Навчальний посібник з англійської мови за професійним спрямуванням "Professional English. Aircraft Design and Maintenance"




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S. Why does this type of engine utilize the double-sided impeller?

T. Because using this type of impeller we reduce the overall (загальний / общий) diameter of the engine. The rotor is mounted by means of two bearings. There are ball bearings and roller bearings. The roller bearing is “роликовий підшипник / роликовый подшипник”. Can you translate the meaning of the expression "the ball bearing"?

S. "кульковий підшипник/шариковый подшипник".

Т. Right you are. And now look at this picture (Fig.II.2.3.) This picture shows the centrifugal compressor too. The ball bearing is mounted on the front shaft. The roller bearing supports the rear stub shaft. What type of compressor is illustrated in Fig.II.2.3?

S. It is a centrifugal type compressor.

Fig.II.2.3





Exercise 17. Read, translate and give the gist of text 3.
Text 3. Centrifugal Compressor

The centrifugal compressor is sometimes referred to as radial outflow compressor. It receives the air at its centre at a relatively low velocity and accelerates it outward by centrifugal force up to more high velocity. As the result the air is increased in both velocity and pressure.

The centrifugal compressor consists of an impeller rotor, a diffuser, and a manifold. The impeller can be either single- or double-sided. The diffuser acts as a divergent duct to slow down and increase static pressure. The compressor manifold distributes the air in a smooth flow into the compressor section. The most generally used centrifugal compressor is the single-sided type with one stage.

A centrifugal compressor may be used in combination with an axial flow compressor but all of the larger engines today use axial-flow compressors.

The rotor is mounted by means of two bearings: a ball bearing and a roller bearing. The ball bearing is mounted on the front shaft. The roller bearing supports the rear stub shaft.

Some engines use a single-sided or single-entry impeller, others use a double-sided or double-entry impeller. Most gas-turbine engines of the centrifugal type utilize the double-sided impeller as it reduces the overall diameter of the engine.

The multistage centrifugal compressors consist of two or more single-entry compressors mounted on the same shaft.

The air compressed by the first stage is passed on to the second stage. This stage further compresses the air before passing it on to still another stage if there is one1.



Note:

1. if there is one- якщо така існує / если такая имеется.


Exercise 18. Answer the questions on text 3.

1. What does the centrifugal compressor consist of? 2. What impeller does the centrifugal compressor utilize? 3. What acts as a divergent duct? 4. What does the compressor manifold do? 5. What type of compressor do all of larger engines use? 6. Where is the ball bearing mounted? 7. What bearing supports the rear stub shaft? 8. Why do most gas turbines of the centrifugal type utilize the double-sided impeller? 9. What does the multi-stage centrifugal compressor consist of?


Exercise 19. Translate the verb-noun pairs.

To operate – operation, to compress – compression, to enter – entry (entrance), to utilize – utilization, to reduce – reduction, to rotate – rotation, to roll – roller, to impell – impeller, to pass – passage, to develop – development, to propel – propeller, to lose – loss, to convert – conversion, to act – action, to move – motion (movement).


Exercise 20. Translate the words with prefix multi-.

Multispar, multibladed, multiengined, multinozzle, multimode, multiplace, multistaged, multicomponent, multisection, multirotor, multi-position, multichambered, multislotted, multidimentional, multispeed, multipurpose, multiwheel.


Exercise 21. Translate “noun + noun” collocations.

Engine design, engine operation, piston engine, air flow, ball bearing, stator blades, compressor casing, compressor rotor, pressure ratio, fuel consumption, compressor stage, air speed, temperature rise, compressor manifold, combustion chamber, air intake, gas turbine, fuel-air mixture.


Exercise 22. Fill in the blanks with the following terms: the overall diameter; a diffuser, and a manifold; bearings; the double-sided; ball; the first stage; the roller bearing; the single-sided.

1.The centrifugal compressor consists of the impeller rotor, … ... . 2. The rotor is mounted by means of two ... . 3. The double-sided impeller reduces ... ... of the engine. 4. ... ... supports the rear stub shaft. 5. The ... bearing is mounted on the front stub shaft. 6. Most gas-turbine engines of the centrifugal type utilize ... ... impeller. 7. The impeller can be either ... or double-sided. 8. The air compressed by … … is passed on to the second stage.


Exercise 23. Make questions to the sentence.

The impeller of a centrifugal compressor is usually constructed of a heat-treated aluminum alloy forging.

1. Is ....................? 2. What is ...........? 3. What impeller ............?

4. What ............of ? 5. What alloy .........of ?


Exercise 24. Translate the sentences.

1. Axial flow compressor is a type of compressor used in a gas turbine engine in which air passes through the compressor in a straight flow from front to rear. 2. Centrifugal flow compressor is a type of compressor in which air is taken into the centre of the impeller and is pushed outward axially into a diffuser where it is fastened and pressure is decreased. 3. A rotating part of an engine, driven by the low pressure turbine, for air supply to the engine and to the duct around the front part of the engine is a fan. 4. The fan provides the major portion of engine thrust. 5. Compressor pressure ratio is the ratio of inlet pressure to exhaust pressure measurements. 6. The compression ratio is used as the primary parameter to set thrust on some engines.


Exercise 25. Translate into English.

1. Компресор забезпечує необхі-дний ступінь стискання.

1. Компрессор обеспечивает необходимую степень сжатия.

2. Одновхідний компресор трохи більш ефективний, ніж двовхідний.

2. Одновходной компрессор немного более эффективен, чем двувходной.

3. Ротор компресора монтується на двох підшипниках.

3. Ротор компрессора монти-руется на двух подшипниках.

4. Кульковий підшипник закріп-люється на передньому кореневому валі.

4. Шариковый подшипник кре-пится на переднем корневом валу.

5. Роликовий підшипник підтримує задній кореневий вал

5. Роликовый подшипник поддерживает задний корневой вал.

6. Напрямні лопатки збираються разом з крильчаткою.

6. Направляющие лопатки соби-раются вместе с крыльчаткой.

7. У більшості газотурбінних двигунів з відцентровим компресором використовується двостороння крильчатка.

7. У большинства газотурбинных двигателей с центробежным компрессором используется двусторонняя крыльчатка.

8. Двостороння крильчатка зменшує загальний діаметр двигуна.

8. Двусторонняя крыльчатка уменьшает общий диаметр дви-гателя.


Exercise 26. Translate text 4 in a written form and entitle it.
Text 4

The centrifugal compressor operates by taking in the outside air and rotating it by means of the impeller. The impeller of the centrifugal compressor is usually constructed of a heat-treated aluminum alloy forging. The stator of the centrifugal compres­sor is constructed of a heat-treated aluminum alloy casting. The impeller is assembled together with the guide vanes and the two stub shafts. The two stub shafts provide the bearing support for mounting the impeller in the engine. In the case of the centrifugal compressor, some engines use the single-sided or single-entry compressor. This type is a little more efficient than the double-sided type but its use requires a larger diameter for the same result.

The efficiency of the single-stage centrifugal compressor is relatively low. It is capable of building up the pressure four or five times which is known as the pressure ratio of 4 or 5 to 1.
Exercise 27. Find in text 4 eight words that can be used both as a noun and a verb. Give their translation.
Exercise 28. Give English equivalents.

Жаростійкий сплав / жаропрочный сплав; кореневий вал / корневой вал; підшипникова опора / подшипниковая опора; більш ефективний / более эффективный; відносно низька вартість / относительно низкая стоимость; більший діаметр / больший диаметр; виготовлятися зі сплаву / изготавливаться из сплава; підвищувати тиск в 5 разів / повышать давление в 5 раз; збиратися разом / собираться вместе; термічно оброблений / термически обработанный.


Exercise 29. Memorize the active vocabulary.

bladed disk

диск з лопатками

диск с лопатками

coaxial

коаксіальний, зі спільною віссю

коаксиальный, соосный

stationary

1. постійний 2.стаціонарний; нерухомий

1. постоянный 2. стационарный; неподвижный

casing

кожух, корпус

кожух, корпус

half cylinder

напівциліндр

полуцилиндр

obtain

отримувати

получать

redirect

переспрямовувати

перенаправлять

rim

1. обід;бандаж (колеса) 2. край; кромка

1. обод; бандаж (колеса) 2. край; кромка

shrink (shrank, shrunk)

насаджувати (на вал) в гарячому стані

насаживать (на вал)

в горячем состоянии



shroud

бандажний обід

бандажный обод

in series

послідовно, в ряд

последовательно, в ряд



Exercise 30. Practise out the dialogue.
Dialogue

T. Let's proceed with our theme. We’ll consider the two main parts of a compressor: the rotor and the stator. What does the centrifugal compressor consist of?

S. It consists of the impeller, guide vanes and two stub shafts.

T. That's correct. The rotor of the axial-flow compressor consists of several bladed disks. The words “blade” and “vane” (лопатка / лопатка) are synonyms. The word combination “bladed disk” means “диск з лопатками / диск с лопатками”. These bladed disks are shrunk (насаджувати в нагрітому стані / насаживать в нагретом состоянии) on a shaft. The verb “to shrink” is irregular and its forms are: shrink-shrank-shrunk. Each row of blades constitutes a stage. The number of stages in the axial compressor varies with the engine design. Look at the picture (Fig. II.2.4.)

Fig. II.2.4.
It shows the assembly of an axial-flow compressor. How many stages are there in this compressor?
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