Airfoil Boundary Layer Separation Control via Self-Service Jet Injection
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Solution Overview
Problem
Gas turbine airfoils, especially those highly loaded and operating at low Reynolds Numbers, are susceptible to fluid separation, which compromises aerodynamic performance, and existing vortex generator jet systems introduce efficiency losses and mechanical complexity.
Innovation Solution
An airfoil design featuring passages with discrete intake and discharge openings that extract fluid from the pressure surface and inject it as a jet onto the suction surface at specific angles to counteract fluid separation, minimizing aerodynamic losses and mechanical complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vortex generator jets are used to combat separation, then fluid separation resistance is improved, but engine efficiency deteriorates due to air extraction from the compressor
Solution Approach 1:
The airfoil uses its own pressure surface flow to drive the vortex generator jets through pressure differential, eliminating the need for external compressed air supply. The jet injection is self-sustaining using the airfoil's inherent pressure distribution
Solution Approach 2:
The invention extracts only the necessary jet injection function from the conventional VGJ system, removing the complex compressed air supply infrastructure while retaining the separation counteracting capability through direct pressure-driven injection
2Reliability
If vortex generator jets are used to combat separation, then fluid separation resistance is improved, but mechanical complexity increases due to the supply system
Solution Approach 1:
The invention extracts and eliminates the complex compressed air supply system, piping, and control mechanisms from conventional VGJ arrangements, retaining only the essential jet injection function achieved through pressure-driven flow through the airfoil structure
Solution Approach 2:
The airfoil structure itself provides the driving force for jet injection through pressure differential, eliminating the need for external compressors, control systems, and complex supply infrastructure
3Weight of moving object
If highly loaded airfoils are used to reduce airfoil count, then engine weight and complexity are reduced, but fluid separation susceptibility increases
Solution Approach 1:
The airfoil incorporates localized vortex generator jet features at specific positions on the suction surface where separation is most likely to occur, providing targeted separation control without requiring extensive modifications to the entire airfoil structure
Solution Approach 2:
The invention modifies the flow parameters by injecting high-velocity jets at specific locations and angles to alter the boundary layer characteristics and prevent separation, enabling highly loaded airfoils to operate without excessive separation
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 airfoil design effectively resists fluid separation while maintaining engine efficiency and reducing mechanical complexity by optimizing the injection of fluid jets to enhance momentum transport and prevent separation, thereby improving aerodynamic performance.
Implementation Method 1
The passage has an intake end with an intake opening that penetrates the pressure surface for extracting fluid from the working medium flow
Implementation Method 2
The discharge end has a discharge opening that penetrates the suction surface. The passage is configured to inject the jet at a jet angle whose components include a streamwise angle
Implementation Method 3
The vortices transport higher momentum free stream fluid into the lower momentum boundary layer, thereby counteracting any proclivity for fluid separation
Implementation Method 4
Each jet penetrates through the fluid boundary layer on the suction surface and interacts with the free stream portion of the working medium fluid to create a pair of counterrotating, streamwisely extending vortices in the free stream
Data Source
Figure 1~2
Figure 3
Figure 4~6
AI summary
An airfoil disclosed herein comprises a pressure surface (42) exposed to a stream of fluid (Fp), a suction surface (40) exposed to the stream of fluid (Fs) and a passage (56) extending from a passage intake end (60) to a passage discharge end (66). The intake end (60) has an intake opening (62) penetrating the pressure surface (42) for extracting fluid from the fluid stream (Fp). The discharge end (66) has a discharge opening (68) penetrating the suction surface (40) upstream of a natural separation point (52). The discharge end (66) is configured to inject the extracted fluid into the fluid stream at a jet angle whose components include at least one of a nonzero streamwise angle (α) in a prescribed angular range and a nonzero cross-stream angle (β).