Blade Cascade Stage Surface Contouring for Secondary Flow Reduction
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Solution Overview
Problem
Turbomachines experience significant secondary flows and vortex-induced pressure losses due to fluid interaction with side walls in the annular space, which existing contouring designs fail to adequately mitigate.
Innovation Solution
A blade/vane cascade segment with strategically designed elevations and depressions on the stage surface, where the first elevation extends to the pressure side of one blade/vane element and the second elevation to the suction side of an adjacent element, with carefully controlled axial and peripheral extensions to minimize secondary flow by influencing the static pressure field and reducing eddy formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If side wall contouring is introduced to reduce secondary flows, then pressure losses are reduced, but the complexity of the stage surface increases
Solution Approach 1:
The stage surface is segmented into multiple functional zones: a first contouring region with a first elevation on the pressure side, a second contouring region with a second elevation on the suction side, and intermediate strips between blade elements. Each segment performs a specific function in controlling secondary flows, allowing complex flow management through modular surface features rather than a single complex contour
Solution Approach 2:
Different regions of the stage surface are given different geometric properties tailored to local flow requirements. The first elevation has specific axial and peripheral extensions optimized for pressure side flow control, while the second elevation has dimensions optimized for suction side flow control. This local customization of surface quality enables effective secondary flow reduction without uniformly increasing complexity across the entire stage
2Loss of energy
If elevations and depressions are added to contour the side walls, then secondary flows are reduced, but manufacturing complexity increases
Solution Approach 1:
The first elevation, second elevation, and intermediate strips are merged into a single integrated stage surface structure. The boundary lines of these features are defined to meet at specific points, creating a continuous surface that can be manufactured as a single piece rather than assembling multiple separate components, thereby reducing manufacturing complexity despite the increased geometric complexity
Solution Approach 2:
The contouring features are designed with specific dimensional relationships in multiple dimensions: the axial extensions are limited to 10-20% of cascade span, peripheral extensions are limited to 10-20% of pitch distance, and the elevations reach specific heights (first elevation up to pressure side, second elevation up to suction side). These multi-dimensional constraints provide a systematic design framework that simplifies manufacturing by defining clear geometric boundaries
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
This design effectively reduces secondary flows and pressure losses, enhancing the flow efficiency through the blade/vane channel and improving the performance of downstream blade/vane cascades.
Implementation Method 1
with carefully controlled axial and peripheral extensions to minimize secondary flow by influencing the static pressure field and reducing eddy formation
Data Source
AI summary
A blade/vane cascade segment of a blade/vane cascade for a turbomachine is disclosed, which comprises a stage with a stage surface as well as a first blade/vane element and a second blade/vane element. The stage surface comprises a first elevation reaching as far as the pressure side of the first blade/vane element and a second elevation reaching as far as the suction side of the second blade/vane element. A furthest downstream point of a boundary of the second elevation has an axial position which differs from the axial position of at least one highest point of the first elevation by a maximum of 10% of an axial cascade span. Furthermore, a blade/vane cascade, a blade/vane channel, a stage, a turbomachine and an aircraft engine are disclosed.