Turbomachine Blade Stacking Line Curvature Inversion
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Solution Overview
Problem
The presence of clearance vortices between the intrados and extrados of compressor and turbine blades in turbomachines leads to efficiency losses, as existing solutions either incur additional production costs or fail to effectively control the vortex without modifying the compressor casing.
Innovation Solution
Modifying the shape of the blade by introducing a double axial inversion of the curvature over the last thirty percent of the blade's height, with inversions preferably located on the last ten percent, to better guide the airflow and reduce leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If treatments are applied to the casing or trenches are created to control the vortex, then the vortex control is improved, but the production cost increases and efficiency performance degrades at certain operating points
Solution Approach 1:
The invention applies a specific curvature modification (double axial inversion) only to the stacking line of the blade, creating a localized geometric feature that controls the vortex. This avoids the need for complex casing treatments or trenches, reducing manufacturing cost while maintaining vortex control effectiveness across different operating points.
Solution Approach 2:
The invention uses a double axial inversion of the curvature in the stacking line, which is a geometric inversion approach. By inverting the curvature direction in specific zones of the blade height, the airflow pattern is reversed or redirected to reduce vortex formation, providing an alternative to conventional casing-based solutions.
2Object-generated harmful factors
If the leading edge sweep angle is modified to reduce vortex impact, then the vortex control is improved, but the blade shape complexity increases without clear guidance on stacking line evolution
Solution Approach 1:
Instead of modifying the leading edge sweep angle in the planar view, the invention introduces a modification in the stacking line dimension (axial curvature). This adds a third-dimensional geometric feature to the blade, allowing vortex control through axial curvature variation rather than planar sweep angle modification, thus providing clearer manufacturing guidance.
Solution Approach 2:
The invention changes the geometric parameters of the blade by defining a specific stacking line evolution with double axial inversions. This parameter modification approach provides clear quantitative guidance for blade manufacturing, specifying exactly how the stacking line should evolve along the blade height to achieve vortex control.
3Strength
If undulations are added to the blade to increase bending rigidity, then the blade strength is improved, but the vibratory resistance problem is not addressed and it does not contribute to vortex control
Solution Approach 1:
The double axial inversion in the stacking line serves multiple functions simultaneously: it controls the clearance vortex to improve efficiency and provides structural reinforcement to increase bending rigidity. This multi-functional geometric feature eliminates the need for separate modifications for vortex control and structural strengthening.
Data Source
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AI summary
A turbine engine blade, including an airfoil which extends radially between a blade root and an airfoil tip, axially between a leading edge and a trailing edge, and tangentially between a pressure side and a suction side, the profile of the blade having a series of basic profiles, in a form of a vane section, stacked on one another along a stacking line connecting the center of gravity of all the vane sections. The projection of the stacking line of the airfoil on at least one plane extending radially from the blade root includes a double tangential inversion of the direction of the curvature thereof, located in the last thirty percent of the height of the airfoil, the projection plane being positioned substantially perpendicular to the chord of the blade.