The turboprop engine

1. The engine consists of a diffuser, a mechanical compressor, a combustion chamber, a turbine, an exhaust nozzle, a reduction gear, and a propeller. The diffuser mechanical compressor and combustion chamber function in the same manner as in the turbojet engine. However, in the turboprop engine the turbine extracts much more power than it doеs in the turbojet engine, because the turbine provides power for both the compressor and the propeller. When all of this energy is extracted from the high temperature gases, there is little energy left for producing jet thrust. Thus, the turboprop engine derives most of its propulsive thrust from the propeller and derives only a small portion (10 to 25% depending on the flight velocity from the exhaust nozzle). Since the shaft rotation speed of gas turbine engines is very high (approximately 12,000 rpm), a reduction gear must be placed between the turbine shaft and the propeller to enable the propeller to operate efficiently.

2. The turboprop engine is essentially a gas turbine power plant because, as pointed out before, little power is derived from the exhaust nozzle: still, as flight speeds are increased, the ratio of nozzle power to propeller power for maximum thrust tends to become higher. The propulsive thrust is provided by a momentum change of the air. First, the propeller increases the air momentum, and second, the overall engine, from diffuser to nozzle, provides an internal momentum increase. The sum of these two thrusts is the total thrust developed by the engine.

II. Найдите в тексте ответы на следующие вопросы:

1. What does the turboprop engine consist of?

2. What is the turboprop engine?

III. Выпишите из текста английские соответствия следующим сочетаниям:

1. как было указано выше

2. газотурбинный двигатель

3. выхлопное сопло

4. силовая установка газотурбинного двигателя

IV. Перепишите и переведите на русский язык следующие предло­жения. Обратите внимание на глаголы «should» (в значении «должен», «следует») и «would» (в сослагательном наклонении – глагол + частица «бы»):

1. The starting of a jet engine should always be carried out in accordance with the manufacturer’s operating instructions.

2. The filler plug (пробка заливного отверстия) should be loosened carefully with a wrench to allow the air to escape.

3. This engine would be more efficient.

4. The plane would cover the distance from Moscow to Khabarovsk during six hours non-stop flight.

V. Перепишите и переведите на русский язык следующие предложения. Обратите внимание на конструкцию "самостоятельный причастный оборот" (см. модель):

1. The problem of aeronautics being very important, Mendeleyev paid much attention to it.

2. Combustion chambers are joined by cross-ignition tubes, their purpose being to spread combustion from one chamber to the next.

3. An airplane engine operates in air of variable density and temperature, these characteristics being determined principally by the altitude of the operation.

4. The engine being simple, it is cheap to produce.

VI. Перепишите и переведите на русский язык следующие предложения. Обратите внимание на конструкцию "сложное дополнение" (см. модель):

1. We know the two-spool compressor to be most efficient.

2. We expect the new aircraft to fly this year.

3. The early artificial satellites showed the Earth to be surrounded by intense radiation.

4. Tests showed this type of combustor to be very efficient.

Date: 2016-05-25; view: 484; Нарушение авторских прав