Turbomachinery, in

mechanical engineering Mechanical engineering is the study of physical machines that may involve force and movement. It is an engineering branch that combines engineering physics and mathematics principles with materials science, to design, analyze, manufacture, ...

, describes

machine A machine is a physical system using power to apply forces and control movement to perform an action. The term is commonly applied to artificial devices, such as those employing engines or motors, but also to natural biological macromolecul ...

s that transfer

energy In physics, energy (from Ancient Greek: ἐνέργεια, ''enérgeia'', “activity”) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of ...

between a

rotor Rotor may refer to: Science and technology Engineering * Rotor (electric), the non-stationary part of an alternator or electric motor, operating with a stationary element so called the stator *Helicopter rotor, the rotary wing(s) of a rotorcraft ...

and a

fluid In physics, a fluid is a liquid, gas, or other material that continuously deforms (''flows'') under an applied shear stress, or external force. They have zero shear modulus, or, in simpler terms, are substances which cannot resist any shear ...

, including both

turbines A turbine ( or ) (from the Greek , ''tyrbē'', or Latin ''turbo'', meaning vortex) is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful Work (physics), work. The work produced by a turbine can be used ...

and

compressors A compressor is a mechanical device that increases the pressure of a gas by reducing its volume. An air compressor is a specific type of gas compressor. Compressors are similar to pumps: both increase the pressure on a fluid and both can trans ...

. While a turbine transfers energy from a fluid to a rotor, a compressor transfers energy from a rotor to a fluid.Logan, Earl. "Handbook of turbomachinery". 1995. Marcel Deckker.Vandad Talimi (Original author unknown). "Mechanical Equipment and Systems". 2013. Memorial University of Newfoundland. http://www.engr.mun.ca/~yuri/Courses/MechanicalSystems/Turbomachinery.pdf These two types of machines are governed by the same basic relationships including

Newton's second Law of Motion Newton's laws of motion are three basic Scientific law, laws of classical mechanics that describe the relationship between the motion of an object and the forces acting on it. These laws can be paraphrased as follows: # A body remains at re ...

and

Euler's pump and turbine equation The Euler pump and turbine equations are the most fundamental equations in the field of turbomachinery. These equations govern the power, efficiencies and other factors that contribute to the design of turbomachines. With the help of these equation ...

for

compressible fluid Compressible flow (or gas dynamics) is the branch of fluid mechanics that deals with flows having significant changes in fluid density. While all flows are compressible, flows are usually treated as being incompressible when the Mach number (t ...

Centrifugal pump Centrifugal pumps are used to transport fluids by the conversion of rotational kinetic energy to the hydrodynamic energy of the fluid flow. The rotational energy typically comes from an engine or electric motor. They are a sub-class of dynamic ...

s are also turbomachines that transfer energy from a rotor to a fluid, usually a liquid, while turbines and compressors usually work with a gas.

History

The first turbomachines could be identified as

water wheel A water wheel is a machine for converting the energy of flowing or falling water into useful forms of power, often in a watermill. A water wheel consists of a wheel (usually constructed from wood or metal), with a number of blades or buckets ...

s, which appeared between the 3rd and 1st centuries BCE in the Mediterranean region. These were used throughout the medieval period and began the first

Industrial Revolution The Industrial Revolution was the transition to new manufacturing processes in Great Britain, continental Europe, and the United States, that occurred during the period from around 1760 to about 1820–1840. This transition included going f ...

. When

steam power A steam engine is a heat engine that performs mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a cylinder. This pushing force can be tra ...

started to be used, as the first power source driven by the combustion of a fuel rather than renewable natural power sources, this was as

reciprocating engine A reciprocating engine, also often known as a piston engine, is typically a heat engine that uses one or more reciprocating pistons to convert high temperature and high pressure into a rotating motion. This article describes the common fe ...

s. Primitive turbines and conceptual designs for them, such as the

smoke jack A roasting jack is a machine which rotates meat roasting on a spit. It can also be called a spit jack, a spit engine or a turnspit, although this name can also refer to a human turning the spit, or a turnspit dog. Cooking meat on a spit dates b ...

, appeared intermittently but the temperatures and pressures required for a practically efficient turbine exceeded the manufacturing technology of the time. The first patent for gas turbines were filed in 1791 by John Barber. Practical hydroelectric water turbines and steam turbines did not appear until the 1880s. Gas turbines appeared in the 1930s. The first impulse type turbine was created by Carl Gustaf de Laval in 1883. This was closely followed by the first practical reaction type turbine in 1884, built by Charles Parsons. Parsons’ first design was a multi-stage axial-flow unit, which

George Westinghouse George Westinghouse Jr. (October 6, 1846 – March 12, 1914) was an American entrepreneur and engineer based in Pennsylvania who created the railway air brake and was a pioneer of the electrical industry, receiving his first patent at the age ...

acquired and began manufacturing in 1895, while

General Electric General Electric Company (GE) is an American multinational conglomerate founded in 1892, and incorporated in New York state and headquartered in Boston. The company operated in sectors including healthcare, aviation, power, renewable ene ...

acquired de Laval's designs in 1897. Since then, development has skyrocketed from Parsons’ early design, producing 0.746 kW, to modern nuclear steam turbines producing upwards of 1500 MW. Today, steam turbines account for roughly 90% of electrical power generated in the United States. Then the first functioning industrial gas turbines were used in the late 1890s to power street lights (Meher-Homji, 2000).

Classification

In general, the two kinds of turbomachines encountered in practice are open and closed turbomachines. Open machines such as

propeller A propeller (colloquially often called a screw if on a ship or an airscrew if on an aircraft) is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral which, when rotated, exerts linear thrust upon ...

windmill A windmill is a structure that converts wind power into rotational energy using vanes called sails or blades, specifically to mill grain (gristmills), but the term is also extended to windpumps, wind turbines, and other applications, in some ...

s, 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. Turbomachines are also categorized according to the type of flow. When the flow is parallel to the

axis of rotation Rotation around a fixed axis is a special case of rotational motion. The fixed- axis hypothesis excludes the possibility of an axis changing its orientation and cannot describe such phenomena as wobbling or precession. According to Euler's r ...

, they are called axial flow machines, and when flow is perpendicular to the axis of rotation, they are referred to as radial (or centrifugal) flow machines. There is also a third category, called mixed flow machines, where both radial and axial flow velocity components are present. Turbomachines may be further classified into two additional categories: those that absorb energy to increase the

fluid pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and e ...

, i.e.

pump A pump is a device that moves fluids (liquids or gases), or sometimes slurries, by mechanical action, typically converted from electrical energy into hydraulic energy. Pumps can be classified into three major groups according to the method they ...

s, fans, and

, and those that produce energy such as

turbine A turbine ( or ) (from the Greek , ''tyrbē'', or Latin ''turbo'', meaning vortex) is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work. The work produced by a turbine can be used for generating ...

s by expanding flow to lower pressures. Of particular interest are applications which contain pumps, fans, compressors and turbines. These components are essential in almost all mechanical equipment systems, such as power and refrigeration cycles.Baskharone, E. A. "Principles of Turbomachinery in Air-Breathing Engines". 2006. Cambridge University Press. 580 pages.

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 head 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.Rajadurai, J. S. "Thermodynamics and thermal engineering". 2003. New Age International. 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."Combining Support Vector Machines and Segmentation Algorithms for Efficient Anomaly Detection: A Petroleum Industry Application". International Joint Conference SOCO’14-CISIS’14-ICEUTE’14. 2014. pp.269-278.

Categorization

Energy conversion

Turbomachines can be categorized on the basis of the direction of energy conversion: * Absorb power to increase the fluid pressure or head (ducted Fans, compressors and pumps). * Produce power by expanding fluid to a lower pressure or head (hydraulic, steam and gas turbines).

Fluid flow

Turbomachines can be categorized on the basis of the nature of flow path through the passage of the rotor:Wills, J. George. "Lubrication fundamentals". 1980. Mobil oil corporation. Marcel Dekker. 460 pages. Axial Turbomachine's Velocity Diagram

'' Axial flow turbomachines'' - When the path of the through-flow is wholly or mainly parallel to the axis of rotation, the device is termed an axial flow turbomachine.Dixon, S. L. "Fluid mechanics and thermodynamics of turbomachinery". 1998. Elsevier. 460 pages. 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 The Kaplan turbine is a propeller-type water turbine which has adjustable blades. It was developed in 1913 by Austrian professor Viktor Kaplan, who combined automatically adjusted propeller blades with automatically adjusted wicket gates to ach ...

is an example of an axial flow turbine. In the figure: *U = Blade velocity, *V_f = Flow velocity, *V = Absolute velocity, *V_r = Relative velocity, *V_w = Tangential or Whirl component of velocity. Radial Turbomachine's Velocity Diagram

'' Radial flow turbomachines'' - When the path of the throughflow is wholly or mainly in a plane perpendicular to the rotation axis, the device is termed a radial flow turbomachine. Therefore, the change of radius between the entry and the exit is finite. A Radial turbomachine can be inward or outward flow type depending on the purpose that needs to be served. Outward flow type increases the energy level of the fluid and vice versa. Due to continuous change in direction, several radial stages are generally not used. A

centrifugal pump Centrifugal pumps are used to transport fluids by the conversion of rotational kinetic energy to the hydrodynamic energy of the fluid flow. The rotational energy typically comes from an engine or electric motor. They are a sub-class of dynamic ...

is an example of a radial flow turbomachine. '' Mixed flow turbomachines'' – When axial and radial flow are both present and neither is negligible, the device is termed a mixed flow turbomachine. It combines flow and force components of both radial and axial types. A

Francis turbine The Francis turbine is a type of water turbine. It is an inward-flow reaction turbine that combines radial and axial flow concepts. Francis turbines are the most common water turbine in use today, and can achieve over 95% efficiency. The proc ...

is an example of a mixed-flow turbine.

Physical action

Turbomachines can finally be classified on the relative magnitude of the pressure changes that take place across a stage: An Impulse Turbomachine Stage

''Impulse Turbomachines'' operate by accelerating and changing the flow direction of fluid through a stationary

nozzle A nozzle is a device designed to control the direction or characteristics of a fluid flow (specially to increase velocity) as it exits (or enters) an enclosed chamber or pipe. A nozzle is often a pipe or tube of varying cross sectional area, ...

(the stator blade) onto the rotor blade. The nozzle serves to change the incoming pressure into velocity, the

enthalpy Enthalpy , a property of a thermodynamic system, is the sum of the system's internal energy and the product of its pressure and volume. It is a state function used in many measurements in chemical, biological, and physical systems at a constant ...

of the fluid decreases as the velocity increases. Pressure and enthalpy drop over the rotor blades is minimal. Velocity will decrease over the rotor.

Newton's second law Newton's laws of motion are three basic laws of classical mechanics that describe the relationship between the motion of an object and the forces acting on it. These laws can be paraphrased as follows: # A body remains at rest, or in mo ...

describes the transfer of energy. Impulse turbomachines do not require a pressure casement around the rotor since the fluid jet is created by the nozzle prior to reaching the blading on the rotor. A

Pelton wheel The Pelton wheel or Pelton Turbine is an impulse-type water turbine invented by American inventor Lester Allan Pelton in the 1870s. The Pelton wheel extracts energy from the impulse of moving water, as opposed to water's dead weight like the tra ...

is an impulse design. A Reaction Turbomachine Stage

''Reaction Turbomachines'' operate by reacting to the flow of fluid through aerofoil shaped rotor and stator blades. The velocity of the fluid through the sets of blades increases slightly (as with a nozzle) as it passes from rotor to stator and vice versa. The velocity of the fluid then decreases again once it has passed between the gap. Pressure and enthalpy consistently decrease through the sets of blades. Newton's third law describes the transfer of energy for reaction turbines. A pressure casement is needed to contain the working fluid. For compressible working fluids, multiple turbine stages are usually used to harness the expanding gas efficiently. Most turbomachines use a combination of impulse and reaction in their design, often with impulse and reaction parts on the same blade.

Dimensionless ratios to describe turbomachinery

The following dimensionless ratios are often used for the characterisation of fluid machines. They allow a comparison of flow machines with different dimensions and boundary conditions. #Pressure range ψ #Flow coefficient φ (including delivery or volume number called) #Performance numbers λ #Run number σ #Diameter Number δ

Applications

Power Generation

Hydro electric- Hydro-electric turbomachinery uses potential energy stored in water to flow over an open impeller to turn a generator which creates electricity Steam turbines- Steam turbines used in power generation come in many different variations. The overall principle is high pressure steam is forced over blades attached to a shaft, which turns a generator. As the steam travels through the turbine, it passes through smaller blades causing the shaft to spin faster, creating more electricity. Gas turbines- Gas turbines work much like steam turbines. Air is forced in through a series of blades that turn a shaft. Then fuel is mixed with the air and causes a combustion reaction, increasing the power. This then causes the shaft to spin faster, creating more electricity. Windmills- Also known as a wind turbine, windmills are increasing in popularity for their ability to efficiently use the wind to generate electricity. Although they come in many shapes and sizes, the most common one is the large three-blade. The blades work on the same principle as an airplane wing. As wind passes over the blades, it creates an area of low and high pressure, causing the blade to move, spinning a shaft and creating electricity. It is most like a steam turbine, but works with an infinite supply of wind.

Marine

Steam turbine- Steam turbines in marine applications are very similar to those in power generation. The few differences between them are size and power output. Steam turbines on ships are much smaller because they don't need to power a whole town. They aren't very common because of their high initial cost, high specific fuel consumption, and expensive machinery that goes with it. Gas turbines- Gas turbines in marine applications are becoming more popular due to their smaller size, increased efficiency, and ability to burn cleaner fuels. They run just like gas turbines for power generation, but are also much smaller and do require more machinery for propulsion. They are most popular in naval ships as they can be at a dead stop to full power in minutes (Kayadelen, 2013), and are much smaller for a given amount of power.

Water jet Water jet may refer to: * A jet of water under pressure, like in an ornamental fountain * Pump-jet, a marine propulsion mechanism for jetskis and other types of boats * Water jet cutter, a tool for cutting and the machining of engineering material ...

- Essentially a waterjet drive is like an aircraft turbojet with the difference that the operating fluid is water instead of air. 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 stern drives, outboard motors, shafted propellers and surface drives.

Auto

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 An axial compressor is a gas compressor that can continuously pressurize gases. It is a rotating, airfoil-based compressor in which the gas or working fluid principally flows parallel to the axis of rotation, or axially. This differs from other ...

Axial fan A fan is a powered machine used to create a flow of air. A fan consists of a rotating arrangement of vanes or blades, generally made of wood, plastic, or metal, which act on the air. The rotating assembly of blades and hub is known as an '' ...

Centrifugal compressor Centrifugal compressors, sometimes called impeller compressors or radial compressors, are a sub-class of dynamic axisymmetric work-absorbing turbomachinery. They achieve pressure rise by adding energy to the continuous flow of fluid through t ...

Centrifugal fan A centrifugal fan is a mechanical device for moving air or other gases in a direction at an angle to the incoming fluid. Centrifugal fans often contain a ducted housing to direct outgoing air in a specific direction or across a heat sink; such ...

Centrifugal type supercharger A centrifugal supercharger is a specialized type of supercharger that makes use of centrifugal force in order to increase the manifold air pressure, MAP. An increased MAP allows the engine to burn more fuel, which results in an increased power outpu ...

Exoskeletal engine The exoskeletal engine (ESE) is a concept in turbomachinery design. Current gas turbine engines have central rotating shafts and fan-discs and are constructed mostly from heavy metals. They require lubricated bearings and need extensive cooling for ...

Gas turbine A gas turbine, also called a combustion turbine, is a type of continuous flow internal combustion engine. The main parts common to all gas turbine engines form the power-producing part (known as the gas generator or core) and are, in the directio ...

* Industrial fans *

Jet engine A jet engine is a type of reaction engine discharging a fast-moving jet (fluid), jet of heated gas (usually air) that generates thrust by jet propulsion. While this broad definition can include Rocket engine, rocket, Pump-jet, water jet, and ...

Mechanical fan A fan is a powered machine used to create a flow of air. A fan consists of a rotating arrangement of vanes or blades, generally made of wood, plastic, or metal, which act on the air. The rotating assembly of blades and hub is known as an ''im ...

Mixed flow compressor A mixed flow compressor, or diagonal compressor, combines axial and radial components to produce a diagonal airflow compressor stage. The exit mean radius is greater than at the inlet, like a centrifugal design, but the flow tends to exit in an axi ...

Radial turbine A radial turbine is a turbine in which the flow of the working fluid is radial to the shaft. The difference between axial and radial turbines consists in the way the fluid flows through the components (compressor and turbine). Whereas for an axial t ...

Steam turbine A steam turbine is a machine that extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft. Its modern manifestation was invented by Charles Parsons in 1884. Fabrication of a modern steam tu ...

Turbocharger In an internal combustion engine, a turbocharger (often called a turbo) is a forced induction device that is powered by the flow of exhaust gases. It uses this energy to compress the intake gas, forcing more air into the engine in order to pro ...

Turboexpander A turboexpander, also referred to as a turbo-expander or an expansion turbine, is a centrifugal or axial-flow turbine, through which a high-pressure gas is expanded to produce work that is often used to drive a compressor or generator. Because ...

Turbofans The turbofan or fanjet is a type of airbreathing jet engine that is widely used in aircraft engine, aircraft propulsion. The word "turbofan" is a portmanteau of "turbine" and "fan": the ''turbo'' portion refers to a gas turbine engine which ac ...

Turbojet The turbojet is an airbreathing jet engine which is typically used in aircraft. It consists of a gas turbine with a propelling nozzle. The gas turbine has an air inlet which includes inlet guide vanes, a compressor, a combustion chamber, a ...

Turboprop A turboprop is a turbine engine that drives an aircraft propeller. A turboprop consists of an intake, reduction gearbox, compressor, combustor, turbine, and a propelling nozzle. Air enters the intake and is compressed by the compressor. ...

Turbopump A turbopump is a propellant pump with two main components: a rotodynamic pump and a driving gas turbine, usually both mounted on the same shaft, or sometimes geared together. They were initially developed in Germany in the early 1940s. The purpo ...

Turboshaft A turboshaft engine is a form of gas turbine that is optimized to produce shaftpower rather than jet thrust. In concept, turboshaft engines are very similar to turbojets, with additional turbine expansion to extract heat energy from the exhaust ...

Turbines A turbine ( or ) (from the Greek , ''tyrbē'', or Latin ''turbo'', meaning vortex) is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful Work (physics), work. The work produced by a turbine can be used ...

Water turbine A water turbine is a rotary machine that converts kinetic energy and potential energy of water into mechanical work. Water turbines were developed in the 19th century and were widely used for industrial power prior to electrical grids. Now, ...

References

Sources

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

External links

{{commons category, Turbomachinery
Hydrodynamics of PumpsCtrend website to calculate the head of centrifugal compressor online
Mechanical engineering Gas technologies