Air Gap Airfoils for Turbine Compressor Surge Margin
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Solution Overview
Problem
The parasitic air recirculation in turbomachines' compressors affects performance and operability, particularly during transient phases, due to uncontrolled flow direction and inertia, leading to air separation and reduced surge margin.
Innovation Solution
The addition of fins with specific profiles and orientations in the annular space between the moving and stator blades to guide and control the recirculated air, ensuring optimal orientation and reducing aerodynamic losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If air is reinjected upstream of the stator blades to maintain compression, then the compressor can operate, but the parasitic airflow causes air separation and reduces surge margin
Solution Approach 1:
A guide vane assembly is introduced as an intermediary component between the air reinjection source and the stator blades. This mediator redirects and conditions the parasitic airflow, transforming it from a harmful uncontrolled flow into a useful controlled flow that supports compressor operation without causing air separation.
Solution Approach 2:
The guide vanes modify the airflow parameters (direction, velocity distribution, angle of attack) by adjusting the geometric parameters of the flow path. This changes the flow characteristics from parasitic and separating to controlled and attached, improving surge margin while maintaining productivity.
2Loss of energy
If fins are added to guide the recirculated air, then airflow guidance is improved and aerodynamic losses are reduced, but device complexity increases
Solution Approach 1:
The guide vane assembly is segmented into multiple individual guide vanes arranged around the airflow path. Each vane handles a portion of the flow, allowing for optimized local flow control. This segmentation achieves effective airflow guidance and loss reduction while keeping each individual component simple and manageable.
Solution Approach 2:
The guide vanes extend in the radial dimension, creating a three-dimensional flow control structure. By utilizing the radial space between the air reinjection source and stator blades, the vanes effectively guide the flow without adding axial or circumferential complexity to the existing compressor architecture.
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
Improves the surge margin and efficiency by minimizing air separation at the stator blades, enhancing airflow guidance, and reducing aerodynamic losses during both stable and transient operations.
Implementation Method 1
The addition of fins with specific profiles and orientations in the annular space between the moving and stator blades to guide and control the recirculated air, ensuring optimal orientation and reducing aerodynamic losses
Data Source
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AI summary
The invention relates to a blade stage (16) with longitudinal axis X intended to be mounted in a turbomachine compressor (10) comprising an annular row of moving blades (12) arranged upstream of an annular row of stator blades (14), the annular row of stator blades (14) having an internal radially annular platform (20) which carries radial blades (18) and of which an upstream annular portion (20c) is arranged upstream of said blades (18) and surrounded radially outwards by a downstream annular portion (26d) of an annular platform (26) of the upstream annular row of moving blades (12), the upstream annular portion (20a) of the annular platform (20) of the annular row of stator blades (14) comprising an external annular face from which extend vanes (50) distributed around the longitudinal axis X and extending radially outwards towards the downstream annular part (26d) of the platform (26) of the annular row of moving blades (12).