Turbomachine Compressor Rotating Stall Suppression
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Solution Overview
Problem
Rotating stall in turbomachine compressors is a persistent aerodynamic instability that leads to partial blade stall, performance loss, and increased turbine temperatures, often resulting in engine overheating and potential destruction, with existing methods like shutting down and restarting the engine being inefficient and prone to failure, especially when caused by pumping.
Innovation Solution
A method that differentiates between rotating stalls caused by pumping and those not, involving a step to restore the surge margin by adjusting fuel flow and compressor settings, specifically reducing the 'CsurP' coefficient and modifying stator pitch angles to prevent reoccurrence, while implementing micro-cuts and fuel valve control to eliminate the stall.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the turbomachine is shut down and restarted to eliminate rotating stall, then the rotating stall is eliminated in most cases, but the engine restart failure rate is significant
Solution Approach 1:
The patent applies preliminary action by detecting rotating stall conditions before they fully develop and by preemptively adjusting operational parameters. The system monitors compressor operating points and predicts approaching stall conditions, allowing intervention before the stall becomes established, thereby preventing the need for shutdown-restart cycles and improving restart reliability.
Solution Approach 2:
The patent implements feedback control by continuously monitoring compressor performance parameters and using this information to adjust fuel flow and guide vane angles in real-time. This closed-loop control system detects deviations from stable operating regions and automatically corrects them, preventing rotating stall development and enabling more reliable restart operations.
2Device complexity
If a uniform suppression method is applied to all rotating stall types, then the control system is simple, but the re-ignition of the turbomachine fails systematically when rotating stall occurs after pumping
Solution Approach 1:
The patent applies segmentation by dividing rotating stall into distinct categories based on their causes and characteristics. The system identifies whether stall occurs during normal operation or after pumping events, and whether it affects the low-pressure or high-pressure compressor. This segmentation enables tailored suppression strategies for each stall type, improving re-ignition success rates without requiring overly complex control systems.
Solution Approach 2:
The patent implements dynamics by making the control system adaptive and responsive to different operating conditions. The suppression method dynamically adjusts parameters such as fuel flow rate and guide vane angles based on the detected stall type and current engine state. This dynamic approach allows the same control system to effectively handle multiple stall scenarios that would require different fixed strategies.
3Reliability
If the surge margin is restored by reducing the CsurP coefficient and modifying stator pitch angles, then surge and stall reoccurrence is prevented, but additional control mechanisms are required
Solution Approach 1:
The patent applies universality by using existing control components to perform multiple functions. The fuel injection system, originally designed for combustion control, is also used to manage surge margin by adjusting fuel flow. The variable geometry components, designed for performance optimization, are utilized for stall prevention by modifying stator pitch angles. This multi-functionality reduces the need for dedicated surge control mechanisms.
Solution Approach 2:
The patent implements parameter changes by systematically adjusting key operating parameters to restore and maintain surge margin. The CsurP coefficient is reduced to decrease compressor loading, and stator pitch angles are modified to optimize flow characteristics. These parameter changes are achieved through the existing control systems, avoiding the need for additional hardware while effectively preventing surge and stall reoccurrence.
Data Source
Figure 1~3
AI summary
The invention relates to a method for eliminating rotating stall in the compressor of a turbomachine, characterized in that said method comprises the following steps: - a step (103) of automatically detecting a surge in the turbomachine; - a step (104) of automatically shutting off the turbomachine; - if a surge has been detected, a step (106) of automatically restoring a surge margin; - a step (105) of automatically restarting the turbomachine.