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Text 2. Turbines operation and purposes
Steam turbines are used for the generation of electricity in thermal power plants such as plants using coal, fuel, oil or nuclear power. They were once used to directly drive mechanical devices such as ship’s propellers, but now most such applications use reduction gears or an intermediate electrical step, where the turbine is used to generate electricity which then powers an electric motor connected to the mechanical load.
Gas turbine engines are sometimes referred to as turbine engines. Such engines usually feature an inlet, fan, compressor, combustor and nozzle (possibly other assemblies) in addition to one or more turbines.
The gasflow in most turbines employed in gas turbine engines remains subsonic throughout the expansion process. In a transonic turbine the gasflow becomes supersonic as it exists the nozzle guide vanes. Transonic turbines operate at a higher pressure ratio than normal but are usually less efficient and uncommon. This turbine works well in creating power from water.
Multi-stage turbines have a set of static (meaning stationary) inlet guide vanes that direct the gasflow onto the rotating rotor blades. In a statorless turbine the gasflow existing in an upstream rotor impinges onto a downstream rotor without an intermediate set of stator vanes that rearrange the pressure / velocity energy levels of the flow.
Conventional high-pressure turbine blades (and vanes) are made of nickel-steel alloys and often utilize internal aircooling passages to prevent the metal from melting. In recent years experimental ceramic blades have been manufactured and tested in gas turbines with a view of increasing rotor inlet temperatures and, possibly, eliminating aircooling. Ceramic blades are more brittle than their metallic counterparts and carry a greater risk of catastrophic blade failure. Many turbine rotor blades have a shroud at the top to increase damping and thereby reduce blade flutter. This turbines are called shrouded turbines. Modern practice is, where possible, to eliminate the rotor shroud reducing the centrifugal load on the blade and the cooling requirements. Such turbines are called shroudless turbines. Bladeless turbine uses the boundary layer effect, and not a fluid impinging upon the blades as in a conventional turbine.
Turbines are often a part of a larger machine. A gas turbine, for example, may refer to an internal combustion machine that contains a turbine, ducts, compressor, combustor, heat-exchanger, fan and (in the case of one designed to produce electricity) an alternator. However, it must be noted that the collective machine referred to as the turbine is designed to transfer energy from a fuel to the fluid passing through the internal combustion device as a means of propulsion. Reciprocating piston engines such as aircraft engines can use a turbine powered by their exhaust to drive an intake-air compressor.
Turbines can have incredible power density with respect to volume and weight. This is because of their ability to operate at very high speeds. The Space Shuttle’s main engines use turbopumps (machines consisting of a pump driven by a turbine engine) to feed the propellants (liquid oxygen and liquid hydrogen) into the engine combustion chamber. The liquid hydrogen turbopump is slightly larger than an automobile engine (weighing approximately 700 lb) and produces nearly 70,000 hp (52,2 MW).
Turboexpanders are widely used as sources of refrigeration in industrial processes.
1with a view of - з метою
Exercise 7. Translate the following international words. Mind the difference in their pronunciation and meanings in English and Ukrainian.
Reverse, compressor, gas, energy, turbine, potential, kinetic, physical, rotor, concept, form, type, effect, designer, base, style, electricity, thermal, mechanical, propeller, motor, normal, static, stator, metal, experimental, ceramic, test, risk, effect, thermodynamic, control.
Exercise 8. Determine the parts of speech of the following words, define their prefixes and suffixes, where possible, and translate them.
Windmill, incompressible, compressor, pressure, casement, runner, reaction, slower, generation, directly, propellant, electrical, subsonic, transonic, gasflow, supersonic, higher, less, multi-stage, fluid-flow, upstream, downstream, intermediate, stator, statorless, high-pressure, nickel-steel, greater, counterpart, failure, bladeless, normally, efficiency, larger, heat-exchanger, alternator, collective, provision, incredible, density, turbopump, propellant, combustor, combustion, rearrange, uncommon, propeller, slightly, larger, simplest, assembly, rotor, layer, rotation.
Exercise 9. Combine the words of two groups to make all possible “noun+noun” word combinations. Translate them.
Group I: fluid, rotor, water, gas, steam, impulse, reaction, stator, pressure, velocity, wind, rotation, power, inlet.
Group II: assembly, turbine, flow, energy, blade, head, casement, medium, duct, speed, plant, engine, ratio, vane, temperature.
Exercise 10. Translate and comment upon the following grammar forms.
Moving, operating, working, employed, diminished, attached, changed, accelerating, prepared, reaching, needed, immersed, casing, used, expanding, deflecting, blading, operating, using, connected, referred, employed, existing, cooling, being, encountered, melting, manufactured, tested, damping, reducing, impinging, produced, reducing, passing, powered, driven, made, weighing, needed.
Exercise 11. Match the synonymous words and word combinations.
| 1) velocity 2) use 3) power 4) thrust 5) rotor 6) impulse 7) propulsion 8) vane 9) produce 10) diminish 11) work 12) combustion chamber 13) supply 14) fuel | a) runner b) draft c) forward movement d) feed e) speed f) energy g) propellant h) manufacture i) employ j) blade k) combustor l) operation m) stimulus n) reduce |
Exercise 12. Translate the words used both as verbs and nouns.
Power, design, work, cool, pass, extract, thrust, draft, flow, move, pump, water, control, change, spin, reverse, transfer, tube, use, effect, speed, fuel, load, test, manufacture, increase, heat, guide, exit, focus.
Exercise 13. Complete the sentences putting the verbs in brackets in the correct form. Translate them.
1. The simplest turbines have one (to move) part, a rotor assembly, which is a shaft with blades (to attach). 2. A (to work) fluid contains potential energy and kinetic energy. 3. The (to result) impulse spins the turbine and leaves the fluid flow with (to diminish) kinetic energy. 4. Reaction turbines develop torque by (to react) to the fluid pressure or weight. 4. Wind turbines also gain some energy from the impulse of the wind by (to deflect) it at an angle. 5. At low pressure the (to operate) fluid medium expands in volume for small changes in pressure. 6. Steam turbines are (to use) for the generation of electricity in thermal power plants such as plants (to use) coal, fuel oil or nuclear power. 7. Gas turbine engines are sometimes (to refer) to as turbine engines. 8. Multi-stage turbines have a set of static inlet guide vanes that direct the gasflow onto the (to rotate) rotor blades. 9. In recent years experimental ceramic blades have been (to manufacture) and (to test) in gas turbines with a view to (to increase) rotor inlet temperatures and (to eliminate) air (to cool). 10. Many turbine rotor blades have a shroud at the top to increase (to damp). 11. Modern practice is to eliminate the rotor shroud (to reduce) the centrifugal load on the blade and the (to cool) requirements. 12. Bladeless turbine uses the boundary layer effect, and not a fluid (to impinge) upon the blades as in a conventional turbine. 13. Most jet engines rely on turbines to supply mechanical work from their (to work) fluid and fuel all nuclear ships and power plants. 14. The collective machine (to refer) to as the turbine is (to design) to transfer energy from a fuel to the fluid (to pass) through the internal combustion device.
Exercise 14. Translate the following terminological word combinations.
Rotary engine, extract energy, fluid flow, rotor assembly, impart energy to the rotor, focus and control the fluid, fluid-flow conditions, operate in reverse, collect energy, high velocity fluid jet, turbine rotor blade, transfer of energy, working fluid, harness the expanding gas efficiently, use for the generation of electricity, thermal power plant, drive mechanical device, compressor inlet, guide vane, direct gasflow, rotating rotor blades, impinge onto a downstream rotor, intermediate set of stator vanes, utilize internal aircooling passages, reduce blade flutter, shrouded turbine, shroudless turbine, supply mechanical work, waste heat, collective machine, combustion device, reciprocating piston engine, powered by the exhaust, drive an intake-air compressor, power density, with respect to volume and weight, operate at very high speeds, use turbopump, feed the propellant, thermal power plant, industrial, turboexpander, source of refrigeration, thermodynamic cycle.
Exercise 15. Complete the sentences with English equivalents of the terms in brackets.
1. A turbine is a (роторний двигун) that (видаляє енергію) from a (рідинний потік). 2. Gas, steam and water turbines usually have a (кожух) around the (лопатки) that focuses and controls the fluid. 3. A (робоча рідина) contains (потенціальна енергія) and (кінетична енергія). 4. (Активна турбіна) changes the direction of (високошвидкісний рідинний струмінь). 5. (Реактивні турбіни) develop (обертаючий момент) by reacting to the fluid pressure or weight. 6. The pressure of the fluid changes as it passes through the (лопатки ротора турбіни). 7. (Парові турбіни) are used for the generation of electricity in (теплові електростанції) such as plants using coal, fuel oil or nuclear power. 8. (Газотурбінні двигуни) are sometimes referred to as turbine engines, featuring an (вхідний отвір, вентилятор, камера згорання і форсунка) in addition to one or more engines. 9. (Багатоступеневі турбіни) have a set of static (направляючі лопатки вхідного отвору) that direct the gasflow onto the rotating (лопатки робочого колеса). 10. In a statorless turbine the gasflow existing in (ротор, що знаходиться вище / попереду за течією) impinges onto a (ротор, що знаходиться нижче / далі / позаду за течією). 11. Conventional (лопатки турбіни високого тиску) are made of nickel-steel alloys. 12. (Бандажовані турбіни) have a (бандаж) at the top of rotor blades. 13. In (небандажовані турбіни) the rotor shroud is eliminated reducing the (відцентрове навантаження) on the blade and the cooling requirements. 14. A gas turbine may refer to (двигунів внутрішнього згорання).
Exercise 16. Give definitions to the following terms.
Turbine, compressor or pump, impulse turbine, reaction turbine, steam turbine, gas turbine engine, transonic turbine, multi-stage turbine, statorless turbine, shrouded turbine, shroudless turbine, bladeless turbine, wind turbine, collective machine, turbopump, turboexpander.
Exercise 17. Match the definitions in the left column with the terms in the right column.
| 1. A rotary engine that extracts energy from a fluid flow - | a) reaction turbine |
| 2. A device similar to a turbine but operating in reverse - | b) gas turbine engines |
| 3. A turbine which changes the direction of flow of a high velocity fluid jet - | c) turbine |
| 4. A turbine which develops torque by reacting to the fluid pressure or weight - | d) compressor or pump |
| 5. Turbines used for generation of electricity in thermal power plants - | e) impulse turbine |
| 6. Turbines referred to as turbine engines featuring an inlet, fan, compressor, combustor, nozzle and other assemblies in addition to one or more turbines - | f) statorless turbine |
| 7. Turbines with a set of static inlet guide vanes - | g) shroudless turbines |
| 8. A turbine operating without an intermediate set of stator vanes - | h) steam turbines |
| 9. Turbines with rotor blades, having a shroud at the top - | i) bladeless turbine |
| 10. Turbines having no rotor shrouds - | j) shrouded turbine |
| 11. A turbine using the boundary layer effect and not a fluid as in a conventional turbine - | k) multi-stage turbine |
| 12. A turbine designed to transfer energy from a fuel to the fluid passing through the internal combustion device as means of propulsion - | l) collective machine |
Exercise 18. Answer the questions on texts 1, 2.
1. What is a turbine? 2. What do simplest turbines consist of? 3. What are the early turbine examples? 4. What turbines are called impulse turbines? 5. How do impulse turbines operate? 6. What turbines are called reaction turbines? 7. What is the main difference between impulse and reaction turbines? 8. How are concepts described in Newton’s second and third laws used in turbine designs? 9. Where are steam turbines used? 10. What may gas turbine engines be referred to as? 11. What turbines, usually less efficient and uncommon, are used for creating power from water? 12. What turbines are called multi-stage turbines? 13. How does a statorless turbines operate? 14. How may conventional high-pressure turbine blades be prevented from metal melting? 15. What kind of blades were manufactured and tested in gas turbines with a view to increase rotor inlet temperatures and possibly eliminate aircooling? 16. What is the main difference between shrouded and shroudless turibines? 17. What is the principle of operation of a bladeless turbine? 18. Why is a gas turbine referred to an internal combustion machine? 19. What is collective machine designed for? 20. What turbines are used in reciprocating piston engines?
Exercise 19. Speak on:
1. Types of turbines.
2. Turbines operation and purposes.
Exercise 20. Memorize the following words and word combinations to text 3.
Recuperator – рекуператор (що відновлює, генерує)
foil – амальгама, фольга, пластина
foil bearing – пластинковий підшипник
bearing – підшипник
radial – радіальний; відцентровий
couple – сполучатися; пара сил (у механіці)
close-coupled – щільно з’єднані
release – вивільняти(ся)
isentropically – ізентропічно
ignite – займатися, запалюватися
constant – постійний
withstand – протистояти
recover – відновлювати; регенерувати; видаляти; утилізувати
waste – відпрацьований; марно витрачати
prior – до
considerably – значно
sophisticated – ускладнений
vast – величезний
piping – трубопровід
produce – створювати
determine – визначати
gain – отримувати
independent of – незалежно від
rpm–revolutions per minute – число обертів за хвилину
journal bearing – опорний підшипник, радіальний підшипник
thrust bearing – упорний підшипник, підп’ятник
critical – важливий
ball bearing – кульковий підшипник
jet engine – реактивний двигун
ducted fan – тяговий вентилятор
turbojets – турбореактивні двигуни
turbofans – турбовентиляторні двигуни
auxiliary – допоміжний, додатковий
Exercise 21. Read, translate and give the gist of text 3.