thumb|Mounting of a [[steam turbine produced by Siemens, Germany]]

thumb|Aircraft engine, in this case on a [[Boeing 777]]

Turbomachinery, in mechanical engineering, describes machines that transfer energy between a rotor and a fluid, including both turbines and compressors. While a turbine transfers energy from a fluid to a rotor, a compressor transfers energy from a rotor to a fluid. It is an important application of fluid mechanics.

These two types of machines are governed by the same basic relationships including Newton's second law of motion and Euler's pump and turbine equation for compressible fluids. Centrifugal pumps are also turbomachines that transfer energy from a rotor to a fluid, usually a liquid, while turbines and compressors usually work with a gas. Then the first functioning industrial gas turbines were used in the late 1890s to power street lights (Meher-Homji, 2000).

Classification

thumb|A steam turbine from [[MAN SE subsidiary MAN Turbo]]

In general, the two kinds of turbomachines encountered in practice are open and closed turbomachines. Open machines such as propellers, windmills, and unshrouded fans act on an infinite extent of fluid, whereas closed machines operate on a finite quantity of fluid as it passes through a housing or casing.

{|class="wikitable"

|+ Classification of fluid machinery in species and groups

|-

!!!Machinery!!Combinations of power and machinery!!Engines

|-

!Open turbomachine

| Propeller || ||Wind turbines

|-

!Hydraulic fluid<br />machinery<br />(≈ incompressible<br />fluids)

|Centrifugal pumps,<br />turbopumps,<br />fans||Fluid couplings and clutches<br />(hydrodynamic gearboxes);<br />Voith turbo transmissions;<br />pump–turbines<br />(in pumped-storage hydroelectricity)||Water turbines

|-

!Thermal<br />turbomachinery<br />(compressible fluid)

|Compressors||Gas turbines<br />(Inlet consists of a compressor.)||Steam turbines,<br />turbojet engines

|}

Turbomachines

Definition

Any device that extracts energy from or imparts energy to a continuously moving stream of fluid can be called a turbomachine. Elaborating, a turbomachine is a power or heat generating machine which employs the dynamic action of a rotating element, the rotor; the action of the rotor changes the energy level of the continuously flowing fluid through the machine. Turbines, compressors and fans are all members of this family of machines.

In contrast to positive displacement machines (particularly of the reciprocating type which are low speed machines based on the mechanical and volumetric efficiency considerations), the majority of turbomachines run at comparatively higher speeds without any mechanical problems and volumetric efficiency close to one hundred percent.

Categorization

Energy conversion

Turbomachines can be categorized on the basis of the direction of energy conversion:

[[File:Axial Turbomachine's Velocity Diagram.svg|thumb|centre|Velocity diagram of an axial turbomachine The radial component of the fluid velocity is negligible. Since there is no change in the direction of the fluid, several axial stages can be used to increase power output.

A Kaplan turbine is an example of an axial flow turbine.

In the figure:

  • U = Blade velocity,
  • V<sub>f</sub> = Flow velocity,
  • V = Absolute velocity,
  • V<sub>r</sub> = Relative velocity,
  • V<sub>w</sub> = Tangential or Whirl component of velocity.

thumb|centre| Velocity diagram of a radial turbomachine Water jets are best suited to fast vessels and are thus used often by the military. Water jet propulsion has many advantages over other forms of marine propulsion, such as [[Sterndrive|stern drives, outboard motors, shafted propellers and surface drives.

Auto

thumb|Air and exhaust flow through engine and turbocharger

Turbochargers – Turbochargers are one of the most popular turbomachines. They are used mainly for adding power to engines by adding more air. It combines both forms of turbomachines. Exhaust gases from the engine spin a bladed wheel, much like a turbine. That wheel then spins another bladed wheel, sucking and compressing outside air into the engine.

Superchargers – Superchargers are used for engine-power enhancement as well, but only work off the principle of compression. They use the mechanical power from the engine to spin a screw or vane, some way to suck in and compress the air into the engine.

General

Pumps – Pumps are another very popular turbomachine. Although there are very many different types of pumps, they all do the same thing. Pumps are used to move fluids around using some sort of mechanical power, from electric motors to full size diesel engines. Pumps have thousands of uses, and are the true basis to turbomachinery (Škorpík, 2017).

Air compressors – Air compressors are another very popular turbomachine. They work on the principle of compression by sucking in and compressing air into a holding tank. Air compressors are one of the most basic turbomachines.

Fans – Fans are the most general type of turbomachines.

Aerospace

Gas turbines – Aerospace gas turbines, more commonly known as jet engines, are the most common gas turbines.

Turbopumps – Rocket engines require very high propellant pressures and mass flow rates, meaning their pumps require a lot of power. One of the most common solutions to this issue is to use a turbopump that extracts energy from an energetic fluid flow. The source of this energetic fluid flow could be one or a combination of many things, including the decomposition of hydrogen peroxide, the combustion of a portion of the propellants, or even the heating of cryogenic propellants run through coolant jackets in the combustion chamber's walls.

Partial list of turbomachine topics

Many types of dynamic continuous flow turbomachinery exist. Below is a partial list of these types. What is notable about these turbomachines is that the same fundamentals apply to all. Certainly there are significant differences between these machines and between the types of analysis that are typically applied to specific cases. This does not negate the fact that they are unified by the same underlying physics of fluid dynamics, gas dynamics, aerodynamics, hydrodynamics, and thermodynamics.

  • Axial compressor
  • Axial fan
  • Centrifugal compressor
  • Centrifugal fan
  • Centrifugal pump
  • Centrifugal-type supercharger
  • Exoskeletal engine
  • Francis turbine
  • Gas turbine
  • Industrial fans
  • Jet engine
  • Mechanical fan
  • Mixed flow compressor
  • Radial turbine
  • Steam turbine
  • Turbocharger
  • Turboexpander
  • Turbofans
  • Turbojet
  • Turboprop
  • Turbopump
  • Turboshaft
  • Turbines
  • Water turbine

See also

  • Blade solidity
  • Secondary flow in turbomachinery
  • Slip factor
  • Three-dimensional losses and correlation in turbomachinery

References

Sources

  • S. M. Yahya. "Turbines Compressors and Fans". 1987. McGraw Hill.
  • Nagpurwala, Q. (n.d.). Steam Turbines. Retrieved April 10, 2017, from <nowiki>http://164.100.133.129:81/eCONTENT/Uploads/13-Steam%20Turbines%20%5BCompatibility%20Mode%5D.pdf</nowiki>
  • Soares, C. M. (n.d.). GAS TURBINES IN SIMPLE CYCLE & COMBINED CYCLE APPLICATIONS. 1-72. Retrieved April 10, 2017, from <nowiki>https://www.netl.doe.gov/File%20Library/Research/Coal/energy%20systems/turbines/handbook/1-1.pdf</nowiki>
  • Perlman, U. H. (2016, December 2). Hydroelectric power: How it works. Retrieved April 10, 2017, from <nowiki>https://water.usgs.gov/edu/hyhowworks.html</nowiki>
  • Škorpík, J. (2017, January 1). Lopatkový stroj-English version. Retrieved April 9, 2017, from <nowiki>http://www.transformacni-technologie.cz/en_11.html</nowiki>
  • Kayadelen, H. (2013). Marine Gas Turbines. 7th International Advanced Technologies Symposium. Retrieved April 15, 2017.
  • Hydrodynamics of Pumps
  • Ctrend website to calculate the head of centrifugal compressor online