Axial Compressor Groove Purge System for Stall Suppression
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Solution Overview
Problem
The accumulation of a liquid membrane and impurities in the casing grooves of an axial compressor leads to reduced effectiveness in suppressing stall on rotor blades, especially when droplets are not sprayed during operation, causing high loads on blade cascades and potential stall issues.
Innovation Solution
Incorporating a purge system with communication holes inclined towards the downstream side that supplies high-pressure gas to the casing grooves to remove attachments such as liquid membranes and impurities, ensuring effective suppression of stall on rotor blades by maintaining groove cleanliness even when droplets are not introduced.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If droplets are introduced into the compressor to reduce compression work and improve efficiency, then the stage load on the front stage side is reduced and overall efficiency improves, but the groove accumulates liquid membrane and impurities which reduces its effectiveness in suppressing stall
Solution Approach 1:
The patent applies preliminary action by providing a purge system that actively removes liquid membrane and impurities from the groove before they can accumulate to harmful levels. The purge system includes purge holes through the casing and a purge air supply device that periodically or continuously blows purge air into the groove to prevent attachment accumulation, thereby maintaining the groove's stall suppression effectiveness while allowing droplet injection for efficiency improvement
Solution Approach 2:
The purge system utilizes the compressor's own compressed air as the purge air source, allowing the system to self-clean using its own operational resources. The compressed air from the compressor stages is directed through the purge holes into the groove to remove attachments, enabling the system to maintain its performance without requiring external cleaning systems
2Reliability
If the groove is formed to suppress stall on highly loaded rotor blades, then stall is suppressed during activation, but liquid membrane and impurities accumulate in the groove when droplets are not sprayed, reducing its effectiveness
Solution Approach 1:
The patent implements feedback control by using sensors to detect the presence and amount of liquid membrane and impurities in the groove. The detection device monitors the groove condition and provides feedback to the control device, which then adjusts the purge air supply accordingly - increasing purge intensity when attachments are detected and reducing it when the groove is clean, thereby maintaining stall suppression effectiveness while optimizing purge system operation
Solution Approach 2:
The purge system operates periodically rather than continuously, with the purge air supply device activating at regular intervals or based on operational conditions. This periodic purging removes accumulated attachments while minimizing the energy consumption and complexity associated with continuous purge operations
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The purge system effectively removes attachments from the casing grooves, stabilizing compressor activation and improving reliability by preventing stall occurrences and maintaining efficient operation across varying load conditions.
Implementation Method 1
a purge system for supplying high-pressure gas to the groove through the communication hole so as to remove a liquid membrane within the groove
Implementation Method 2
the droplets evaporate on an air intake side of the compressor thereby depriving the air of heat. Thus, the temperature of the suction air is reduced
Implementation Method 3
When droplets are sprayed in the suction air of the compressor, the droplets evaporate on an air intake side of the compressor thereby depriving the air of heat
Implementation Method 4
the droplets that collide with the rotor blades are blown to an outer side in a radius direction by centrifugal force caused by rotations of the rotor blades and reach the inner circumferential surface of the casing
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An axial compressor that can remove an attachment within a groove of a casing and recover an effect of suppressing stall on rotor blades, and a gas turbine provided with the axial compressor, are provided. The axial compressor includes a compressor body 6 and a sprayer 9 for spraying droplets in suction gas of the compressor body 6 so that the droplets are introduced into the compressor body 6 and evaporate. The compressor body 6 includes a casing 11, a rotor 12, rotor blades 13, and stator vanes 14. A groove 21 is formed in an inner circumferential surface of the casing 11 so as to be positioned around rotor blades 13 arranged on a front stage side. A purge system 23 is provided that supplies high-pressure air to the groove 21 through communication holes 22.