Overlapping Tandem Stator Channel for Transonic Flow Control
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Solution Overview
Problem
Transonic compressors face efficiency losses due to flow separation and blockage phenomena when the overlap between blades exceeds 5% of the blade chord length, particularly in the last rectifier stage, which is critical for maintaining axial flow and compressor efficiency.
Innovation Solution
A stator design with an upstream and downstream blade configuration that axially overlaps, creating a channel with a larger inlet area than outlet area, defined by specific geometric surfaces and angles, to manage flow distribution and reduce blockage risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the overlap between blades is increased to reduce compressor size, then compactness is improved, but flow blockage phenomena and aerodynamic losses occur
Solution Approach 1:
The invention applies different geometric configurations to different parts of the blade system. Specifically, the upstream blade has a first configuration and the downstream blade has a second configuration, with different camber lines and curvature distributions. This local differentiation allows the channel between blades to maintain adequate flow passage area even with increased overlap, preventing blockage while achieving compactness.
Solution Approach 2:
The invention changes geometric parameters of the blade profiles, particularly the camber line curvature and blade thickness distribution. By optimizing these parameters, the channel cross-sectional area is maintained sufficient to prevent flow blockage while allowing greater axial overlap between blades, thus reducing overall compressor size without incurring aerodynamic penalties.
2Ease of operation
If the camber of the blades is increased to straighten the flow, then flow straightening is improved, but flow separation occurs
Solution Approach 1:
The invention employs different camber line configurations for upstream and downstream blades. The upstream blade has a camber line with specific curvature characteristics, while the downstream blade has a different camber line profile. This local differentiation allows effective flow straightening while controlling adverse pressure gradients to prevent boundary layer separation.
Solution Approach 2:
The invention utilizes optimized curved camber lines with specific radius of curvature variations along the blade span. The camber lines are designed with appropriate curvature distributions that promote smooth flow turning without creating excessive adverse pressure gradients, thereby preventing flow separation while achieving the required flow straightening effect.
Data Source
AI summary
A stator assembly including an upstream blade and a downstream blade axially overlapping and defining between them a channel. The inlet surface of the channel is greater than or equal to the outlet surface of the channel, preferably with a factor of 2. A turbomachine provided with such an assembly, arranged upstream of a high-pressure compressor.