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The gas turbine engine consists of a rotary air compressor with an air intake, one or more combustion chambers, a turbine and an exhaust outlet.
There are two basic types of rotary air compressors: a centrifugal flow compressor and an axial flow one.
The centrifugal flow compressor is a single or two-stage unit which has an impelle r to accelerate the air and a diffuser to produce the required pressure rise. The axial flow compressor is a multi-stage unit with alternate rows of rotating and stationary blades to accelerate and diffuse the air until the required pressure rise is obtained.
The combustion chamber has the difficult task that is to expand the air passing through the engine by burning fuel in the air stream. Although all combustion chambers work on the same principles, they may be installed in the engine in some different ways. The multiple combustion chamber layout is often used with engines having centrifugal compressors. Annular combustion chambers are used with engines having axial compressors.
The turbine provides the power to drive the compressor and accessories. It extracts energy from the hot gases released from the combustion system and expands them to a lower pressure and temperature. The turbine may consist of several stages, each using one row of stationary guide vanes and row of moving blades.
The exhaust system passes the turbine discharge gases to atmosphere at a velocity, and in the required direction, to provide the resultant thrust.
Задание 8. Исправьте утверждения, если они не соответствуют действительности, используя следующие фразы: I agree (don’t agree). I think you are mistaken. That’s right (wrong).
1. The axial flow compressor is a single-stage unit with alternate rows of rotating and stationary blades.
2. There are many different types of rotary air compressors.
3. The multiple combustion chamber layout is often used with engines having centrifugal compressors.
4. The turbine provides the power to drive the impeller and accessories.
5. The turbine consists of one stage of stationary guide vanes and moving blades.
6. The exhaust system passes the turbine discharge gases to atmosphere to provide the resultant thrust.
Задание 9. Прочтите и переведите предложения.
1. The centrifugal-type compressor produces a high-pressure rise n a single stage.
2. Most gas turbines of the centrifugal type use the double-sided impeller to reduce the diameter of the engine.
3. The number of stages in an axial compressor depends on the engine design.
4. The function of the diffuser assembly is to direct air from the compressor to the combustion chamber and to change air pressure and velocity.
5. In general, an annular combustion chamber is a single chamber completely surrounding the engine.
Задание 10. Переведите следующие вопросы на английский язык и ответьте на них.
1. Из каких компонентов состоит газотурбинный двигатель?
2. Сколько основных типов роторного компрессора вы знаете?
3. Какова функция диффузора?
4. Какие типы лопаток у осевого компрессора?
5. Где сжигается топливо?
6. В каких двигателях часто используется трубчатая конструкция камеры сгорания?
7. Как турбина создает мощность для того, чтобы приводить в движение компрессор и вспомогательные агрегаты двигателя?
8. Из каких ступеней (каскадов) может состоять турбина?
9. Какова функция выхлопного устройства?
Задание 11. Прочтите и письменно переведите текст без словаря.
The gas turbine engine takes air from the atmosphere and, after compressing and heating, it uses some of its energy to drive the turbine that powers the compressor. The mechanical arrangement of the gas turbine engine is simple. It consists of two main rotating parts, a compressor and turbine, and one or a number of combustion chambers. The turbojet engine is most suitable for high forward speeds. At aircraft speeds below 450 miles per hour the jet engine is less efficient than a propeller-type engine. The development of high-speed propellers and propfan engines provides further improvement in the propulsive efficiency of modern aircraft engines. At its normal cruising speed, for example, the propfan engines provide between 75 and 85 per cent propulsive efficiency.
Notes:
a) high-speed propeller – высокооборотный воздушный винт
b) propfan engine – винтовентиляторный двигатель (тяга такого двигателя создается в основном за счет воздушного винта)
c) propulsive efficiency – тяговый КПД двигателя, характеризующий его способность преобразовывать тепловую энергию топлива в тягу
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