Variable Vane Scheduling for Compressor Stability
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Solution Overview
Problem
Existing turbomachine systems face challenges in optimizing variable vane scheduling, particularly in relation to bleed air conditions, which affect compressor stability and efficiency, especially in high-bypass ratio engines where bleed air reduces air flow to the turbine section, potentially shortening component life.
Innovation Solution
A method of variable vane scheduling that adjusts positions based on bleed air conditions, with distinct schedules for low and high bleed air scenarios, incorporating rotational speed and compressor inlet temperature to optimize airflow and maintain compressor stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If variable vane position is scheduled as a function of corrected engine parameters, then compressor stability is protected, but the system does not account for bleed air conditions affecting turbine section performance
Solution Approach 1:
The vane scheduling system transitions from a static schedule based only on corrected engine parameters to a dynamic schedule that adapts in real-time to bleed air conditions. The controller dynamically adjusts vane positions based on detected bleed air presence, allowing the system to respond to changing operational conditions and optimize both compressor stability and turbine section performance.
Solution Approach 2:
The system changes the scheduling parameter from solely corrected engine parameters to a combination of corrected engine parameters and bleed air detection signals. This parameter change enables the vane positioning to account for the reduced airflow conditions caused by bleed air extraction, thereby protecting compressor stability while adapting to turbine section requirements.
2Ease of operation
If bleed air is extracted from the compression section, then air cooling and other functions are supported, but airflow to the turbine section is reduced, potentially shortening component life
Solution Approach 1:
The controller implements feedback by detecting bleed air conditions and using this information to adjust variable vane positions. This closed-loop control ensures that when bleed air is extracted, the vane positions are optimized to compensate for the reduced airflow to the turbine section, thereby maintaining turbine component life while preserving the air cooling function.
3Device complexity
If a single variable vane schedule is used, then control is simplified, but optimization under varying bleed air conditions is compromised
Solution Approach 1:
The control system is segmented into multiple schedules, with at least a first schedule for when bleed air is present and a second schedule for when bleed air is absent or at different levels. This segmentation allows each schedule to be optimized for specific operational conditions, improving overall turbomachine efficiency while maintaining manageable control complexity through conditional selection.
Data Source
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AI summary
An example variable vane scheduling method includes adjusting variable vanes from a position based on a first schedule to a position based on a different, second schedule in response to a control feature. An example method of controlling flow through a compressor of a turbomachine includes moving variable vanes to positions that allow more flow into the compressor in response to bleed air being communicated away from the compressor.