Variable Diffuser Penny Vane Mechanism for Compressor Stall Margin
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Solution Overview
Problem
Centrifugal compressors face reduced efficiency and stall margin when operating off their design point, necessitating improved diffuser area variation to enhance performance across varying operating conditions.
Innovation Solution
A variable diffuser system with rotatable pennies and vanes, allowing continuous adjustment of vane orientation and passage area between a hub and a tip, coupled with an actuator for precise control of fluid flow, improves stall margin and efficiency during low flow conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a centrifugal compressor is designed for maximum efficiency at the design point, then efficiency and minimum surge margin are optimized at that specific operating condition, but efficiency and stall margin are reduced when operating off the design point
Solution Approach 1:
The patent applies the dynamics principle by making the diffuser vanes movable rather than fixed. Each vane is coupled to a rotatable penny that can be independently positioned to change the diffuser passage area. This dynamic adjustment capability allows the compressor to adapt to different operating conditions, improving both stall margin and efficiency across a range of operating points, not just at the design point.
2Reliability
If the diffuser area is varied to improve efficiency and stall margin off the design point, then compressor performance is enhanced across varying operating conditions, but the device complexity increases due to multiple movable components
Solution Approach 1:
The patent applies segmentation by dividing the diffuser into multiple discrete vanes, each with its own penny mechanism. This allows independent control of each vane's position and orientation. The segmentation enables precise adjustment of the diffuser passage area while distributing the mechanical complexity across multiple simple, identical units rather than one complex mechanism.
Solution Approach 2:
The patent applies parameter changes by varying the angular position of each penny to control vane orientation and the diffuser passage area. By changing the rotational parameter of the pennies, the system adjusts the diffuser geometry to optimize performance for different operating conditions, achieving adaptability through simple rotational parameter adjustment.
3Measurement precision
If multiple pennies are used to control vane positioning, then angular control and accuracy of vane orientation is improved, but the manufacturing complexity and assembly difficulty increase
Solution Approach 1:
The patent applies homogeneity by using identical penny mechanisms for each vane. Each penny has the same structure, coupling method, and actuation mechanism. This standardization simplifies manufacturing and assembly, as the same components and procedures are repeated for each vane-penny assembly, reducing overall complexity despite the multiple components.
Data Source
Figure 1~2A
Figure 2B~3
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AI summary
A variable diffuser (200) comprises a passage (116), at least two vanes (118, 201) disposed within the passage, and at least two pennies (203). The passage is defined between opposing disk faces of a hub (121) and a tip (123). Each of the vanes comprises a vane body (209) having a leading edge (210) and a trailing edge (212). The body extends between the hub face and the disk face. Each of the pennies is coupled to a respective vane body near an edge of the penny and an actuator. Rotation of at least one penny changes the orientation of the respective vane relative to the hub face (120).