Combustion chamber GE J79
Flame fronts generally travel _____ just Mach 0.05, whereas air flows _____ jet engines are considerably faster than this. Combustors typically employ structures to give a sheltered (закрытая) combustion zone called a flame holder. Combustor configurations include can, annular, and can-annular. Great care must be taken to keep the flame burning _____ a moderately fast moving airstream, at all throttle conditions, as efficiently as possible. Since the turbine cannot withstand stoichiometric temperatures (a mixture ratio of around 15:1), some _____ the compressor air is used to quench the exit temperature of the combustor to an acceptable level (an overall mixture ratio _____ between 45:1 and 130:1 is used). Air used _____ combustion is considered to be primary airflow, while excess air used _____ cooling is called secondary airflow. The secondary airflow is ported _____many small holes _____ the burner cans to create a blanket _____ cooler air to insulate the metal surfaces of the combustion can _____ the flame. If the metal were subjected _____ the direct flame for any length of time, it would eventually burn through.
V. a) Collocate words in the table.
b) Make up sentences with these word combinations in written. VI. Fill in the gaps using the words from the oval. Mind, there is one extra word! Translate the text into Russian in written.
A firing chamber is the chamber of a rocket engine in which the fuel and the oxidizer burn to produce high pressure gas expelled from the engine _____ to provide thrust. To begin with, the fuel and oxidizer pass (separate) through a complex _____ in which each component is broken down into smaller and smaller flow _____, in the same way that arteries in the body divide into increasingly small capillaries. Then the propellants are injected into the combustion chamber via the _____ – a plate at the top of the chamber which takes the small flow streams and forces them through an _____. The purpose of the injector is to mix the fuel and oxidizer molecules as thoroughly and evenly as possible. Once mixed, the fuel and oxidizer are ignited by the intense heat inside the chamber. To start the combustion, an ignition source (such as an electric _____) may be needed. Alternatively, some propellants are hypergolic – they spontaneously combust on contact – and do not need an ignition source.
VII. Translate the following sentences. Pay special attention to the words. in bold. Give your own explanation of them. Incomplete combustion (a state in which not all the fuel in the combustion chamber burns) may result from inadequate chamber design, or it may be deliberately designed into the system so that the unburned fuel acts as a chamber coolant. Generally, incomplete combustion is indicative of a system not functioning efficiently. Combustion chamber is a space over, or in front of, a boiler furnace where the gases from the fire become more thoroughly mixed and burnt. The clearance space in the cylinder of an internal combustion engine is compressed and ignited. Speaking Work in pairs and make a dialogue discussing the operation of the combustion chamber on the following points: - introducing of fuel - air circulation - mixing the fuel and the air - ignition - resultant gases - protection from high temperature of combustion
Writing Summarize the information given in the text “Operation of the combustion chamber”. Use the key-patterns. Unit V
Before you Begin
I. Read the text and render its idea in Russian. Try to guess what the term “Inlet Ducts” means.
Pilot intakes are the dominant type for subsonic applications. A subsonic pilot inlet is little more than a tube with an aerodynamic fairing (обтекатель) around it. At zero airspeed, air approaches the intake from a multitude of directions: from directly ahead, radially, or even from behind the plane of the intake lip. At low airspeeds, the stream tube approaching the lip is larger in cross-section than the lip flow area, whereas at the intake design flight Mach number the two flow areas are equal. At high flight speeds the stream tube is smaller, with excess air spilling (распыление) over the lip. Beginning around Mach 0.85, shock waves can occur as the air accelerates through the intake throat. Careful radiusing of the lip region is required to optimize intake pressure recovery (and distortion) throughout the flight envelope.
II. Scan the text to find the definition of inlet ducts. Check if your predictions were correct.
Reading I. In the text, find definitions of: - the duct pressure efficiency ratio - the ram recovery point - a bellmouth inlet
II. Skim the text and try to explain the meaning of the words in bold from the content of the text.
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Use the following phrases:
Inlet Ducts
