Turbine

Turbine is a rotary machine that converts the energy contained in a moving fluid into mechanical rotational energy.  The fluid may be a liquid, such as water, or a gas, such as steam, combustion gases, or air.  As the fluid flows through or over specially designed blades attached to a rotating wheel called a rotor, it transfers part of its energy to the rotor, causing the shaft connected to the rotor to spin.  The rotating shaft can then be used directly to drive machinery such as pumps, compressors, and generators, or it can be used to produce electricity through an electrical generator.

A turbine is based on the conservation of energy and the transfer of momentum from a flowing fluid to rotating blades.  The fluid possesses energy in the form of pressure energy, kinetic energy, thermal energy, or a combination of these forms.  As the fluid passes through the turbine, some of this energy is extracted and converted into useful mechanical work.  The fluid exits the turbine with less energy than it had at the inlet because a portion of its energy has been transferred to the rotating shaft.

Turbines are important energy conversion devices used in industry and power generation.  Water turbines are used in hydroelectric facilities to convert the energy of flowing or falling water into mechanical power.  Steam turbines are widely used in fossil fuel, nuclear, geothermal, and solar thermal power plants, where high-pressure steam drives the turbine.  Gas turbines use high-temperature combustion gases to produce rotational power and are commonly used in power generation and aircraft propulsion.  Wind turbines convert the kinetic energy of moving air into rotational energy and subsequently into electricity.

A turbine is classified as a type of rotating equipment because its primary operating component is a rotating rotor assembly.  Turbines are designed to operate at specific flow rates, pressures, temperatures, and rotational speeds to achieve high efficiency and reliable performance.  Their design involves fluid dynamics, thermodynamics, heat transfer, materials engineering, and mechanical design principles.

Turbine Types

Water Turbine Types

Pelton Turbine  -  An impulse turbine used for high-head, low-flow applications.
Turgo Turbine  -  An impulse turbine similar to the Pelton turbine.
Cross-Flow Turbine (Banki-Michell Turbine)  -  An impulse turbine in which water passes through the runner twice.
Francis Turbine  -  A reaction turbine used for medium-head applications.
Kaplan Turbine  -  An axial-flow reaction turbine with adjustable blades.
Propeller Turbine  -  An axial-flow reaction turbine with fixed blades.
Bulb Turbine  -  A low-head axial-flow reaction turbine.

Steam Turbine Types

Impulse Steam Turbine  -  Energy conversion occurs primarily through velocity changes across the moving blades.
Reaction Steam Turbine  -  Energy conversion occurs through both pressure and velocity changes within the moving blades.
Condensing Steam Turbine  -  Exhaust steam is discharged to a condenser.
Back-Pressure Steam Turbine  -  Exhaust steam leaves at a pressure higher than atmospheric pressure.
Extraction Steam Turbine  -  Steam is extracted from intermediate stages for process use.
Reheat Steam Turbine  -  Steam is reheated between turbine stages.

Gas Turbine Types

Open-Cycle Gas Turbine  -  Air enters, combustion occurs, and exhaust gases are discharged to the atmosphere.
Closed-Cycle Gas Turbine  -  The working fluid circulates in a closed loop.
Single-Shaft Gas Turbine  -  Compressor and turbine are mounted on one shaft.
Two-Shaft Gas Turbine  -  Includes a separate power turbine.

Wind Turbine Types

Horizontal-Axis Wind Turbine (HAWT)  -  Rotor axis is parallel to the ground.
Vertical-Axis Wind Turbine (VAWT)  -  Rotor axis is perpendicular to the ground.

Classification by Operating Principle

Impulse Turbine  -  Fluid pressure is converted into velocity before entering the runner; the runner operates primarily under kinetic energy.
Reaction Turbine  -  Pressure drop occurs across both stationary and rotating blades, and the runner operates while fully immersed in the fluid.

Classification by Flow Direction Through the Runner

Axial-Flow Turbine  -  Fluid flows parallel to the shaft axis.
Radial-Flow Turbine  -  Fluid flows radially inward or outward.
Mixed-Flow Turbine  -  Fluid flows through both radial and axial directions.
Tangential-Flow Turbine  -  Fluid enters tangentially to the runner.