Module 3 Flashcards
types of compressor
CENTRIFUGAL FLOW
AXIAL FLOW
(?) are dedicated components that sucks air (intake) from the atmosphere, compresses it in the combustion chamber to be used for combustion.
COMPRESSORS
The (?) is a single or two stage unit employing an impeller to accelerate the air and a diffuser to produce the required pressure rise.
CENTRIFUGAL FLOW COMPRESSOR
(?) have a single or double-sided impeller and occasionally a two-stage, single sided impeller is used, as on the Rolls-Royce Dart.
CENTRIFUGAL FLOW COMPRESSORS
The (?) rotates in ball and roller bearings and is either common
to the turbine shaft or split in the center and connected by a coupling, which is usually designed for ease of detachment.
Impeller Shaft
The (?) centers around the impeller, diffuser and air intake system.
construction of the compressor
The (?) consists of a forged disc with integral radially disposed vanes on one or both sides forming convergent passages in conjunction with the compressor casing.
IMPELLER
The clearance between the (?) is an important factor, as too small a clearance will set up aerodynamic buffeting impulses that could be transferred to the impeller and create an unsteady airflow and vibration.
impeller and the diffuser
The (?) is a multi-stage unit employing alternate rows of rotating (ROTOR) blades and stationary (STATOR) vanes.
AXIAL FLOW COMPRESSOR
rows of rotating blades
ROTOR
stationary vanes
STATOR
to accelerate and diffuse the air until the required pressure rise is obtained.
AXIAL FLOW COMPRESSOR
The (?) is a multi-stage unit as the amount of pressure increase by each stage is small.
COMPRESSOR
a stage consists of a row of rotating blades followed by a row of stator vanes.
COMPRESSOR
As the pressure ratio is (?) the incorporation of variable stator vanes ensures that the airflow is directed onto the succeeding stage of rotor blades at an acceptable angle.
increased
From the front to the rear of the compressor, from the low to the high
pressure end, there is a gradual reduction of the air (?) between the rotor shaft and the stator casing.
ANNULUS AREA
With regard to the advantages and disadvantages of the two types, (?)
the centrifugal compressor is usually more robust than the axial compressor and is also easier to develop and manufacture. The axial compressor however consumes far more air than a centrifugal compressor of the same frontal area and can be designed to attain much higher pressure ratios.
Since the air flow is an important factor in determining the amount of thrust, this means the axial compressor engine will also give (?).
more thrust for the same frontal area
This, plus the ability to increase the pressure ratio by (?), has led to the adoption of axial compressors in most engine designs.
addition of extra stages
