compressible fluids): gas

turbines, vapor turbines, compressors,

airplane propellers, wind turbines.

Turbomachines classification as to the

direction of the internal flow

Tangential turbomachines: the flow is

tangential to the rotor.

Axial turbomachines: flow without significant

radial component in the rotor.

Radial turbomachines: flow with significant

radial component at the rotor oulet (powered

t.) or rotor inlet (powering t.)

Mixed turbomachines: intermediate case

between axial and radial turbomachines.

Examples of tangential turbomachines

Two jets Pelton Turbine

Runner or rotor

Injectors

Pennstock

Examples of tangential turbomachines

Pelton Turbine of large

dimensions

• Vertical axel

• 6 jets (6 injectors)

Examples of tangential turbomachines

Spiral

casing

Guide

vannes

Rotor or

runner

Draft

tube

Examples of radial turbomachines

Radial reversible pump-

turbine: allows accumulation of

water in the upstream reservoir at

electrical off-peak consumption

period.

Examples of radial turbomachines

Radial pump

Radial pump with spiral casing and no guide vannes at rotor outlet

Rotor blades

Spiral casing

Pump exit

Medium pressure radial fan

1 stage radial pump with guide vanes at

rotor outlet

Pump exit Diffusor

guide

vanes

Rotor blades

Rotor

Pump

inlet

Casing

frontal

part

Spiral casing

Casing rear part

1 stage radial pump with spiral casing and diffusor guide vanes

Low pressure radial fan

Low pressure radial fan

Double flux 2 stages radial pump

9 stages radial pump

9 stages radial pump

Examples of

axial

turbomachines

Axial fan

Axial fan for tunnel ventilation. Rotor diameter 2.8 m.

Power 285 kW

Double flux low pressure rotor of an axial gas

turbine (1300 MW/1800 rpm)

Mixed axial-radial compressor

Gas turbine (60

– 90 MW)

Industrial gas turbine (33,3 MW/3600 rpm) with a 16

stage axial compressor and 5 stages axial turbine

Gas turbine of an airplane turbo-proppeler

Gear box

Proppeler shaft

2 stages radial compressor

Combustion chamber

3 stages axial turbine

Exit nozzle

High by-pass airplane turbo-fan

Bibliography

Chapter 1

Turbomáquinas, A. F. O. Falcão, Folhas

AEIST, 2004.