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A turboprop engine
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1. inlet assembly
2. compressor
3. combustion chamber
4. gas turbine
5. exhaust unit
6. propeller
| a rocket engine 1. oxygen 2. liquid fuel 3. combustion chamber 4. propelling nozzle 5. fuel injectors |
| a ram jet engine |
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Exercise 33. Read the dialogue. What new information have you got?
Instructor: Today we are going to discuss aviation jet engines, which are actually turbo-jet engines, having a compressor at the front to force the air in.
Peter: What drives the compressor?
Instructor: There's plenty of energy at the back, where the hot gases leave the combustion chamber. If you put a turbine there and connect it to the compressor by a shaft, that would solve the problem, wouldn’t’ it?
Nick: What's about the other types of jet engines?
Instructor: They're all variations on the turbo-jet principle. There's the turbo-prop, for example, where the turbines rotate both the
compressor and an ordinary propeller.
Nick: What are the advantages of this type of engine?
Instructor: At very low flying speeds propellers are more efficient form of propulsion that jet engines. Pure jet engines are very efficient at high subsonic speeds, but at medium and low subsonic speeds their efficiency sharply decreases.
Peter: And this was the reason for development of by-pass engines.
Instructor: Right you are, this was the reason. But the development of bypass engines was only the first step.
Nick: Are by-pass engines still used?
Instructor: They are, but in a modified form. In a by-pass engine only some of the air goes straight through; the remainder if passed through ducts, round the combustion chamber and turbine, but later rejoins the main stream at the rear.
Peter: And what was the second step?
Instructor: The second step was development of fan engines. The first set of rotor blades of the axial compressor was enlarged to form a sort of multi-blade propeller, known as the fan.
Nick: Modern jet engines look so big and impressive. Is it because of their large diameter fans?
Instructor: The diameter of modem high by-pass-ratio jet engines is up to three meters, and they are pylon-mounted.
Exercise 34. Make up your own dialogues.
€ Exercise 35. Do the two-way translation.
| 1. От чего зависит количество двигателей и их расположение на самолетах? 2. Где на самолете могут располагаться двигатели? 3. На какие классы подразделяются реактивные двигатели? 4. Какие два основных типа ракетных двигателей существуют? 5. Какой самый простой из воздушно-реактивных двигателей? 6. Для чего предназначен пульсирующий двигатель? 7. Какие двигатели относятся к газотурбинным двигателям? 8. Из чего состоит газотурбинный двигатель? 9. Как подразделяются турбореактивные двигатели? 10. На каких самолетах используются турбовентиляторные двигатели? | 1. Types of engines, their number and location on the airplane depend on the airplane performances 2. Engines may be mounted on the wings, on the fuselage (forward or aft) or under the wings on pylons. 3. Jet engines fall into two main classes: air-breathing engines and rocket engines. 4. There are two basic types of rocket engines: liquid-propellant and solid-propellant rocket engines. 5. The simplest type of air-breathing engine is the ramjet engine. 6. Possible application of the pulsejet is to propel pilotless military weapons. 7. Turbojet, turboprop and turbofan belong to the family of gas-turbine engines. 8. It comprises the inlet assembly (diffuser), the compressor, the combustion chamber, the gas turbine and exhaust nozzle. 9. The turbojets are classified into 2 groups according to the kind of compressors which they use. 10. Turbofans are widely used in aviation, especially in large multi-engine aircraft |
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