Ingeniero

Aerodynamics of Propellers Aerodynamics of Propellers and Wind Turbine Rotors and Wind Turbine Rotors
Lecture within the course

Fluid Machinery (4A1629)
Miroslav Petrov, Lic. of Eng.
Division of Heat and Power, Department of Energy Technology, KTH

Dept. of Energy Technology, Stockholm, Sweden. Course “Fluid Machinery” (4A1629)

1

Structure of the presentation Structure of thepresentation
1. Introduction and terminology reminder. 2. Basic theory of propellers and their application. 3. Basic wind turbine aerodynamics. The Betz limit. 4. Real wind turbine rotors with 2-D and 3-D effects. 5. Aspects of vertical axis wind turbines.

Dept. of Energy Technology, Stockholm, Sweden. Course “Fluid Machinery” (4A1629)

2

Section 1 Section 1

Introduction and TerminologyReminder

Dept. of Energy Technology, Stockholm, Sweden. Course “Fluid Machinery” (4A1629)

3

Variety of Fluid Machines Variety of Fluid Machines
Please remember that:
Turbomachines (rotodynamic machines) convert the energy in a fluid stream directly into mechanical energy of rotating shaft, or vice versa. Mechanical energy is converted into energy of fluid streams by pumps, compressors,propellers and fans/ventilators – various names depending on fluid type, application and pressure ratio. Energy from fluid streams is converted into mechanical energy of a rotating shaft by turbines – they are always called “turbines” independent of fluid type, application or pressure ratio. All fluid machines are completely reversible!!! (For example, pumps, propellers or fans can easily betransformed into turbines).

Dept. of Energy Technology, Stockholm, Sweden. Course “Fluid Machinery” (4A1629)

4

Application of propellers Application of propellers
Propellers are used to produce propulsive thrust in ships and aircraft, therefore their name. Modern airplane propellers are driven by gas turbines in so-called turboprop engines. Propellers deliver also both lift and propulsivethrust for helicopters. Modern helicopter rotors are driven by gas turbines in so-called turboshaft engines.
Propeller-driven aircraft have a limit in possible cruising speeds of around 650 km/h.

Propeller-type rotors are also commonly used in axial fans (ventilators) typically applied for very low pressure ratios at high mass flows.

Dept. of Energy Technology, Stockholm, Sweden. Course “FluidMachinery” (4A1629)

5

Jet engines: no propeller Jet engines: no propeller
Jet engines produce propulsion thrust by way of expansion of a jet stream through a nozzle. The compressed working fluid is generated by a turbomachine – a gas turbine driving a compressor.

Source: www.globemaster.de/airextreme/

Dept. of Energy Technology, Stockholm, Sweden. Course “Fluid Machinery” (4A1629)

6Ship and Airplane Propellers Ship and Airplane Propellers
Propellers produce propulsive thrust by utilizing the lift forces acting on rotating blades of aerofoil shape. A slipstream of accelerated fluid is formed behind the propeller. Any type of engine can be used to drive the propeller (all possible prime-mover types are used for marine transport, while mostly gas turbines or Otto-typeinternal combustion engines are used for airborn transport).
Propellers (airscrews) for airplanes

Propellers (screws) for ships and boats

Source: www.customshippropellers.com

Source: www.saab.se

Dept. of Energy Technology, Stockholm, Sweden. Course “Fluid Machinery” (4A1629)

7

Helicopter rotors Helicopter rotors
The propeller of a helicopter produces both lifting force andpropulsive thrust. The slipstream of accelerated fluid flows downward around the machine’s body. If the main rotor is only one, a small additional propeller is required at the back of the helicopter to neutralize the torque induced by the main rotor.

Source: www.globemaster.de/airextreme/

Dept. of Energy Technology, Stockholm, Sweden. Course “Fluid Machinery” (4A1629)

8

Reversibility of...