Centrifugal Compressor Diffuser Fluid Injection for Stall Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Centrifugal compressors in gas turbine engines face instabilities such as rotating stall and surge, which are exacerbated by diffuser pipe designs, and conventional solutions require expensive hardware upgrades or modifications.
Innovation Solution
A diffuser assembly with a fluid injection assembly that injects compressible fluid into the diffuser pipes downstream of the aerodynamic throat to energize the boundary layer, preventing flow separation and improving aerodynamic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional passage control techniques (changing throat size or overboard bleed) are used to improve stall range, then compressor stability is improved, but hardware cost and complexity increase
Solution Approach 1:
The patent uses fluid injection (pneumatic principle) by introducing a secondary fluid stream into the diffuser passage to control flow separation and improve stall range. This hydraulic/pneumatic approach replaces mechanical modifications like throat size changes or overboard bleed systems, achieving compressor stability improvement without increased hardware complexity
Solution Approach 2:
The invention changes the flow parameters within the diffuser passage by injecting additional fluid, which modifies the boundary layer characteristics and pressure distribution. This parameter change approach improves stall range without requiring physical modifications to the diffuser geometry or additional hardware components
2Productivity
If diffuser pipe design is optimized to prevent flow separation, then aerodynamic performance is improved, but manufacturing complexity increases
Solution Approach 1:
Instead of modifying the diffuser pipe geometry to prevent flow separation (which would increase manufacturing complexity), the patent uses fluid injection to actively control the flow. This pneumatic approach maintains simple diffuser pipe manufacturing while achieving improved aerodynamic performance through flow control
Solution Approach 2:
The injected fluid acts as an intermediary that mediates between the main flow and the diffuser pipe wall, preventing flow separation without requiring changes to the pipe design. This intermediary approach maintains manufacturing simplicity while improving aerodynamic performance
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 fluid injection assembly enhances the stall range and reduces flow blockage, leading to improved compressor stability and efficiency without the need for costly hardware changes.
Implementation Method 1
a fluid injection assembly configured to supply a compressible fluid to the diffuser pipes and inject the compressible fluid into the diffuser pipes downstream of an aerodynamic throat of each of the diffuser pipes
Implementation Method 2
injects compressible fluid into the diffuser pipes downstream of the aerodynamic throat to energize the boundary layer, preventing flow separation
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A centrifugal compressor (14a) having at least a diffuser (20) is disclosed. The diffuser (20) has an annular diffuser body (30) having circumferentially spaced apart diffuser passages (32) defining fluid paths through the diffuser body (30). The diffuser also has a plurality of diffusion members (40) mounted to the annular diffuser body (30). Each diffusion member (40) has a member inlet (42) in fluid communication with a diffuser passage (32) and a member outlet (44). Each diffusion member (40) defines an aerodynamic throat disposed between the member inlet (42) and the member outlet (44). The diffuser (20) also has a fluid injection assembly (50) with multiple injection conduits (54). Each injection conduit (54) extends between a conduit inlet (56) configured to receive a flow of compressible fluid from a supply (52) and a conduit outlet (58) communicating with a corresponding diffusion member (40) downstream of the aerodynamic throat. The compressible fluid is injected through the conduit outlet (58) into the diffusion members (48).