Tandem Stator Vane Rows for Transonic Flow Deflection
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Solution Overview
Problem
Transonic compressors face challenges in maintaining efficient airflow straightening and deflection due to high aerodynamic loads and large variations in incidence angles, particularly in the last compression stage, which can lead to airflow separation and reduced efficiency.
Innovation Solution
A turbomachine stator assembly with a tandem configuration of two successive rows of stator blades, optimized through geometric parameters such as angular pitch, circumferential spacing, and blade angles, to achieve wide-range flow deflection and incidence tolerance, improving aerodynamic performance and resistance to load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the number of compression stages is reduced to reduce size and weight, then the turbomachine becomes more compact, but the rotor must rotate faster to achieve equivalent compression ratio
Solution Approach 1:
The stator is divided into two separate rows of blades (first row and second row) arranged in tandem. The first row handles flow deflection while the second row completes the straightening operation. This segmentation allows each row to be optimized independently for its specific function, enabling the compact design without requiring excessive rotor speed.
2Ease of operation
If blade camber is increased to achieve necessary flow deflection at high speeds, then flow straightening capability improves, but boundary layer separation occurs reducing compressor efficiency
Solution Approach 1:
The flow deflection function is segmented between two rows of blades. The first row with higher camber handles the initial flow deflection, while the second row with lower camber completes the straightening. This distribution prevents any single blade from requiring excessive camber that would cause boundary layer separation, thereby maintaining compressor efficiency.
Solution Approach 2:
Different camber values are assigned to different rows of blades based on their specific functions. The first row has higher camber for aggressive flow deflection, while the second row has lower camber for gentle completion of straightening. This local optimization ensures efficient flow control without causing boundary layer separation.
3Adaptability or versatility
If large angle of incidence variation is tolerated to accommodate wide operating range, then adaptability improves, but sonic blockages and separation risks increase
Solution Approach 1:
The incidence angle variation is segmented across two rows of blades. The first row is designed to tolerate larger angle variations for adaptability, while the second row operates with more constrained angles to avoid sonic blockages and separation. This segmentation allows the system to achieve wide operating range without the harmful effects associated with large single-stage incidence variations.
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
The tandem configuration enhances airflow straightening and deflection capabilities, reducing aerodynamic losses and improving surge margin while maintaining efficiency across the turbomachine's operating range, including transonic conditions.
Implementation Method 1
Transonic compressors are characterized by a significant load on the rotor and stator blades because they must accelerate and straighten an airflow over a shorter axial distance
Implementation Method 2
the camber of the blades must be significant, but too great a camber presents the risk of reaching boundary flow conditions, conditions in which the airflow separates from the blades under the effect of the adverse static pressure gradient
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a stator assembly (32) of a turbomachine, characterized in that it comprises: internal and external supports; two successive rows of stator blades (33, 35) defining a tandem configuration, comprising an annular row of upstream blades (33) extending substantially radially between the internal and external supports, and an annular row of downstream blades (35), located downstream of the upstream blades (33), extending substantially radially between the internal and external supports.