Compound engine

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Wright R-3350 Duplex-Cyclone turbo compound engine Curtiss Wright R3350-972TC-18 1.jpg
Wright R-3350 Duplex-Cyclone turbo compound engine
Bavarian S 3/6 compound locomotive, showing the two high-pressure cylinders mounted centrally in the frame and the two slightly larger low-pressure cylinders on either side Steam Engine 18 478 S 3-6 2009-10-11.jpg
Bavarian S 3/6 compound locomotive, showing the two high-pressure cylinders mounted centrally in the frame and the two slightly larger low-pressure cylinders on either side

A compound engine is an engine that has more than one stage for recovering energy from the same working fluid, with the exhaust from the first stage passing through the second stage, and in some cases then on to another subsequent stage or even stages. Originally invented as a means of making steam engines more efficient, the compounding of engines by use of several stages has also been used on internal combustion engines and continues to have niche markets there.

Contents

The stages of a compound engine may be either of differing or of similar technologies, for example:

These examples and compound turbines are the main but not the only uses of compounding in engines, see below.

Terminology

A compound engine uses several stages to produce its output.

Not all engines that use multiple stages are called compound engines. In particular, if an engine uses a later stage purely to extract energy from the exhaust for some other purpose, and notably for turbo charging, is not called a compound engine. Similarly, proposed engines that use a free piston engine to drive a turbine would not be called compound engines, as only the second stage produces output power.

However, if a turbo compound engine is also supercharged by feeding some of the shaft power back to the supercharger, as in some aircraft engines, it is still a compound engine. Usage of the terms supercharged and turbosupercharged has varied with time, for example the makers of the Wright R-3350 Duplex-Cyclone compound engine described it at the time as turbosupercharged. It is however a compound engine, and a similar engine produced today would be described as supercharged rather than turbocharged.

The term compounding is a little less restrictive than compound engine. Large compound turbines are an application of compounding, as are the multiple rows of blades used in many gas turbines, but neither is normally referred to as a compound engine. The several sets of blades in a single turbine are perhaps better thought of as similar in principle to the uniflow steam engine than to compounding. Unlike the uniflow steam engine, which has found niche uses only, multiple row turbines have found enormous practical application.

An engine that does not use compounding is referred to as a simple engine, particularly in the case of a steam locomotive, or more precisely as a simple expansion engine, particularly in the case of a marine steam engine.

Note however that in the case of any steam engine, simple engine can also be used to mean one that does not use a condenser to generate negative pressure and so improve efficiency. Use of separate condensers for this purpose is one of the key features that distinguishes the Watt steam engine of 1765 from the Newcomen steam engine of 1712.

No ambiguity arises in the case of a steam locomotive, as in a condensing steam locomotive the condenser is not there to increase efficiency, and may even reduce efficiency in order to conserve water and reduce emissions. So for example the Metropolitan Railway A Class is in every sense a simple locomotive despite its condensers, and the term simple engine applied to steam locomotives always in practice means one that does not use compounding, again irrespective of its use of condensers. The terms simple expansion locomotive and simple expansion engine are sometimes applied to locomotives to remove any possible confusion.

History

Steam

Woolf compound beam engine, 1858, with the light-coloured high- and low-pressure cylinders clearly visible Woolfsche Balanciermaschine 1858.JPG
Woolf compound beam engine, 1858, with the light-coloured high- and low-pressure cylinders clearly visible

The oldest examples of compound engines are compound steam engines. In 1805 Arthur Woolf patented the Woolf high pressure compound engine which used this principle.

Compounding was particularly used on stationary steam engines, marine steam engines, and on some steam locomotives starting from the 1850s, largely in continental Europe. [1]

Three stage or triple expansion reciprocating steam engines, with three cylinders of increasing bore in line, were quite popular for steamship propulsion. "Doctor" Alexander Carnegie Kirk, experimentally fitted his first triple expansion engine to a ship called Propontis in 1874. In 1881, Kirk installed a refined version of his engine in SS Aberdeen on Clydeside, Scotland. [2] This ship proved the advantages of power and economy of the new engine, in commercial service between the United Kingdom and the Far East. [3] The first warship to be so equipped was the Spanish warship Destructor, which was also built on Clydeside, and the first engine of this type used in ships of the Royal Navy was designed by J. W. Reed, who also created the Reed water tube boiler. [4] [5] Other navies and commercial shipowners soon followed. Four-stage, or quadruple, expansion engines were also used.

Several classes of steam locomotive have existed in both simple and compound form, most commonly when locomotives originally built as compound were converted to simple in order to gain power at the expense of efficiency, for example the majority of the NZR X class. Other conversions involved redesigning the details of the compounding, for example many compound locomotives designed by Alfred de Glehn and state of the art in their day were modified by André Chapelon to use his later scheme.

Internal combustion

Some compound internal combustion engines have been patented, but these have not met with much commercial success. these engines use a three-cylinder arrangement with alternating high-pressure cylinders exhaust into a central low-pressure cylinder.

Examples include: Deutz 1879, Forest-Gallice 1888, Connelly 1888, Diesel 1897, Bales 1897, Babled 1903, Butler 1904, Eisenhuth 1904–7, Abbot 1910. [6] The concept was "re-invented" and patented as the five-stroke engine in 2000 by Gerhard Schmitz, which was experimented with by Ilmor.

Turbo-compounding has been applied to internal combustion engines. Turbo compound engines were extensively used as aircraft engines immediately after the Second World War. [7] [8]

Diesel turbo compound engines remain in use in trucks and agricultural machinery. [9]

Examples

Napier Nomad turbo-compound aircraft engine, showing the turbine below. Modern compound truck and machinery engines use a similar configuration. Napier Nomad.jpg
Napier Nomad turbo-compound aircraft engine, showing the turbine below. Modern compound truck and machinery engines use a similar configuration.

See also

Theory

Inventors and designers

Similar technology

Related Research Articles

<span class="mw-page-title-main">Engine</span> Machine that converts one or more forms of energy into mechanical energy (of motion)

An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy.

<span class="mw-page-title-main">Steam engine</span> Engine that uses steam to perform mechanical work

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 transformed, by a connecting rod and crank, into rotational force for work. The term "steam engine" is most commonly applied to reciprocating engines as just described, although some authorities have also referred to the steam turbine and devices such as Hero's aeolipile as "steam engines". The essential feature of steam engines is that they are external combustion engines, where the working fluid is separated from the combustion products. The ideal thermodynamic cycle used to analyze this process is called the Rankine cycle. In general usage, the term steam engine can refer to either complete steam plants, such as railway steam locomotives and portable engines, or may refer to the piston or turbine machinery alone, as in the beam engine and stationary steam engine.

<span class="mw-page-title-main">Steam turbine</span> Machine that uses steam to rotate a shaft

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 turbine involves advanced metalwork to form high-grade steel alloys into precision parts using technologies that first became available in the 20th century; continued advances in durability and efficiency of steam turbines remains central to the energy economics of the 21st century.

<span class="mw-page-title-main">Turbocharger</span> Exhaust-powered forced-induction device for engines

In an internal combustion engine, a turbocharger is a forced induction device that is powered by the flow of exhaust gases. It uses this energy to compress the intake air, forcing more air into the engine in order to produce more power for a given displacement.

<span class="mw-page-title-main">Napier Nomad</span> British diesel aircraft engine

The Napier Nomad is a British diesel aircraft engine designed and built by Napier & Son in 1949. They combined a piston engine with a turbine to recover energy from the exhaust and thereby improve fuel economy. Two versions were tested, the complex Nomad I which used two propellers, each driven by the mechanically independent stages, and the Nomad II, using the turbo-compound principle, coupled the two parts to drive a single propeller. The Nomad II had the lowest specific fuel consumption figures seen up to that time. Despite this the Nomad project was cancelled in 1955 having spent £5.1 million on development, as most interest had passed to turboprop designs.

<span class="mw-page-title-main">Kylchap</span> Steam locomotive exhaust system

The Kylchap steam locomotive exhaust system was designed and patented by French steam engineer André Chapelon, using a second-stage nozzle designed by the Finnish engineer Kyösti Kylälä and known as the Kylälä spreader; thus the name KylChap for this design.

<span class="mw-page-title-main">Valve gear</span> Mechanism for controlling steam flow in a reciprocating steam engine.

The valve gear of a steam engine is the mechanism that operates the inlet and exhaust valves to admit steam into the cylinder and allow exhaust steam to escape, respectively, at the correct points in the cycle. It can also serve as a reversing gear. It is sometimes referred to as the "motion".

<span class="mw-page-title-main">Stationary steam engine</span> Fixed steam engine for pumping or power generation

Stationary steam engines are fixed steam engines used for pumping or driving mills and factories, and for power generation. They are distinct from locomotive engines used on railways, traction engines for heavy steam haulage on roads, steam cars, agricultural engines used for ploughing or threshing, marine engines, and the steam turbines used as the mechanism of power generation for most nuclear power plants.

Steam power developed slowly over a period of several hundred years, progressing through expensive and fairly limited devices in the early 17th century, to useful pumps for mining in 1700, and then to Watt's improved steam engine designs in the late 18th century. It is these later designs, introduced just when the need for practical power was growing due to the Industrial Revolution, that truly made steam power commonplace.

<span class="mw-page-title-main">Compound steam engine</span> Steam engine where steam is expanded in stages

A compound steam engine unit is a type of steam engine where steam is expanded in two or more stages. A typical arrangement for a compound engine is that the steam is first expanded in a high-pressure (HP) cylinder, then having given up heat and losing pressure, it exhausts directly into one or more larger-volume low-pressure (LP) cylinders. Multiple-expansion engines employ additional cylinders, of progressively lower pressure, to extract further energy from the steam.

<span class="mw-page-title-main">Articulated locomotive</span> Type of locomotive

An articulated locomotive is a steam locomotive with one or more engine units that can move independently of the main frame. Articulation allows the operation of locomotives that would otherwise be too large to negotiate a railroad's curves, whether mainlines or special lines with extreme curvature such as logging, industrial, or mountain railways.

André Chapelon was a French mechanical engineer and designer of advanced steam locomotives. A graduate engineer of Ecole Centrale Paris, he was one of very few locomotive designers who brought a rigorous scientific method to their design, and he sought to apply up-to-date theories and knowledge in subjects such as thermodynamics, and gas and fluid flow. Chapelon's work was an early example of what would later be called modern steam, and influenced the work of many later designers of those locomotives, such as Livio Dante Porta.

<span class="mw-page-title-main">Steam turbine locomotive</span>

A steam turbine locomotive was a steam locomotive which transmitted steam power to the wheels via a steam turbine. Numerous attempts at this type of locomotive were made, mostly without success. In the 1930s this type of locomotive was seen as a way both to revitalize steam power and challenge the diesel locomotives then being introduced.

<span class="mw-page-title-main">Condensing steam locomotive</span> Type of locomotive designed to recover exhaust steam

A condensing steam locomotive is a type of locomotive designed to recover exhaust steam, either in order to improve range between taking on boiler water, or to reduce emission of steam inside enclosed spaces. The apparatus takes the exhaust steam that would normally be used to produce a draft for the firebox, and routes it through a heat exchanger, into the boiler water tanks. Installations vary depending on the purpose, design and the type of locomotive to which it is fitted. It differs from the usual closed cycle condensing steam engine, in that the function of the condenser is primarily either to recover water, or to avoid excessive emissions to the atmosphere, rather than maintaining a vacuum to improve both efficiency and power.

Engine efficiency of thermal engines is the relationship between the total energy contained in the fuel, and the amount of energy used to perform useful work. There are two classifications of thermal engines-

  1. Internal combustion and
  2. External combustion engines.
<span class="mw-page-title-main">Uniflow steam engine</span> Type of steam engine

The uniflow type of steam engine uses steam that flows in one direction only in each half of the cylinder. Thermal efficiency is increased by having a temperature gradient along the cylinder. Steam always enters at the hot ends of the cylinder and exhausts through ports at the cooler centre. By this means, the relative heating and cooling of the cylinder walls is reduced.

<span class="mw-page-title-main">Two-stroke diesel engine</span> Engine type

A two-stroke diesel engine is a diesel engine that uses compression ignition in a two-stroke combustion cycle. It was invented by Hugo Güldner in 1899.

A compound locomotive is a steam locomotive which is powered by a compound engine, a type of steam engine where steam is expanded in two or more stages. The locomotive was only one application of compounding. Two and three stages were used in ships, for example.

<span class="mw-page-title-main">Marine steam engine</span> Steam engine that is used to power a ship or boat

A marine steam engine is a steam engine that is used to power a ship or boat. This article deals mainly with marine steam engines of the reciprocating type, which were in use from the inception of the steamboat in the early 19th century to their last years of large-scale manufacture during World War II. Reciprocating steam engines were progressively replaced in marine applications during the 20th century by steam turbines and marine diesel engines.

<span class="mw-page-title-main">Internal combustion engine</span> Engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber

An internal combustion engine is a heat engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combustion engine, the expansion of the high-temperature and high-pressure gases produced by combustion applies direct force to some component of the engine. The force is typically applied to pistons, turbine blades, a rotor, or a nozzle. This force moves the component over a distance, transforming chemical energy into kinetic energy which is used to propel, move or power whatever the engine is attached to.

References

  1. The Evolution of Compound Locomotives http://mikes.railhistory.railfan.net/r043.html retrieved 7 December 2012
  2. Day, Lance and McNeil, Ian (Editors) 2013, Biographical Dictionary of the History of Technology Routledge, ISBN   0-203-02829-5 (P. 694)
  3. "The Friends of Dundee City Archives - Marine Engineering 1814-1984 by David Middleton". Archived from the original on 2017-12-09. Retrieved 2013-08-08.
  4. Macksey, Kenneth Technology in War, ISBN   0-85368-825-7 p38
  5. Anon. (18 March 1932). "The late Mr J. W. Reed" (PDF). The Engineer: 303. OCLC   5743177. Archived (PDF) from the original on 15 February 2017. Retrieved 15 February 2017.
  6. "Compound Internal Combustion Engines".
  7. 1 2 http://www.enginehistory.org/Wright/Kuhns/CurtissWrightTC18/TurboCompounds.shtml Archived 2016-11-08 at the Wayback Machine retrieved 9 December 2012
  8. 1 2 http://www.superconstellation.org/TechnicalInformation/motor/motor-en.html Archived 2018-10-20 at the Wayback Machine retrieved 9 December 2012
  9. http://www.demanddetroit.com/pdf/engines/2007-dd15-brochure.pdf%5B%5D retrieved 7 December 2012 Fifty free horsepower customer brochure
  10. 1941 Locomotive Cyclopedia of American Practice, Eleventh Edition, Simmons-Boardman Publishing Corporation, 30 Church Street, New York p.813
  11. http://www.der-wankelmotor.de/Motoren/Rolls-Royce/rolls-royce.html (in German) retrieved 7 December 2012