An axial compressor is a famous type of centrifugal compressor. In an axial compressor, air flows parallel to the axis of rotation. The several blades of impellers are part of the compressor. The impeller blade attaches to the central shaft and rotates at high speed. The axial compressor has some fixed and static vanes that are called a stator.
The task of the stator is to increase the pressure and prevent the water flow from rotating around the axis by returning the current in a direction parallel to the axis. The stator of this compressor is connected to the chamber. This is the animated version of the axial compressor:
Axial Compressor Working
The axial compressor is a dynamic compressor. Unlike positive displacement compressors, dynamic compressors operate at constant pressure and are subject to changes in external conditions such as the inlet temperature.
As the name suggests, the axial compressor has an axial flow of fluid. The air or gas flows along the compressor shaft through rows of rotating and stationary blades. The blade converts the moving force into pressure, and an internal balancing drum is used to compensate for the axial thrust. These compressors are generally smaller and lighter than radial centrifugal compressors but run faster.
Like other dynamic compressors, axial compressors use continuous high-volume flows at medium pressures, such as ventilation systems. Axial compressors work well when manufactured with gas turbines to generate power and aircraft ratios due to their high rotational speed.
Whether it’s a scroll compressor or a dynamic compressor, the result is always compressed air. However, even though all air compressors produce the same final product, but they have different designs.
Components of an Axial Flow Compressor
The following components are main in a typical axial-flow compressor:
- Rotor Blades
- Stator Blades
The axial compressor has a rotating part called the rotor. A rotating drum is part of the rotor. A rotor drum attaches to the shaft. The real rotating element is a shaft. The circular motion is transmitted to the drum by the shaft. The installation hardware for the rotor blades is located on the rotor drum.
The blades install on the rotor drum. The responsibility for increasing the thrust is on the rotor blades because they rotate.
This cover forms the outer protective film of the axial compressor. A casing performs various functions.
In the casing, stator blades are mounted. These vanes are fixed with axial compressors.
Unlike the rotor blades, which rotate with the rotor drum, the stator blades remain constant during all compression stages.
The function of the axial compressor stator blades includes the following:
- As it serves as driving vanes.
- They direct the gas in a certain direction inside the compressor. With the correct contact angle, the gas strikes the rotor blade by the stator.
- The responsibility for increasing the gas pressure is of the stator.
Advantages of Axial Compressor
- Compared to other types of compressors, the axial compressor has a very high maximum efficiency.
- Flow Mass flow is very high.
- High pressure and high-efficiency ratio. A good pressure ratio is also achieved by increasing the number of steps. Even with an axial compressor, it is possible to achieve a pressure ratio of 40:1.
- The aerodynamic traction is reduced because the forehead area of a given flow is small.
Disadvantages of Axial Compressor
- Building an axial compressor is difficult.
- A very expensive machine.
- The installation of this device is cumbersome and difficult.
- Required a very high power to start the axial compressor or start the compression process.
- The pressure rise is very low in all phases. The different steps for axial compressors are used for this reason.
The loses in an axial compressor.
Axial compressors, like any other machine tool, are no exception. This compressor faces the following types of leaks as usual.
- The configuration file is not available.
- Loss of skin friction or loss of rings.
- loss of secondary flow loss
- Tip’s leakages loss
1) The configuration file is not available
This loss is caused by the growth of the edges and the subsequent separation of the leaf characteristics. In other words, this loss is due to the nature of its wing structure.
2) Skin friction or ring loss
This is the loss of viscosity due to the axial widening of the boundary layer. This represents about 50% of the total loss.
3) Secondary Current Loss
Secondary current occurs when current flows through the blades of the blade curve. The loss caused by this secondary flow is called secondary loss.
4) Tip Leakage loss
Due to the distance between the chamber and the blade, there will be flow from the pressure level to the suction surface and will cause mechanical losses.
Applications of Axial Compressors
- Purification (FCC / RCC Catalyst Reconstruction Air)
- Steel (blast furnace air)
- Nitric acid
- High air separation capacity
- Wastewater Treatment
- Industrial wind (high wind tunnel and laboratory)
- Compressed Air Energy Storage (CAES)
- Dehydration Propane